You are in: eMedicine Specialties > Radiology > OBSTETRICS/GYNECOLOGY Ectopic PregnancyArticle Last Updated: Jul 18, 2008AUTHOR AND EDITOR INFORMATIONSection 1 of 12
  Author: Douglas Bourgon, MD, Diagnostic Radiologist, Image Guided Therapeutics Douglas Bourgon is a member of the following medical societies: American College of Radiology, American Medical Association, American Roentgen Ray Society, and Radiological Society of North America Coauthor(s): Eric Outwater, MD, Professor, Department of Radiology, University of Arizona; Gregory J Balmforth, MD, Staff Physician, Department of Diagnostic Radiology, University of Arizona Medical Center Editors: Harris L Cohen, MD, FACR, Vice Chairman/Associate Chairman (Research Activities), Director, Division of Body Imaging, Professor of Radiology, Stony Brook School of Medicine; Visiting Professor of Radiology, Johns Hopkins School of Medicine; Bernard D Coombs, MB, ChB, PhD, Consulting Staff, Department of Specialist Rehabilitation Services, Hutt Valley District Health Board, New Zealand; Karen L Reuter, MD, FACR, Professor, Department of Radiology, Lahey Clinic Medical Center; Robert M Krasny, MD, Consulting Staff, Department of Radiology, The Angeles Clinic and Research Institute; Eugene C Lin, MD, Clinical Assistant Professor of Radiology, University of Washington Medical School Author and Editor Disclosure Synonyms and related keywords: ectopic pregnancy, ectopic gestation, extrauterine gestation, heterotopic pregnancy, metacyesis, eccyesis, interstitial ectopic, cornual ectopic, cervical ectopic, fimbrial ectopic, ovarian ectopic, ovarian pregnancy, peritoneal ectopic, tubal pregnancy, abdominal pregnancy, pelvic inflammatory disease INTRODUCTIONSection 2 of 12
  BackgroundEctopic pregnancy continues to be the leading cause of first-trimester maternal death. Although diagnosis and management have improved, the incidence of this disease has continued to climb since the US Centers for Disease Control and Prevention (CDC) started collecting data in 1970.1, 2 This increase is likely due to a continued rise in the prevalence of predisposing risk factors. Ectopic pregnancy has additional significance in that the associated mortality with this condition usually affects an otherwise healthy segment of the population. For excellent patient education resources, visit eMedicine's Pregnancy and Reproduction Center, Women's Health Center, and Sexually Transmitted Diseases Center. Also, see eMedicine's patient education article Ectopic Pregnancy. PathophysiologyThe physiologic and physical needs for normal growth and development of a fetus, including the decidual reaction, as well as hematologic and spatial requirements, are not provided outside of the uterus. The initial stages of gestation outside the uterus (ectopic pregnancies), however, do occur. Locations of such ectopic pregnancies include interstitial (cornual), cervical, and intra-abdominal sites. Most ectopic pregnancies, however, occur in the isthmic or ampullary portions of the fallopian tube.3 Compromise to the physiologic and physical needs for fetal growth when in an ectopic location usually results in fetal demise, either through rupture or involution of the gestational sac. Rupture of the ectopic pregnancy can place the mother at significant risk. Laboratory detection of beta–human chorionic gonadotropin (beta-HCG) is required for the diagnosis of an ectopic pregnancy. Although beta-HCG levels and their rate of increase may vary with ectopic pregnancies, a negative beta-HCG result effectively excludes the diagnosis of an intrauterine or extrauterine pregnancy. A chronic ectopic pregnancy, however, can have low beta-HCG levels. Although a positive beta-HCG result is highly specific for gestation, the analysis of beta-HCG levels is affected by the fact that at least 2 laboratory reporting standards are still used in practice. These include the International Reference Preparation (IRP), which is considered more pure than the previous Second International Standard (2IS). IRP values are approximately twice the value of the 2IS values.4, 5 Knowledge of the laboratory standard used at individual institutions is needed, particularly in evaluating the discriminatory levels of beta-HCG that are considered necessary to be reached before one can expect to image various structures (eg, gestational sac). FrequencyUnited StatesThe CDC estimated that approximately 108,800 ectopic pregnancies occurred in 1992.1 This number represented approximately 2% of all pregnancies. However, these estimates are considered conservative, because patients whose condition was diagnosed and managed exclusively through private offices would not have been included in that data set. Mortality/Morbidity
