AUTHOR AND EDITOR INFORMATION

Section 1 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Follow-up
• Miscellaneous
• Multimedia
• References

INTRODUCTION

Section 2 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Follow-up
• Miscellaneous
• Multimedia
• References

Background

The most common complication of pregnancy is spontaneous abortion, which occurs in an estimated 10-15% of pregnancies. Spontaneous abortion is categorized as threatened, inevitable, incomplete, complete, or missed. Spontaneous abortion can be further classified as sporadic or recurrent. Inevitable abortion is defined as bleeding of intrauterine origin with continuous and progressive dilation of the cervix but without expulsion of conception products before the 20th week of gestation.

Pathophysiology

The timing of a spontaneous abortion suggests its pathophysiology. Genetic anomalies (trisomies); hormonal abnormalities; and infectious, immunologic, and environmental factors usually result in first-trimester loss. Anatomic factors usually are associated with second-trimester loss.

Frequency

United States

Many pregnancies are not viable, with an estimated loss of 50% before the first missed menstrual period. These pregnancies usually are not clinically recognized. Classic spontaneous abortion is defined as a clinically recognized (ie, by blood test, ultrasound) pregnancy loss before the 20th week of gestation. Spontaneous abortion occurs in an estimated 10-15% of pregnancies.

Mortality/Morbidity

Surveillance data of pregnancy-related deaths from 1987 through 1990 revealed a total of 1459 deaths in the US. Of these deaths, spontaneous and induced abortions accounted for 5.6%.

Race

Surveillance data for pregnancy-related deaths (1987-1990) demonstrated that more black mothers died after ectopic pregnancies and abortions, both spontaneous (14%) and induced (7%), than white mothers (8% and 4%, respectively).

Age

• Age and increased parity affect the risk of a miscarriage. Twelve percent of pregnancies terminate in miscarriage in women younger than 20 years; frequency increases to 26% in women older than 20 years.
• Age primarily affects the oocyte. When oocytes from young women are used to create embryos for transfer to older recipients, implantation and pregnancy rates mimic those seen in younger women, and the number of miscarriages and chromosomal anomalies decreases. This phenomenon suggests that the uterus is not responsible for poor outcomes in women of advanced reproductive age.

CLINICAL

Section 3 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Follow-up
• Miscellaneous
• Multimedia
• References

History

• Inevitable and incomplete miscarriages present in a similar clinical fashion and have similar treatment. The patient history should include the following:
• • Last menstrual period (LMP)
  • Estimated length of gestation
  • Ultrasound results, if previously performed
  • Bleeding
    • Degree
    • Duration
    • Presence or passage of tissue
    • Bleeding may be roughly quantified by the number of pads soaked per hour or day. An average pad absorbs approximately 20-30 mL of blood.
  • Previous spontaneous or elective abortions

Physical

• Vital signs should be within reference ranges unless infection is present or hemorrhage has caused hypovolemia. Preexisting anemia may make a patient more susceptible to hypovolemic shock.
• Uterine contractions may cause intermittent, progressive abdominal cramping that produces cervical effacement and dilation.
• The cervix is effaced and dilated on pelvic examination. The amniotic sac may be seen bulging through the cervix, or it may be ruptured. Amniotic fluid may be present in the vagina. The uterus is enlarged and soft on bimanual examination.

Causes

• Genetic factors account for approximately 5% of spontaneous abortions. One meta-analysis found that a chromosomal abnormality occurs in 49% of spontaneous abortions. Autosomal trisomy was the most commonly identified anomaly followed by polyploidy and monosomy X.
• Anatomic: Congenital or acquired anatomic factors are reported to occur in 10-15% of women with recurrent spontaneous abortion.
• • Congenital anatomic lesions include müllerian duct anomalies (eg, septate uterus, diethylstilbestrol [DES]-related). Müllerian duct lesions usually are found in second-trimester pregnancy loss. Anomalies of the uterine artery with compromised endometrial blood flow are congenital.
  • Acquired lesions include intrauterine adhesions (synechiae), leiomyoma, and endometriosis.
• Endocrine factors potentially contribute to recurrent abortion in 10-20% of cases.
• • Luteal phase insufficiency (ie, abnormal corpus luteum function with insufficient progesterone production) is implicated as the most common etiologic factor in endocrine abnormalities contributing to spontaneous abortion.
  • Hypothyroidism, hypoprolactinemia, poor diabetic control, and polycystic ovarian syndrome are recognized contributing factors to pregnancy loss.
• Infectious
• • A presumed infectious etiology may be found in 5% of cases.
  • Bacterial, viral, parasitic, fungal, and zoonotic infections are associated with recurrent spontaneous abortion.
• Immunologic
• • Immunologic factors may contribute to as many as 60% of recurrent spontaneous abortions.
  • Both the developing embryo and trophoblast may be considered immunologically foreign to the maternal immune system.
  • Antiphospholipid antibody syndrome generally is responsible for more second-trimester pregnancy loss than first-trimester loss.
• Miscellaneous
• • Miscellaneous factors may account for as many as 3% of recurrent spontaneous abortions.
  • Many other contributing factors are implicated in sporadic and recurrent spontaneous abortions. Environment, drugs, placental abnormalities, medical illnesses, and male-related causes are noted.

