AUTHOR AND EDITOR INFORMATION

Section 1 of 13  

• Authors and Editors
• Introduction and History
• Prerequisites for Vacuum Extraction
• Indications for Vacuum Extraction
• Contraindications to Vacuum Extraction
• Design of the Vacuum Extractor
• Vacuum Extraction Technique
• Birth Injuries
• Vacuum Extraction versus Forceps
• Conclusion
• Acknowledgments
• Multimedia
• References

INTRODUCTION AND HISTORY

Section 2 of 13  

• Authors and Editors
• Introduction and History
• Prerequisites for Vacuum Extraction
• Indications for Vacuum Extraction
• Contraindications to Vacuum Extraction
• Design of the Vacuum Extractor
• Vacuum Extraction Technique
• Birth Injuries
• Vacuum Extraction versus Forceps
• Conclusion
• Acknowledgments
• Multimedia
• References

Modern obstetric vacuum extraction (VE) originated in cupping, a therapeutic technique that predates Hippocrates.^{41, 58} In cupping, a metal or glass cup was heated over an open flame and placed over a lesion or skin puncture. As the cup cooled, a vacuum developed, extracting blood or other fluids. Cupping was also successfully used for certain surgical procedures, such as raising depressed skull fractures.

Applications of cupping to assist in deliveries began early in the 18th century. However, the use of vacuum for obstetric use proved difficult and the technique was soon abandoned. Several problems existed. A successful extraction required the vaginal application of a cup to the fetal head (and occasionally in premodern times, the buttocks), a means to apply traction, and the ability to periodically reinforce the vacuum. Before vacuum deliveries became practical, new cup design with improved methods for applying traction to the vacuum cup, and a more effective method to generate additional vacuum on demand were required.

It remained to James Young Simpson, an Edinburgh professor of obstetrics already famous for his forceps design, to first introduce a successful obstetric vacuum extractor in 1849. This device (his "air tractor") was constructed of a metal syringe that had probably been derived from a breast pump attached to a soft rubber cup. This extractor did prove successful in a number of deliveries but technical problems existed. Vacuum replenishment was impossible after the initial evacuation of the syringe and the device lacked a pelvic curve. These difficulties limited its effectiveness. Simpson's interest in his extractor waned and he moved on to other obstetric interests. Thereafter, the technique of obstetric VE promptly fell from clinical interest. In the century that followed, a number of vacuum delivery devices were invented and some were successfully tested by various clinicians. However, interest in obstetric VE was not revived and none of these devices achieved popularity.

The immediate antecedent to modern extractors is the stainless steel cup vacuum device introduced by Malmström in 1956. Because of technical problems with the original design and lack of experience with vacuum technique, case reports of severe fetal complications soon appeared in the American literature. Thus, interest in the Malmström cup was short lived. While VE remained common in Europe, the technique did not regain popularity in the United States until the early 1980s. This followed the introduction of disposable soft-cup extractors and later new rigid cup designs. These innovations, combined with improved technique, resulted in increased safety and a greater likelihood of successful operations.

Presently, both forceps and the vacuum extractor are in use as delivery instruments. Over the recent decade, VE has progressively replaced forceps as the delivery instrument of choice for many practitioners.^{29, 27} Controversy continues concerning if, and when, operative vaginal deliveries should be conducted and which instrument is the best to use in specific clinical settings.  

Despite the growing popularity of VE, forceps remain popular for many older clinicians for reasons of medical conservatism, inclination, and original training. Further, especially in the more complex fetal presentations, forceps deliveries are more likely to be successful than VE operations. Nonetheless, VE remains popular because of its reputation for ease of use, lower maternal morbidity, and supposed safety. Severe neonatal complications can, however, occur with vacuum operations. While uncommon, these problems remind practitioners of the need for rigorous adherence to proven techniques, proper education, and the need to restrict vacuum operations to well-defined indications to ensure success and avoid injury.^{13, 12, 41}

The retirement of classically trained obstetricians, the inability to conduct training operations, the medical-legal climate, and other changes in practice, including the high incidence of cesarean deliveries, now collectively contribute to an unclear future for all types of instrumental delivery, including vacuum extraction. Yet, a need still remains for delivery assistance that can be safely and expeditiously provided by an instrumental delivery with either the forceps or VE while avoiding the risk and expense of a cesarean operation.^{12, 37}  
 
This chapter reviews the physics of vacuum delivery instruments and the indications and contraindications for their use. Also, the limitations of VE in clinical obstetrics are considered, as is the choice of delivery technique (VE vs forceps vs cesarean delivery) when labor ceases or other complications ensue.

The vacuum extractor is an effective and safe device for assisted vaginal delivery and an important addition to the modern obstetrical armamentarium. The clinician must treat this instrument with respect to maximize the possibilities of its success while limiting the risks of maternal or fetal injury.

For related information, see Medscape's Pregnancy Resource Center.

PREREQUISITES FOR VACUUM EXTRACTION

Section 3 of 13  

• Authors and Editors
• Introduction and History
• Prerequisites for Vacuum Extraction
• Indications for Vacuum Extraction
• Contraindications to Vacuum Extraction
• Design of the Vacuum Extractor
• Vacuum Extraction Technique
• Birth Injuries
• Vacuum Extraction versus Forceps
• Conclusion
• Acknowledgments
• Multimedia
• References

The indications for vacuum extraction (VE) operations are the same as assisted delivery operations performed with forceps. The prerequisites for all types of instrumental delivery are discussed below.

Informed consent

Informed consent is required for any surgical procedure, including an instrumental delivery. Informed consent is best considered as a process and not simply a signed form. Consent for a surgical procedure requires an explanation of the need for the operation, a discussion of risks and benefits, and a presentation of alternative modes of treatment. The patient must also be given the opportunity to ask questions. This consent process may strike the clinician as time consuming and unrealistic for an instrumental delivery, especially in the face of urgency. However, the potential for maternal or fetal injury and thus the medical and legal risks from an assisted delivery are substantially greater than those associated with many other surgical procedures wherein consent is routinely obtained.

A bedside consent process can be abbreviated, especially in cases of presumed fetal jeopardy (nonreassuring fetal monitoring). In all cases, excluding extreme emergencies, sufficient time is available to briefly describe the proposed operation to the mother, review the indications, and state the limits of effort intended.

Routinely discussing possible obstetric interventions with families at an earlier time during the pregnancy is important because of the controversy concerning bedside consents in acute situations. When antepartum discussions have occurred and the need for an instrumental delivery procedure is later presented during labor, both the patient and family will already have a general idea about the procedure and its potential risks and benefits.

Prepared physician

The clinician must have knowledge of the instrument chosen, VE indications, and proven techniques. The decision to perform instrumentation should follow an analysis of the course in labor, a pelvic examination, and determination of fetal position and station and consideration of the fetal/pelvic relationship. Most importantly, the accoucheur must be prepared to reconsider or abandon any operation that proves difficult.