RaceNo race predilection for ectopic pregnancy is reported. SexWomen of childbearing age are affected. AgeWomen of childbearing age are affected. AnatomyApproximately 95% of ectopic pregnancies occur in the ampullary or isthmic portions of the fallopian tubes.2 About 2-5% occur as interstitial (cornual) ectopic pregnancies. The rare remaining locations include cervical, fimbrial, ovarian, and peritoneal sites, as well as previous cesarean section scars.2, 9 Clinical DetailsThe classic clinical triad of an ectopic pregnancy includes pain, vaginal bleeding, and an adnexal mass. The clinical triad, however, is nonspecific and present in less than 50% of ectopic pregnancies. The positive predictive value of the triad is only 14%.2, 4, 7
Preferred ExaminationTo diagnose an ectopic pregnancy, beta-HCG tests are required. A negative beta-HCG result effectively excludes the diagnosis of an ectopic or intrauterine pregnancy. In unstable patients, surgical evaluation and/or laparoscopy should be performed with or without culdocentesis. In patients with a stable clinical condition, transabdominal (TA) and endovaginal (EV) ultrasonography are performed. The demonstration of an intrauterine gestational sac effectively excludes the diagnosis of an ectopic pregnancy. A search for a possible ectopic pregnancy as part of a heterotopic pregnancy should be attempted. Medical management is often associated with follow-up imaging. Follow-up ultrasonography, along with follow-up beta-HCG levels, can be helpful if the diagnosis is unclear. A normal intrauterine pregnancy should demonstrate a 48-hour beta-HCG doubling time.4 Limitations of TechniquesTA and EV ultrasonography are recommended in all studies. In a patient in stable condition, a full bladder should be present as a proper TA ultrasonography window. In unstable patients in whom an expeditious diagnosis is needed, the time delay for the bladder to fill may be undesirable. TA and/or EV ultrasonography may be performed in these patients with an empty bladder. Both TA and EV examinations should still be performed with the acknowledgment of the limited, yet important, aspects of the TA portion of the examination. TA examination enables better evaluation of the superior uterus and superiorly positioned adnexa. It may aid detection of free peritoneal fluid and/or hemorrhage beyond the cul-de-sac.12 Transvaginal examination provides a detailed evaluation of the endometrial cavity and ovaries, but the high-frequency transducer that allows improved near-field resolution compared with TA examinations suffers from limited sound penetration (far-field imaging). MRI examination is time consuming and costly. Computed tomography (CT) scan findings are nonspecific in ectopic pregnancies and pose a hazard of ionizing radiation, which may be harmful to normal pregnancies. DIFFERENTIALSSection 3 of 12
Other Problems to Be ConsideredMissed abortion or blighted ovum RADIOGRAPHSection 4 of 12
FindingsNo clinically useful plain radiographic findings of ectopic pregnancy have been identified. The associated ionizing radiation poses a hazard if a normal intrauterine pregnancy is present. CT SCANSection 5 of 12
FindingsCT scan findings are nonspecific for ectopic pregnancy. The associated ionizing radiation poses a hazard if a normal intrauterine pregnancy is present. CT scanning is typically not an appropriate imaging modality to be used for the analysis of ectopic pregnancy. MRISection 6 of 12