DIFFERENTIALS

Section 4 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Follow-up
• Miscellaneous
• Multimedia
• References

WORKUP

Section 5 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Follow-up
• Miscellaneous
• Multimedia
• References

Lab Studies

• Complete blood count with differential
• Blood type and Rh
• Qualitative and quantitative beta-human chorionic gonadotropin
• Factor XIII and fibrinogen

Imaging Studies

• Ultrasound is the most accurate diagnostic modality in the confirmation of a viable pregnancy during the first trimester.
• Fetal heartbeat should be detected upon endovaginal ultrasound by the fifth week of gestation. The presence of fetal cardiac activity in women with bleeding in early pregnancy has been noted to have a sensitivity of 97% and a specificity of 98% for fetal survival to the 20th week of pregnancy.
• Sonographic signs suggestive of a nonviable pregnancy include the following:
  • Irregular gestational sac (eg, gestational sac >25-mm mean sac diameter [MSD] on transabdominal ultrasound and >16-mm MSD on endovaginal ultrasound without a detectable embryo)
  • A nonliving embryo (embryo without a heartbeat)
  • Abnormal hyperechoic material within the uterine cavity
• Sonography can identify presence of a subchorionic hematoma (bleeding between the endometrium and the gestational sac).
• • Subchorionic hemorrhage is the most commonly identified source of first-trimester bleeding, appearing on sonography as a crescent-shaped hypoechoic area next to the gestational sac.
  • Subchorionic hemorrhage encompasses a spectrum of sonographic findings. Subchorionic fluid can be classified in relation to gestational sac size and length of gestation. Subchorionic bleeding is present when pulsation of the subchorionic fluid is noted.
  • Size of the subchorionic hemorrhage should be taken into consideration, as greater size relates to an increased risk of spontaneous abortion. Subchorionic fluid and bleeding, in combination with clinical bleeding, is associated with embryonic death. Also, presence of a subchorionic hemorrhage with fetal cardiac activity is associated with an increased rate of spontaneous abortion. Subchorionic bleeding can be demonstrated using color Doppler imaging.
• Sonographic diagnosis of early pregnancy failure should be considered in relation to the developmental stage.
• • Subclinical or preclinical loss: This occurs within the first 2 weeks after conception. No sonographic evidence of pregnancy exists at this stage.
  • Loss at 5-6 weeks: Loss at this stage is based upon gestational sac characteristics. Abnormal gestational sac size is the most reliable indicator of abnormal outcome. The gestational sac should be 5-mm MSD by the fifth gestational week. An abnormally large gestational sac, as determined by high-frequency endovaginal sonography (HFEVS), is observed when the MSD is more than 8 mm without a demonstrable yolk sac or is more than 16 mm without a demonstrable embryo (see Image 1).
  • Loss at 7-8 weeks: Sonographic evidence is based upon demonstration of an abnormal embryo or gestational sac.
  • Loss from 9-12 weeks: Sonographic diagnosis of embryonic demise usually is made upon demonstration of an abnormal embryo. Sonographic evidence of an embryo lacking cardiac activity is the most specific indicator of embryonic demise.
• Caution is advised in the diagnosis of embryonic demise. Determination of whether the viewed structure is the embryo is critical, as no other morphologically recognizable structures other than a heartbeat exist at this stage of development. The embryo must be scanned thoroughly for evidence of a heartbeat.
• • Most recommendations call for 2 independent examiners to view the embryo, either concurrent with the ED visit or at follow-up.
  • Most sonographers recommend repeating the scan within 3-7 days to determine whether the embryo is developing normally.
  • Upon follow-up, a falling beta-human chorionic gonadotropin (hCG) level as well as abnormal fetal development confirms embryonic demise.
• Apply endovaginal ultrasound whenever possible to limit image distortion due to patient habitus or an overdistended bladder.