Prepared patient

The initial requirement is consent. Thereafter and prior to an extraction attempt, the patient should have ruptured membranes; empty bladder by Credé, catheterization, or spontaneous voiding; full cervix dilation; an engaged fetal head; and no suspicion of fetopelvic disproportion. If the fetal position or the station of the presenting part is uncertain, a transperineal or transvaginal real time ultrasonographic examination can be performed before attempting the operation.¹ Ultrasonography can also be used to judge the appropriateness of the vacuum cup application.^{23, 57} These procedures are easily performed at the bedside. Position is readily identified by noting the fetal orbits and identifying characteristic intracranial anatomy (falx, posterior fossa, etc). Station can be estimated by translabial scanning and requires more experience.

Acceptable analgesia/anesthesia

Some outlet operative VE deliveries can be conducted without anesthesia or analgesia. However, parturients do find operative vaginal procedures painful. Usually, either a regional anesthetic (eg, pudendal block) or, more frequently (and more effectively), a conduction anesthetic (eg, epidural, spinal, saddle block) is required.

INDICATIONS FOR VACUUM EXTRACTION

Section 4 of 13  

• Authors and Editors
• Introduction and History
• Prerequisites for Vacuum Extraction
• Indications for Vacuum Extraction
• Contraindications to Vacuum Extraction
• Design of the Vacuum Extractor
• Vacuum Extraction Technique
• Birth Injuries
• Vacuum Extraction versus Forceps
• Conclusion
• Acknowledgments
• Multimedia
• References

Prolonged second stage of labor

An extended second stage of labor is a relative, but not absolute, indication for an instrumental delivery. Clinical reports prior to the 1970s suggested that fetal morbidity and mortality were higher with a prolonged second stage of labor. However, Cohen¹⁵ and Menticoglou³⁴ found a poor relationship between the length of the second stage of labor and infant mortality or morbidity, assuming proper maternal/fetal monitoring.

Classically, parity and the presence or absence of epidural anesthesia determined whether the second stage is prolonged. In general, second stages of more than 2 hours without epidural anesthesia and 3 hours with were the acceptable measures for nulliparas. One hour less in each category was the limit for multiparas. These times are not considered as absolute markers to determine the need for prompt intervention but more as indicators to identify a point to stop, consider if progress is continuing, and evaluate maternal and fetal condition. Thus, while intervention may or may not occur at the classical second stage intervals, in all cases evaluation must be performed.⁴¹

Yet, clinicians must not ignore tardy progress. Fetal malpositioning, including cranial deflection, an occiput posterior or another uncommon presentation, or true fetopelvic disproportion could be the cause. In modern practice, both pelvic deformity and absolute disproportion are uncommon. Thus, not surprisingly, when trials of vaginal birth after cesarean delivery (VBAC) are attempted, success rates are in the range of 60-70% even when the indication for the initial surgery was failure to progress.⁵ This indicates that most dystocia is due to complex combinations of poor or incoordinate uterine activity combined with subtle degrees of deflection or other mild malpresentations rather than true anatomic disproportion. 

The second stage can be safely extended the mother can tolerate a longer labor, serial examinations document continued progress, the fetal condition is reassuring, and the fetal positioning permits a vaginal trial.

Shortening of the second stage of labor

On occasion, shortening of the second stage of labor is the best management. In some maternal disorders (eg, cardiac, cerebrovascular, neuromuscular), voluntary expulsive efforts are contraindicated or impossible. Additional situations that might lead to intervention include maternal exhaustion following a long labor or, possibly, overly dense epidural analgesia. These latter indications should not be overused. Thus, these indications are best considered relative. Maternal exhaustion is a subjective determination and can be modified with rest, rehydration, positional changes, and encouragement. Likewise, the intensity of analgesia/anesthesia can be altered, if necessary.

Presumed fetal jeopardy/fetal distress

The suspicion of a seriously stressed or potentially jeopardized infant is a classic indication for operative delivery. This is exactly the setting in which extra caution is indicated. Proper case choice is not easy because current methods of fetal surveillance by electronic fetal monitoring are imprecise and the accurate diagnosis of fetal jeopardy can still elude us, except in extreme instances.

When prompt delivery is believed to be indicated, station and position of the fetal head, the fetopelvic relationship, operator skill, and a judgment of the degree of jeopardy dictate the mode of delivery. For most practitioners, cord prolapse, abruptio placentae, or persistent bradycardia at a high station, even at full dilation with an engaged head are best managed by cesarean delivery.

Nonetheless, expedited vaginal delivery using vacuum extraction or forceps is appropriate in selected cases. Such instances usually involve a rapidly progressing labor when the maternal pelvis is adequate, the infant is normally presenting, the parturient is willing and able to assist, and an experienced obstetrician is present. However, bitter experience reminds us that any delivery cannot be guaranteed to occur vaginally, except in retrospect. Thus, emergency applications of either the forceps or a vacuum extractor are often best conducted as trials, as described below.

Trials of instrumental delivery

Clinical medicine is not an exact science. Thus, success in an attempted instrumental vaginal delivery cannot always be accurately predicted.  Even the best clinicians occasionally encounter difficulty in estimating the probability of success in any attempt at a vaginal delivery. The important issues to note are how cases are initially evaluated, the approach taken to both recognized trials, and the approach in situations in which success is anticipated but does not occur. Moving to a cesarean delivery if an extraction is not performed easily does not indicate a clinical failure but is simply a reflection of the limitations of clinical prediction. Heroic vaginal operations have no place in modern obstetric management. The cardinal admonition during all instrument deliveries, whether identified as trials or not, is not to doggedly persist in the face of failure or poor progress.
  
A trial of instrumental delivery is an obstetric operation in which delivery is indicated and the vaginal route is considered to be possible, but the outcome is uncertain. While all instrumental delivery efforts include an element of uncertainty, a trial procedure is specifically characterized by simultaneous preparations for a cesarean if the vaginal procedure does not proceed rapidly and easily. Trials are infrequent. 

A trial of instrumental delivery differs from a failed procedure. The latter occurs in a setting in which the instrumental delivery is anticipated to be successful and no preparations for an alternative approach are made. In these cases, the greatest discipline is necessary to avoid attempting to overcome relative or perhaps true disproportion by multiple efforts or increasing force.
 
The following steps are suggested in instrumental delivery trials:

• The most experienced clinician remains at the perineum, while maternal bearing down efforts are actively recruited (as appropriate, in light of EFM or ausculatory data).
• Other personnel simultaneously prepare for a cesarean delivery.
• An instrument is applied.
• Traction is applied during contractions and while maternal bearing down efforts are encouraged.
• If the operation does not proceed easily and promptly with rapid descent of the presenting part, the attempt is abandoned and a cesarean delivery is performed.

Trials are often best conducted in an operating room, but clinical realities may dictate the use of other sites. These operations demand the highest degree of attention and judgment from the surgeon. 

CONTRAINDICATIONS TO VACUUM EXTRACTION

Section 5 of 13  

• Authors and Editors
• Introduction and History
• Prerequisites for Vacuum Extraction
• Indications for Vacuum Extraction
• Contraindications to Vacuum Extraction
• Design of the Vacuum Extractor
• Vacuum Extraction Technique
• Birth Injuries
• Vacuum Extraction versus Forceps
• Conclusion
• Acknowledgments
• Multimedia
• References

Vacuum operation is contraindicated in the following instances:

• Operator inexperience
• Inability to achieve a correct application
• An inadequate trial of labor
• Lack of a standard indication
• Uncertainty concerning fetal position and station
• Suspicion of fetopelvic disproportion
• Fetal malpositioning (eg, breech, face, brow)
• Known or suspected fetal coagulation defects

• Prematurity (fetus <36 wk gestation): Vacuum extraction (VE) applications are not recommended at less than 36 weeks' gestation. Data are limited and the magnitude of risk is not known with certainty. The physics of scalp entrapment by the cup mechanism and the known fragility of intracranial vascular structures in the premature infant mitigate against such applications unless special circumstances exist. This issue is reviewed in greater detail below.
• Prior scalp sampling: Scalp sampling is now an uncommon procedure. A prior sampling is not normally a problem in a VE operation. In very unusual circumstances, fetal bleeding has occurred with VE in this setting but the risk is remote, at best. Prior application of a scalp electrode does not preclude VE use.
• Prior failed forceps: Prior failed forceps is usually a contraindication to any VE effort. Serial instrumentation is discussed in more detail below. As a practical matter, the forceps can generate more traction force than the VE. Thus, to follow a forceps effort with a VE trial is not inherently reasonable unless circumstances have prevented the successful application of a forceps before traction has been attempted. An example might be the inability to achieve (or properly verify) an appropriate forceps application after blade insertion. Such cases must be quite unusual and should prompt immediate caution as heavy cranial molding and advanced caput (both harbingers of disproportion) are likely to be present.
• Overlapping cranial bones, heavy caput: Overlap of cranial bones, the inability to palpate the standard landmarks, and cranial edema (caput/cephalohematoma) are suggestive of at least relative disproportion. When these findings are combined with poor progress, the clinician may find that the presenting part is substantially higher than initially anticipated. True disproportion may be present, precluding any vaginal trial. As previously noted, the bedside evaluation of such cases when real time ultrasonographic scanning can be of particular assistance.¹
• Known or suspected fetal macrosomia: A large infant (estimated fetal weight >4,500 g in a nondiabetic) can only be considered as a relative contraindication to instrumental delivery. This is primarily because our methods of estimation of fetal bulk are so limited and inaccurate. While ultrasonographic scanning is often used for weight estimates at or near term, in most cases, such estimates are considered as +/- 6-12%, with only 40-75% of these estimates falling within this range. These ultrasonographic data should not be used as the sole means for the estimation of fetal bulk or for making obstetric management decisions. This information is only useful to the clinician when combined with other information that dynamically evaluates the fetopelvic relationship (eg, Muller-Hillis maneuver, overlap of cranial bones, course in labor, pelvimetry).

Definitions

The American College of Obstetricians and Gynecologists (ACOG) has established standard definitions for instrumental delivery operations. These include outlet, low, and midpelvic operations. Coding depends on the clinical assessment of fetal position and station immediately prior to initiating an operation. While the guidelines were originally written for forceps procedures, the same descriptions are easily applied to vacuum extraction operations with minor modifications.³

Table 1. Proposed Classification for Vacuum Extraction Procedures According to Fetal Station and Cranial Position (modified from ACOG Practice Bulletin # 17, June, 2000)

Type of Procedure	Description of Classification*
Outlet-vacuum operation	The fetal head is at or on the perineum; the scalp is visible at the introitus without separating the labia; the fetal skull has reached the pelvic floor. The sagittal suture is in the AP diameter (ROA, LOA, OA) or posterior (ROP, LOP, OP) position.
Low-vacuum operation	The position/station of the fetal head does not fulfill the criterion for an outlet operation; the leading edge of the fetal skull is at station +2/5 cm, but has not reached the pelvic floor.†
Subdivisions	(a) Position is occiput anterior (OA, LOA, ROA). (b) Position is occiput posterior (OP, LOP, ROP) or transverse (LOT, ROT).
Midvacuum operation	Station <+2/5 cm; the fetal head is engaged but the criterion for outlet or low operations are not fulfilled.
Subdivisions	(a) Position is occiput anterior (OA, LOA, ROA). (b) Position is occiput posterior (OP, LOP, ROP) or transverse (LOT, ROT).
Vacuum-assisted cesarean delivery	This includes all vacuum-assisted cesarean deliveries, unspecified technique.
Special vacuum operations	This includes vacuum extraction operations not otherwise specified; full details are described in the dictated operative note.
High-vacuum operation	Such procedures are not included in the classification.

OA: occipitoanterior; ROA: right occipitoanterior; LOA: left occipitoanterior; OP: occipitoposterior; LOP: left occipitoposterior; ROP: right occipitoposterior; LOT: left occipitotransverse; ROT: right occipitotransverse

*The type of operation coded in the medical record is determined by pelvic examination noting the position and station of the fetal head at the time the extraction is initiated.

†To standardize nomenclature, especially as other methods were used in the past, the authors recommend the ACOG ±5 cm system for the reporting of station, with certain modifications. Station (recorded as +5 to –5 cm) is defined as the distance in centimeters from the leading bony portion of the fetal skull to the imaginary plane of the maternal ischial spines. In the authors' practice, they determine station by first conducting a pelvic examination, noting the distance from the presenting part to the ischial spines. This number is then entered into the medical record, followed by a notation specifying the technique used for reporting. Thus, if the clinician's estimate is that the bony presenting part is 2 cm below the plane of the ischial spines, a station of +2/5 cm is recorded.

Note that formal dictation of all vacuum operations is recommended, regardless of the apparent ease of the procedure or the initial condition of the neonate.

DESIGN OF THE VACUUM EXTRACTOR

Section 6 of 13  

• Authors and Editors
• Introduction and History
• Prerequisites for Vacuum Extraction
• Indications for Vacuum Extraction
• Contraindications to Vacuum Extraction
• Design of the Vacuum Extractor
• Vacuum Extraction Technique
• Birth Injuries
• Vacuum Extraction versus Forceps
• Conclusion
• Acknowledgments
• Multimedia
• References

Vacuum extraction instruments

New models of VE instruments represent modifications of current devices, usually by the addition of incorporated hand pumps, pressure release valves or gauges, and other changes. Modern extractors are constructed of varying materials including polyethylene or silastic plastic and stainless steel. Several features are found in all VE designs. These include the following:

• A mushroom-shaped vacuum cup of varying composition and depth
• A cup including a fixed internal vacuum grid or guard
• A combined vacuum pump/handle or a vacuum port to permit a vacuum hose attachment
• A handle, wire, or chain for traction

Rigid-cup designs include the classic Malmström stainless steel vacuum cup and the various modifications of this instrument introduced since the 1960s. Now rigid plastic cup extractors mimic the Malmström device. These were originally designed for use with deflexed or posterior positioned heads but now are becoming popular for all types of deliveries.²²

The soft-cup extractors include a number of disposable polyethylene or combined polyethylene-silastic cup designs that differ in largely inconsequential ways. Limited data permit comparison of these devices in terms of relative risk or clinical efficacy. The differences observed in cup design between manufacturers reflect marketing decisions rather than scientifically proven extraction efficacy or improved safety.