Procedures

• Pelvic ultrasound is a clinically useful tool in the evaluation of spontaneous abortion.
• • Transabdominal ultrasound of the pelvis provides an overall view of the pelvic structures. A full bladder is required as a sonographic window.
  • Endovaginal ultrasound gives a detailed view of the endometrium, ovaries, adnexa, and cul-de-sac. An empty bladder is preferred.

TREATMENT

Section 6 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Follow-up
• Miscellaneous
• Multimedia
• References

Prehospital Care

• Maintain routine universal precautions in view of potentially heavy vaginal bleeding.
• If tissue has been passed, advise the patient to bring the material to the hospital for evaluation.

Emergency Department Care

• The goal of treatment is evacuation of the uterus to prevent complications (eg, further hemorrhage, infection).
• All patients with vaginal bleeding of any etiology should receive care that includes the following:
• • Determination of hemodynamic stability and treatment of instability
  • Determination of pregnancy status (qualitative and quantitative)
  • Pelvic ultrasonography may be useful in clinically classifying spontaneous abortion. Determination of Rh status and hematocrit usually is indicated.

Consultations

• Consult obstetrics and gynecology (OB/GYN), especially for difficult diagnoses and follow-up care.

FOLLOW-UP

Section 7 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Follow-up
• Miscellaneous
• Multimedia
• References

Further Inpatient Care

• If bleeding cannot be controlled in the ED, transfer the patient to the operating room (OR) for examination under anesthesia and for uterine evacuation.

Complications

• Potential complications include septic abortion and hypovolemic or septic shock.

Prognosis

• The prognosis for a successful pregnancy depends upon the etiology of the previous spontaneous abortion(s).
• • Correction of an endocrine abnormality in women with recurrent abortion has the best prognosis for a successful pregnancy (>90%).
  • In women with an unknown etiology of prior losses, the probability of achieving successful pregnancies is 40-80%.
  • The live-birth rate after documentation of fetal cardiac activity at 5-6 weeks of gestation in women with a history of 2 or more unexplained spontaneous abortions is approximately 77%.

Patient Education

• Advise patients to return to the ED upon occurrence of symptoms, including the following:
• • Profuse vaginal bleeding
  • Severe pelvic pain
  • Temperature above 38°C (100.4°F)
• The patient may experience intermittent menstrual-like flow and cramps during the following week. The next menstrual period usually occurs in 4-5 weeks.
• The patient can resume regular activities when able but should refrain from intercourse and douching for approximately 2 weeks.
• For excellent patient education resources, visit eMedicine's Pregnancy and Reproduction Center and Procedures Center. Also, see eMedicine's patient education articles Pregnancy, Bleeding, Miscarriage, Abortion, and Dilation and Curettage (D&C).

MISCELLANEOUS

Section 8 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Follow-up
• Miscellaneous
• Multimedia
• References

Medical/Legal Pitfalls

• Ectopic pregnancy
• • Endometrial shedding may occur with an ectopic pregnancy, thus clinically simulating a miscarriage. This misdiagnosis is the greatest potential pitfall.
  • An empty uterus upon ultrasound also may represent an ectopic pregnancy.

Special Concerns

• Offer grief counseling to all patients who have had a miscarriage.

MULTIMEDIA

Section 9 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Follow-up
• Miscellaneous
• Multimedia
• References

Media file 1:  Abortion, inevitable. This endovaginal ultrasonographic image demonstrates a subchorionic hemorrhage (SH) less than half the gestational sac size.
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Media type:  Image

Media file 2:  Abortion, inevitable. This flowchart details a diagnostic algorithm based on sonographic findings in early pregnancy, using high-frequency endovaginal sonography (HFEVS) of more than 5 megahertz (MHz). The flowchart incorporates clinical presentation (spotting vs clinical bleeding) with sonographic findings to aid in making clinical decisions. The algorithm continues in Image 3.
	View Full Size Image
Media type:  Graph

Media file 3:  Abortion, inevitable. This flowchart outlines a diagnostic algorithm based on the initial endovaginal sonographic finding of an intrauterine embryo. The chart incorporates fetal cardiac activity, crown-rump length (CRL), presence of subchorionic hemorrhage (SCH), and uterine or adnexal masses with clinical presentation (spotting vs bleeding) to aid in making clinical decisions.
	View Full Size Image
Media type:  Graph

REFERENCES

Section 10 of 10

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Follow-up
• Miscellaneous
• Multimedia
• References

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Article Last Updated: May 30, 2006