Comparison of instruments

Soft or flexible vacuum cups have a higher incidence of failure than either rigid vacuum cups (plastic or metal) or forceps.²⁵ This is primarily due to their higher frequency of spontaneous detachment pop-offs. However, the application of soft vacuum cups also results in less fetal cosmetic injury (principally scalp injury) than rigid cups. This partially reflects the inability of soft cups to generate the same degree of scalp traction as is possible when rigid cups are applied.

Other design issues are important to cup choice. In most plastic extractor designs, the relatively rigid tube connecting the handle to the cup precludes accurate placement of the instrument when the fetal head is markedly deflexed or occiput posterior. This contributes to failure in the relatively small number of cases when such cranial malpositions are present. Higher success rates have recently been reported when rigid plastic cups similar to the original Malmström design are used for such deflexed and posterior presentations.

VACUUM EXTRACTION TECHNIQUE

Section 7 of 13  

• Authors and Editors
• Introduction and History
• Prerequisites for Vacuum Extraction
• Indications for Vacuum Extraction
• Contraindications to Vacuum Extraction
• Design of the Vacuum Extractor
• Vacuum Extraction Technique
• Birth Injuries
• Vacuum Extraction versus Forceps
• Conclusion
• Acknowledgments
• Multimedia
• References

Proper technique is vitally important to the safety and success of vacuum extraction (VE) operations.^{50, 35, 41, 58} A proper vacuum-conducted extraction operation depends on the following:

• The accuracy of the initial cup application (ie, cup center over pivot-point)
• Case choice
• The traction technique
• • Degree of effort 
  • Vector of traction 
  • Method of applied force
• The fetal cranial position (including deflection) and fetal station at the time of application
• The cup design
• The fetopelvic relationship

Application

After the prerequisites for VE operation are met and consent is obtained, the position, station, and attitude of the fetal head are verified by pelvic examination and an instrument is chosen. Thereafter, a specific protocol is followed.^{50, 41}

• Ghosting: A ghost or phantom application is performed. This is a mandatory step (see Media file 1). In ghosting, the surgeon holds the vacuum cup in front of the perineum in the same angle and position expected once the extractor has correctly been applied to the fetal head. This application is an exact parallel to the ghosting or phantom application procedure followed for a forceps operative delivery. The phantom application forces the clinician to make an additional check of fetal position and fetal station and establishes the correct instrument orientation. It also imposes a brief pause in the procedure, allowing the surgeon to mentally review the conduct of the planned operation. If uncertainty exists concerning the position, station, or flexion of the presenting part, a pelvic examination is repeated or an abdominal and/or transperineal real-time ultrasonographic scan is performed prior to applying the instrument.
• Insertion: The cup is lubricated with sterile lubricant or surgical soap. If a soft cup is used, it may be partially collapsed by the operator's hand and introduced through the labia. Rigid cups are turned sideways, the labia are gently spread, and the device is slipped into the vagina and then positioned against the fetal head.
• Correct application
• • Once what is believed to be a proper cup application is established, sufficient vacuum to fix the cup to the fetal head is applied. A check of cup placement follows (ie, mid sagittal, over pivot point, no maternal tissue included). The appropriate vector of traction is directed through the cranial pivot point. When the extraction cup is properly positioned, the fetal head will flex but neither twist obliquely nor extend as force is applied. 
  • The center of the vacuum cup is positioned over the point of cranial flexion or the pivot point. Anatomically, the pivot point is an imaginary spot over the sagittal suture of the fetal skull, located approximately 6 cm posterior to the center of the anterior fontanel or 1-2 cm anterior to the posterior fontanel. When properly placed with its center over the pivot point, the edge of a standard 60-mm cup lies approximately 3 cm or 2 fingerbreadths behind the center of the anterior fontanel in the midline over the sagittal suture (see Media file 2). In VE operations, the anterior fontanel becomes the principal reference point for checking the instrument application. Access to the posterior fontanel is usually partially blocked once the extractor cup is correctly place, rendering this familiar landmark unusable.
  • The further the cup center is displaced from the midsagittal position on the fetal head over the cranial pivot or flexion point, the greater the failure rate of the of the fetal head extraction. This is because traction with an oblique application results in progressive cranial deflexion or twisting (see Media file 3). This actually increases the work of the extraction by presenting an ever larger cranial diameter to the birth canal.⁵⁰
  • Note that real time ultrasonography has been successfully used to verify proper cup placement, as was previously discussed.⁵⁷
•  Traction
• • Once the surgeon is convinced of an appropriate placement, full vacuum is applied (550-600 mm Hg) and traction follows, paralleling the uterine contractions. Waiting an arbitrary period of time for a chignon to form is not necessary.³¹ The direction of pull on the traction handle changes as the fetal head transverses the pelvic curve (see Media files 4-5). Traction efforts are timed to coincide with uterine contractions. Once the contraction begins, the vacuum pump is actuated until the appropriate degree of vacuum pressure is reached. Traction by the surgeon follows with the force applied to the extractor handle gradually increased to the desired level, paralleling the rise in uterine force generated by the contraction.  
  • As force is applied, the surgeon recruits maternal bearing down efforts to accompany in the traction effort. As each contraction wanes, the tension on the extractor handle is relaxed. Attempting traction without the assistance of maternal bearing down efforts and/or a uterine contraction is inappropriate. These techniques simply predispose to failure and risk a fetal scalp injury from a pop-off. 
  • In the relaxation phase between contractions, the vacuum can either be maintained or reduced to less than 200 mm Hg. Both techniques are acceptable. Continuous vacuum throughout the procedure and intermittent vacuum with the vacuum released between contractions, have been studied in a randomized trial.⁹ No differences exist between groups with regard to the speed of delivery, rates of instrument failure, or maternal or fetal outcomes. Thus, the use of either technique is at the discretion of the surgeon. Nonetheless, based on the author’s experience, they favor vacuum reduction.
  • During traction, the surgeon should place the nondominant hand within the vagina, with the thumb on the extractor cup and one or more fingers on the fetal scalp. So positioned, the accoucheur follows the descent of the presenting part and can judge the appropriate and changing angle for traction while gauging the relative position of the cup edge to the scalp. This helps to detect cup separation.
  • Ideally, descent of the presenting part should begin with the initial traction effort, assuming proper coordination with the maternal bearing down efforts and the uterine contractions. If the operator is uncertain that descent has occurred, a maximum of 2 additional tractions may be attempted.⁶ The failure to clearly achieve fetal station after properly timed traction in the correct vector of force mandates prompt reassessment of the procedure both in terms of technique and desirability. Recurrent tensioning of the scalp without descent of the presenting part (negative traction) predisposes to cup pop-offs and is believed to increase the risk for scalp injury.

Limits to effort

An important issue in the conduct of any instrumental delivery is the force used in the extraction procedure. Studies performed with forceps and rigid-cup extractors reveal similar findings. In approximately 85% of births, delivery occurs with 4 or fewer pulls.

Table 2. Number of Tractions Required in Vacuum Extraction and Forceps Deliveries*

A number of aspects of best practice in the use of the ventouse are not established. The most important are (1) the number of acceptable pop-offs permissible and (2) the number of allowable tractions without apparent process that can occur before declaring a case a failure. The extant literature is inconsistent in this regard and does not provide clear direction. Thus, the clinician is left to consider simply the opinions of various authors and the reports from several series when certain protocols of usage were followed. 

The rules of reasonable behavior apply. If cranial delivery is imminent, abandoning a procedure in favor of a cesarean delivery simply because the fourth or fifth pull has occurred is inappropriate. In contrast, procedures leading to cup pop-offs or procedures requiring multiple traction efforts with limited progress are best abandoned. Optimistic beliefs in continued but very slow progress usually represent no progress at all. As the accoucheur strains to overcome what is usually a degree of disproportion, he or she is tempted to try just one more traction (or several more). More dangerously, the clinician may simply abandon the VE effort without additional evaluation and apply a forceps in the effort to achieve a vaginal delivery.

Special applications

At cesarean delivery, a thin lower-uterine segment, combined with a narrow or deep pelvis, predisposes to lacerations or to an extension of the original incision when a manual extraction of the fetal head is performed. Similarly, a high transverse lie may prove difficult to extract at a cesarean without extension of the original incision or substantial traction. Various instruments (forceps, Murless vectus blade, VE) are used to expedite such difficult cesarean deliveries.

The application of a VE during a cesarean delivery is a question of practicality. Deeply engaged fetal heads are best elevated from below by an assistant and delivered primarily by manual extraction. This may obviate the need for the application of any instrument.

Alternatively, manual displacement can free the head from deep in the pelvis and rotating it into a position where an instrumental application is possible. However, the best use for VE at cesarean delivery is for fetal heads that remain high in the uterus after membrane rupture and are not easily delivered into the uterine incision despite fundal pressure. This commonly occurs with either a transverse lie or the second of twins. Once the fetal head is manipulated into the uterine incision, using the VE to grasp the fetal head is usually easy. This avoids the need for a breech extraction and potentially averts an extension of the original myometrial incision. No data exist indicating any specific advantage to VE over forceps or the vectus blade (Murless instrument) for instrumental extractions during a cesarean.

Sequential instrument use

Sequential instrument use (forceps operations followed by VE, or vice versa) is controversial. Recent studies by Gardella²¹ and Towner⁴⁹ involving large numbers of cases report that sequential operations are associated with an increased risk for fetal intracranial hemorrhage (ICH), exceeding the risk when either forceps or VE are used alone. Similar data concerning an enhanced risk from combined procedures comes from review of the 1998 Food and Drug Administration (FDA) advisory paper on VE,¹¹ as well as other sources. However, this has not been the finding in all series.⁷ Additional discussion of intracranial injuries and instrumental delivery occurs in Choice of Instrument.

The authors believe that the risk is one of degree. When one type of instrument is applied and fails, no absolute prohibition exists to trying a different device. Case choice is critical. The most appropriate cases in which to change instruments are those in which technical problems, such as a malfunctioning hand pump or a misapplied vacuum cup, are suspected to be the cause of failure. The least desirable cases are those in which multiple tractions or pop-offs occur following a correct application and appropriate traction but without descent of the presenting part.

Injuries from multiple instrument use are most likely when a degree of unrecognized feto-pelvic disproportion is present and, despite difficulty, the clinician cannot refrain from pursuing vaginal operative delivery. The failure of the original procedure should immediately suggest relative disproportion or faulty technique and inspire immediate caution and reassessment, not the resolve to triumph over difficulty.

Operative vaginal deliveries in which one type of instrument is applied after the failure of another (such as an effort at vacuum extraction following an unsuccessful trial of forceps or, more commonly, the application of forceps following a failed vacuum extraction) must not be routine. These procedures must remain restricted to highly experienced physicians who have a clear understanding that of the greater risk of birth injury in such operations.

BIRTH INJURIES

Section 8 of 13  

• Authors and Editors
• Introduction and History
• Prerequisites for Vacuum Extraction
• Indications for Vacuum Extraction
• Contraindications to Vacuum Extraction
• Design of the Vacuum Extractor
• Vacuum Extraction Technique
• Birth Injuries
• Vacuum Extraction versus Forceps
• Conclusion
• Acknowledgments
• Multimedia
• References

Neonatal Injury

No type of assisted delivery is entirely free of risk for both mother and infant.^{18, 33, 41, 55, 58} The issues are the magnitude of the risk and the alternatives available for delivery once the natural processes fail. The reported incidence of fetal death or severe fetal injury from vacuum extraction (VE) is low, ranging from 0.1-3 cases per 1,000 extraction procedures. Clinically diagnosed scalp injuries occur largely because of the physics of vacuum extraction. As the vacuum force is applied, the extractor draws the fetal scalp into the body of the cup. This produces the characteristic mound of scalp tissue and edema, the chignon, that may be identified after an extraction. Traction also tensions the scalp against its attachments to the fetal skull, drawing it in the direction of the cup. These effects predispose to bleeding within the substance of the scalp.

The 2 major types of scalp injury are the common, but clinically unimportant, cephalohematomas and the relatively rare, but potentially life threatening, subgaleal hemorrhages (see Media file 6). Scalp bruising or lacerations and retinal hemorrhages are additional, usually insignificant fetal risks of extraction procedures. 

When either radiographic or ultrasonic studies of the CNS are routinely performed on newborns who were delivered spontaneously or by instrumental assistance, minor trauma to the scalp, linear occult cranial fractures and subarachnoid bleeding are discovered more frequently than their clinical signs and symptoms suggest.^{47, 45} A small series by Whitby using MRI studies in term asymptomatic newborns reports similar findings.⁵⁶

These observations and the difficulties in clinically distinguishing cephalohematomas from edema or in diagnosing small subgaleal bleeds indicate that investigations based solely on clinical presentation and physical examinations miss many asymptomatic neonates with some degree of birth-related trauma. The data also indicate that the large proportion of these asymptomatic events are not of clinical importance. Drawing from the Towner data, the major intervening risk for these occult injuries is probably the combination of labor and the cranial distortion normal in vaginal delivery.⁴⁹

Subgaleal and subaponeurotic hemorrhage

The most feared complication of VE is hemorrhage in the subgaleal (SG) or subaponeurotic space from rupture of the emissary veins.^{20, 38, 33, 50, 58} This condition is potentially life threatening, with a mortality rate reported as high as 20%. Approximately half of all SG hemorrhages are related to VE. Most of the rest are associated with forceps operations. Less commonly, SG bleeds follow spontaneous deliveries. The reported incidence of clinically identified or symptomatic SG hemorrhages ranges from 6-50 per 1,000 VE operations. These rates almost certainly are overestimates and do not reflect the rates of injury in modern practice when soft-cup extractors are used and strict protocols for application and the limitation of effort are followed.

SG bleeding was not observed in the large number of cases included in several major clinical reports in recent years.^{6, 45} No SG cases were reported in the large vacuum extraction meta-analysis by Johanson.²⁵ Also, In the 2007 report by Simonson and coworkers, of the 913 VE procedures no instances were reported in which the neonates were routinely screened postdelivery by cranial radiography.⁴⁵ Further, the French study by Baume and coworkers involving 845 VE operations also did not report any clinically identified cases of SG hemorrhage.⁶ These data document the rarity of such clinically significant  severe scalp injuries. These results also emphasize that when strict technical guidelines for the performance of VE operations are used, the risk of symptomatic SG hemorrhage while never zero is, nonetheless, quite small.
 
In the experience of the authors, SG bleeding is mostly likely when excessive force, multiple pop-offs, prolonged cup application times or serial instrumentation with VE and forceps has occurred. However, recall that serious cases of SG bleeding have followed outwardly uneventful extractions. Thus, even adherence to protocol may not avoid all cases. Because of the small but significant risk of SG bleeding, the attending pediatric personnel should be informed whenever a VE operation has occurred, regardless of the immediate condition of the neonate. SG hemorrhages are dangerous because the clinical signs and symptoms may not be clinically apparent until some hours postpartum. Thus, serial observation is required.

Scalp bruising and lacerations

Ecchymoses and, uncommonly, scalp slough or lacerations can follow VE. Most of these injuries occur when the recommended 30-minute (some authors favor 20 minutes) limit to total cup application is exceeded or efforts are made at cup rotation.
 
The ventouse is not a rotating instrument. Attempts at cup rotation simply foster cup displacement, loss of station, or scalp injury. Under traction, the fetal head rotates automatically as descent occurs. If the clinician feels an obligation to assist or hasten this process, then manual rotation of the head (not the cup) can accompany the extraction. Normally, this is not required and efforts at rotation should never be forced.
 
Comments regarding risk

The risk from vacuum extraction operations arises from 2 basic sources:

• An inherent small risk intrinsic to the procedure that is independent of the operator and reflects the physics of how the extractor grasps the fetal scalp and produces cranial traction.
• By far more important is the risk that arises from the actual conduct of the operation (ie, traction to scalp, perineal pressure). This procedural or operative risk reflects the skill of the operator, the fetopelvic size relationship, the orientation of the fetal head, the resistance of the maternal soft tissues, and the station of the fetal head at the commencement of the operation, among other factors. These latter components of risk are subject to modification by the accoucheur by the careful choice of cases, judicious use of traction in the appropriate vector of force, performance of episiotomy or not, and, most importantly, knowing when to desist from additional efforts if progress is not prompt. Most fetal injuries occur when multiple cup displacements occur, the extraction proves prolonged, or a shoulder dystocia complicates the delivery.

As with all types of instrumental delivery, not all risks are eliminated by any established method. However, vacuum operations are demonstrably as safe for the fetus as forceps procedures and because of the unique method of grasping the fetal head, the technique has certain advantages vis a vis forceps in terms of limiting the potential for maternal injury.
 
In summary, when used under protocol with conscientious attention to detail, the vacuum extractor is a safe instrument.

Long-term Neonatal Outcomes

Studies evaluating both the general safety and the long-term neurologic sequelae of instrumental delivery reported no important differences in outcome between children delivered spontaneously versus those delivered by either VE or forceps.^{52, 40, 26, 55, 10, 45, 39} Cohorts of children delivered by VE-assisted procedures versus spontaneous deliveries have been studied at intervals of up to 18 years.^{26, 40} These children scored similarly in scholastic performance, speech, ability for self-care, and neurologic status. These latter long-term studies, though limited in total patient number, provide reassurance of VE safety.

Maternal Injury

Vacuum extraction has a low rate of maternal injury in comparison with forceps operations or cesarean delivery. However, maternal injuries do occur. Such trauma cannot be disregarded in evaluating the risk of the procedure.⁶

Lacerations

Maternal perineal lacerations are common complications of all operative vaginal deliveries.⁶ Many tears are associated with episiotomy. Depending on series reflecting obstetric routines of perineal management and instrument use, the incidence of severe perineal lacerations (ie, third- and fourth-degree lacerations) during VE procedures ranges from 5-30%. Women who sustain vaginal lacerations in a previous delivery are at a significantly greater risk for a repeat laceration in subsequent deliveries. Women at greatest risk are those who experienced a laceration in the first delivery followed by another delivery combining both an instrumental delivery and an episiotomy. Delivery technique, skill, fetal bulk, prior scars, and instrument choice are important factors in perineal injury.^{14, 43, 24, 16, 17, 28, 19, 53, 27}

One area in which vacuum extractor has a clear advantage over forceps is the incidence of perineal trauma. Forceps operations are more likely to result in anal sphincter injury trauma than vacuum extractions. Episiotomy is an important risk factor. Electively incising the perineum predisposes to perineal lacerations and rectal injuries by direct extension. The authors favor the selective performance of episiotomy and only if maternal soft tissues impede the delivery process. In Europe, when an episiotomy is required, mediolateral (ML) incisions are preferred. ML episiotomies are less likely than median episiotomies (ME) to extend into the rectal sphincter or mucosa.¹⁶ However, the ML is harder to repair, is more likely to result in distortion of the perineum, and results in more pain in the puerperium. 

Episiotomy should not be routine and careful technique can often avoid tears, especially in multiparas. Best practice concerning whether to perform an episiotomy during an instrumental delivery, the type to use, and the timing is yet to be established. In the author's opinion, episiotomy is avoided when possible and, if required, the type depends on maternal anatomy.

Stress, urinary, and anal incontinence

Genetic predisposition, dystocia in labor, vaginal delivery, obstetric lacerations, multiparity, and probably the mode of delivery combine to result in both reversible and permanent injuries to connective tissues of the maternal pelvis. Injury to these support structures and to the rectum constitutes important and perhaps unavoidable risks of both labor and instrumental delivery.^{42, 48, 43, 51, 32}

The female pelvic viscera are suspended from above and supported from below. The intactness of the various support structures depends upon the integrity of their muscular, fascial, and neurologic constituents.

The upper suspensory structures are a complex of pseudoligamentous structures loosely termed pelvic ligaments. This connective tissue accompanies vascular structures into the pelvis to surround the cervix. The lower supports for the uterus are a musculofascial complex including the urogenital and pelvic diaphragms. The pelvic diaphragm principally consists of the levator ani muscle. The urogenital diaphragm is a complex of small muscles and accompanying connective tissue that extends from the central perineal body radially to attach to various bony and ligamentous sites in the pelvis.

Both labor and the process of passing the fetal body through the birth canal distort and injure these and other pelvic tissues. During parturition, pelvic ligaments and muscles are simply torn or otherwise disrupted and accompanying nerves are traumatized. Various spontaneous lacerations or episiotomy extensions account for additional injuries, especially to the rectal sphincter.

The issue is not whether vaginal delivery results in injuries to pelvic soft tissues. The question is the degree of the injury and the extent to which spontaneous postpartum healing or specific muscle strengthening exercises performed in the puerperium may ameliorate this damage. In terms of instrumental delivery, techniques that either reduce or avoid injury to pelvic supports and to the rectum are under study. Long-term, follow-up studies controlling for prepartum pelvic support status (eg, preexisting rectal dysfunction, urinary incontinence) as well as length of labor, type of anesthesia, clinically observed perineal trauma, and delivery method are required before changes in current practice can be confidently recommended.

Long-term follow-up studies controlling for prepartum pelvic support status, eg, preexisting rectal dysfunction and/or urinary incontinence, length of labor, anesthesia, clinically observed perineal trauma, and delivery method, are required before changes in current practice can be recommended.

VACUUM EXTRACTION VERSUS FORCEPS

Section 9 of 13  

• Authors and Editors
• Introduction and History
• Prerequisites for Vacuum Extraction
• Indications for Vacuum Extraction
• Contraindications to Vacuum Extraction
• Design of the Vacuum Extractor
• Vacuum Extraction Technique
• Birth Injuries
• Vacuum Extraction versus Forceps
• Conclusion
• Acknowledgments
• Multimedia
• References

Long-term debate amongst clinicians concerns when assisted delivery is appropriate and which instrument (vacuum extractor or forceps), is best.^{44, 50, 8, 36, 37, 54, 55, 27, 41, 58} In deciding to use one instrument over the other, the following factors are involved.

• Anesthesia: In general, low or outlet vacuum extraction (VE) operations are less uncomfortable for the mother than a forceps procedure from the same station. The meta-analysis reported by Johanson  observed a significant reduction in the requirement for anesthesia with VE operations in comparison with forceps deliveries.²⁷ With a willing parturient, an uncomplicated VE can occasionally be performed with either a local, pudendal, or no anesthetic.
• Instrument failure: VE operations have a higher failure rate than forceps procedures. The relative risk of failure with VE versus forceps operations is 1.69 (95% CI, 1.31, 2.19). The higher VE failure rate reflects a number of factors: poor instrument applications, incorrect vector of force in traction efforts, improper methods of applying traction, fetal malpositioning, poor choice of cases, and operator inexperience as well as the intrinsic inability of the vacuum extractor to exert as much force on the fetus as is possible with forceps.^{7, 2} The higher failure rate for VE operations is of concern in light of recent data regarding the risks of sequential instrument use when the application of forceps may follow a VE failure. Infants from sequential instrument deliveries have worse outcomes than procedures that are successful on first attempt.
• Maternal injury: Any instrumental delivery is associated with an increased risk of perineal/rectal injury versus the incidence of these complications following either a spontaneous or a cesarean delivery. A consistent finding in all reports is an increased incidence of perineal tears following forceps as opposed to VE deliveries.^{16, 17, 27, 24, 19, 14, 21}
• Fatal fetal injury: A study reported by Towner and coworkers collected mode of delivery and birth injury data from several large populations.⁴⁹ The report by Demissie and coworkers includes information from total United States births for 1995-8 (n= 11,939,388) as well as data from New Jersey (375,351).¹⁸ These large numbers permit statistical evaluation of mortality information as most other studies have too restricted numbers due to the low incidence of fatal injury. The results indicate that delivery by VE is least as safe as forceps delivery with fatal complications in both the studied cohorts statistically similar.    
• Other fetal injuries 
• • Facial nerve (VII) palsies are more common following forceps operations (4.5 per 1,000) than VE procedures (0.46 per 1,000).⁴⁹ However, these injuries are virtually always transitory and not of great clinical import. 
  • In the Towner series, infants delivered by VE had a significantly higher rate of intracranial hemorrhage (ICH) (including subdural and other cerebral bleeds), brachial plexus injuries, convulsions, and central nervous system depression versus infants delivered spontaneously. VE neonates are also more likely to need mechanical ventilation after delivery than spontaneously delivered infants. Similar findings were noted by Wen and coworkers in a series of 305,391 deliveries.⁵⁵
  • However, in the Towner report, which included 584,340 total deliveries, no significant differences were reported in the risk for the more severe neonatal injuries, including ICH, between infants delivered by cesarean delivery during labor (0.25 per 1,000) and infants delivered by either VE (0.15 per 1,000) or forceps (0.26 per 1,000) alone.
• Table 3. Incidence of Fetal Intracranial Hemorrhage (n=584,340)⁴⁹
  
  

  Mode of Delivery	Incidence of ICH
  Cesarean delivery with no labor Spontaneous vaginal delivery	1 per 2,750 1 per 1,900
  Cesarean delivery during labor Vacuum-assisted vaginal delivery Forceps-assisted vaginal delivery	1 per 907* 1 per 860* 1 per 664*
  Cesarean delivery after failed vacuum or forceps-assisted delivery	1 per 334

  
  *Differences not statistically significant

Comments

• These and other data implicate the events of labor and the fact of vaginal delivery, as opposed to any specific delivery instrument, as a major factor in the etiology of serious intracranial injuries. Note that in this series only cesarean delivery without labor is protective, resulting in a reduced risk for ICH.
• In the Demissie  study, infant deaths (0-364 days) for the United States cohort were essentially equal for infants delivered spontaneously (n=10,137,144), by forceps (n=435,339) or by VE (n=891,340) attesting in part to the safety of VE operations.¹⁸ 

Other clinical considerations

In general, when an emergency delivery is required and a vaginal operative trial is elected, greater success and less danger result when a delivery instrument is chosen based on prior operator experience and proven skill. Other important considerations include:  

• Presumed fetal jeopardy and nonreassuring monitoring: In presumed fetal jeopardy at a low station (+2/5 +/- cm), many prefer to apply forceps rather than the vacuum. However,  the differences in safety or speed between these instruments are minimal. Either the vacuum extractor or the forceps is appropriate in these urgent cases, depending on the comfort level of the clinician. 
• Maternal parity: Forceps-related lacerations and extensions are less likely among multiparas.
• Shoulder dystocia: The risk is increased with VE. This may relate to the physics of extraction, specifically the vector of force generated by the VE versus the forceps. VE may also be preferentially used as a trial instrument when fetal bulk is believed to be large and assistance in the second stage is required.
• Heavy cranial molding and caput: When the situation is without exigency, a number of issues deserve consideration. The forces of labor normally result in some cranial molding and often caput. The combination of molding and caput succedaneum formation obscures traditional landmarks. Even experienced clinicians may have difficulty in assessing fetal position and fetal station in some cases. Careful attention to palpation of the cranial fontanels, suture lines, orbital ridges, or the fetal ear helps establish the correct cranial orientation and cranial station.
  
  In difficult cases, real-time ultrasonographic scanning is useful in evaluating fetal cranial positioning and station, particularly in occiput posterior positions. Visualization of the fetal orbits, cranial anatomy, position of the fetal spine, and other anatomic landmarks is usually easy, which verifies the position. If the fetal head is heavily molded, the cranial bones overlap, and the presenting part remains high, disproportion is likely. In this setting, no attempt at an instrumental delivery is appropriate and a cesarean delivery is the best management (see Media file 7).
• Antibiotics: No convincing data exist to support the routine administration of antibiotics to the mother either before or after an instrumental delivery.³⁰ Such therapy is not recommended in the absence of other standard indications.
• Prematurity (<36 wk): The use of any instrument to assist delivery of a premature infant is controversial. Older data suggest that gentle assisted delivery of the fetal head on the perineum using a classic forceps might reduce cranial trauma. However, this traditional application has unimpressive literature support. As the inherent risks of fetal intracranial or scalp hemorrhage are greater in premature infants than in full-term infants, the vacuum extractor is relatively contraindicated for applications in infants younger than 36 weeks. Yet, as data on this issue are both limited and often anecdotal, this contraindication cannot be absolute. If an extractor is chosen for a preterm pregnancy, a soft-cup design is preferred.
• Breech presentations: In breech presentations, VE use is contraindicated. A vaginal breech delivery is a potential indication for the application of forceps. Either Piper or Kjelland forceps are appropriate for the after-coming head.
• Cesarean delivery: As previously reviewed, VE may assist in extraction. The best use is when the fetus assumes a transverse or high oblique lie after rupture of the membranes.
• Multiple gestations: The vaginal delivery of a second cephalic-presenting twin is often a good case for a vacuum extractor. Such extractions are usually easy because of dilation of the birth canal following the delivery of the first infant. A VE operation at cesarean delivery may obviate the need for extraction of the second twin and avoid an extension of the cesarean wound. Here, any type of VE is acceptable.

Choice of instrument

Practice suggestions: The accoucheur must carefully consider the fetal condition, available resources, extent of analgesia, likelihood of maternal cooperation, and personal skill level when choosing the instrument for operative vaginal delivery. Recommendations are as follows: 

• Outlet- and low-pelvic operations (rotation <45°): With adequate analgesia, the vacuum extractor and forceps are equivalent instruments. If a VE is chosen, any cup type is acceptable.
• Rotations greater than 45° and midpelvic operations: For heads in transverse position, the appropriate cup choices include an occiput posterior (OP) metal cup or a rigid plastic or M-cup design. Forceps may also be used for these positions, but these operations are restricted to experienced physicians only. Usually, first attempting manual rotation is prudent, as this may prove successful, easing the subsequent instrumental delivery.
• Other procedures: Instrumental deliveries that do not involve significant cranial asynclitism are equally well managed by any vacuum instrument. If an extraction is performed from a direct OP position, appropriate choices include an OP metal cup or a rigid plastic or M-cup OP design. Forceps may also be applied to OP either for a direct "face to pubes" pull or for a rotation. Both the pull and a rotation can prove difficult and risk maternal soft-tissue injury. Forceps rotations from OP to OA are another example of procedures that are reserved for the experienced accoucheur.

CONCLUSION

Section 10 of 13  

• Authors and Editors
• Introduction and History
• Prerequisites for Vacuum Extraction
• Indications for Vacuum Extraction
• Contraindications to Vacuum Extraction
• Design of the Vacuum Extractor
• Vacuum Extraction Technique
• Birth Injuries
• Vacuum Extraction versus Forceps
• Conclusion
• Acknowledgments
• Multimedia
• References

Opinions for standard VE procedures

The vacuum extractor is an effective and safe device for assisted vaginal delivery and an important addition to the modern obstetrical armamentarium. Proper education in the use of these devices is mandatory.  The clinician must treat this instrument with respect to maximize the possibilities of its success while limiting the risks of maternal or fetal injury. 

• Properly conducted trials of instrumental delivery following an adequate trial of labor have a limited but continued place in clinical practice. Trials are only conducted by the experienced, in situations when the possibility of success is believed to be high, and when concomitant preparations for a possible cesarean delivery are underway.
• Routine notification of the pediatrician or the newborn attendants that an extraction operation has been performed is recommended to assure appropriate postoperative observation of the neonate.
• Trauma to the maternal birth canal and perineum following instrumental delivery damages maternal pelvic nerves and fascial supports and can disrupt the anal sphincter, resulting in permanent pelvic floor injury or rectal dysfunction. The available data, while incomplete, prompts caution in instrumental deliveries to avoid episiotomy and perineal injury when possible.
• The likelihood of serious infant injury is increased when multiple or excessive efforts at extraction are performed or either the forceps or a vacuum extractor is attempted following a failed operation with the alternative instrument. Sequential instrument use is restricted to selected cases conducted only by highly experienced surgeons.

Routine practice

These recommendations are based on the authors' experience and on large clinical series that reported a low incidence of injury when similar rules were followed.        

• Obtain informed consent.
• Limit the number of tractions with the VE to 4 or 5.
• Limit unintended cup detachments or pop-offs to no more than 2 or 3 with soft cups and 1 or 2 with either metal or rigid plastic cups.
• Require advancement of the presenting part with the initial or, certainly, the second traction.
• Restrict the overall duration of the procedure to less than 30 minutes (note that some clinicians propose 20 min). Reduce vacuum between traction efforts.
• Avoid sequential use of the vacuum extractor and forceps.
• Abandon any procedure that proves difficult.
• Dictate all procedures

ACKNOWLEDGMENTS

Section 11 of 13  

• Authors and Editors
• Introduction and History
• Prerequisites for Vacuum Extraction
• Indications for Vacuum Extraction
• Contraindications to Vacuum Extraction
• Design of the Vacuum Extractor
• Vacuum Extraction Technique
• Birth Injuries
• Vacuum Extraction versus Forceps
• Conclusion
• Acknowledgments
• Multimedia
• References

The authors and editors of eMedicine acknowledge the contributions of previous authors Christian S Pope, DO and Zaya Darouian to the development and writing of the original article concerning vacuum delivery. Further, the editorial and research assistance of Carolyn Taugher in the preparation of the current paper is gratefully recalled. 

MULTIMEDIA

Section 12 of 13  

• Authors and Editors
• Introduction and History
• Prerequisites for Vacuum Extraction
• Indications for Vacuum Extraction
• Contraindications to Vacuum Extraction
• Design of the Vacuum Extractor
• Vacuum Extraction Technique
• Birth Injuries
• Vacuum Extraction versus Forceps
• Conclusion
• Acknowledgments
• Multimedia
• References

Media file 1:  Ghosting or phantom application of vacuum extraction.
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Media file 2:  Cranial flexion or pivot point.
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Media file 3:  Incorrect sites for cup placement.
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Media file 4:  Changing vector of traction.
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Media file 5:  Lateral view of maternal pelvis. Pelvic axis/curve is demonstrated.
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Media file 6:  Scalp cross-section and hemorrhage sites.
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Media file 7:  Digital evaluation of cranial molding.