FindingsMRI findings that can suggest an ectopic pregnancy include the presence of (1) a tubal gestational sac; (2) a tubal hematoma, which is a hematoma suggested by the ring sign (peripheral hyperintensity) on T1-weighted images; (3) tubal wall enhancement; and (4) an adnexal mass with hemorrhagic fluid in the peritoneum. Blood is suggested by the presence of high-signal-intensity fluid on T1-weighted images. Degree of ConfidenceMRI should be used only as a problem-solving tool in the patient who is in stable condition. This imaging modality is accurate in the characterization of tissue and in the detection and age determination of blood products. On MRI, high T1 signal intensity fluid in a fallopian tube is abnormal.13 With a positive beta-HCG result, this finding suggests an ectopic pregnancy. Subacute blood products associated with an adnexal mass are also indicative of an ectopic pregnancy. MRI can additionally delineate confounding adnexal findings seen on ultrasonography, such as follicular or corpus luteum cysts. False Positives/NegativesEarly intrauterine pregnancy or a missed abortion may be associated with normal MRI findings and thus falsely suggest an ectopic pregnancy. However, this scenario is not likely because of the high sensitivity of MRI in detecting associated fluid and blood products with true ectopic pregnancies. The appearance of an adnexal mass is not necessarily specific on MRI. Corpus luteum cysts and other masses may be confused with ruptured or unruptured ectopic pregnancy. False-positive results can be caused by abnormal tubal fluid or enhancement, as seen with pelvic inflammatory disease and simple hydrosalpinx; however, these findings should be correlated with a positive beta-HCG. ULTRASOUNDSection 7 of 12
FindingsFindings of an extrauterine ectopic pregnancy include the following:
Findings of an interstitial ectopic pregnancy include the following:
Degree of ConfidenceWhen correlating beta-HCG levels with ultrasonographic findings, it is important to take into account the standard of measurement. Both the 2IS and IRP systems are used to report beta-HCG values. An IRP value is approximately twice the corresponding 2IS value. With a positive beta-HCG level greater than 1000 IU/mL (2IS standard) or 2000 IU/mL (IRP standard), a gestational sac should be identifiable within the uterus on transvaginal sonograms.14, 16, 17 For TA scanning, a higher threshold of 1800 IU/mL (2IS standard) or 3600 IU/mL (IRP standard) should be used. An intrauterine pregnancy can be definitely diagnosed by the double-decidual-sac sign or by the demonstration of an embryo with a positive heartbeat. Cardiac activity should be identifiable in a fetus when it is found within a gestational sac during transvaginal ultrasonography with a mean diameter of 16 mm or a crown-rump length of 5 mm.18 The double decidual sac found with an early intrauterine pregnancy can be difficult to distinguish from the pseudogestational sac, which is seen in 20-50% of ectopic pregnancies. The double decidual sac is 2 concentric hyperechoic rings created by hypoechoic fluid between the decidua parietalis and the decidua capsularis. This sign is in distinct contrast to a single hyperechoic layer found with a pseudogestational sac (see Image 6). The lack of a yolk sac, the more-irregular contours, and the more-central location within the endometrial cavity also help in delineating a pseudogestational sac from an early intrauterine pregnancy. Further support of a pseudogestational sac can be demonstrated by the absence of low-resistance endometrial arterial flow on color Doppler ultrasonographic evaluation. The low pulsatility and the low-resistance flow are highly suggestive of an intrauterine pregnancy. This low-resistance flow should have a resistive index less than 0.6 or a peak systolic frequency of 0.8 kHz or greater.2, 19 The only specific sign of an ectopic pregnancy is the presence of a live extrauterine gestation. Free fluid is nonspecific and may present as anechoic or echogenic and in varying amounts. Simple free fluid and an empty uterus have a sensitivity of only 63% and a specificity of only 69%.18 However, hyperechoic fluid and/or large amounts of free fluid are more suggestive of an ectopic pregnancy.4, 20 There are no clear guidelines regarding if or when follow-up sonograms should be obtained. Follow-up examinations should be performed on an individual case basis, in coordination with patient's the clinical scenario and the beta-HCG levels. False Positives/NegativesFalse-positive ultrasonographic findings may be due to a missed abortion or an early normal intrauterine pregnancy (<4.5 wk), without or with secondary findings of an adnexal mass. The latter scenario may include an intrauterine pregnancy with a hemorrhagic corpus luteum cyst or an intrauterine pregnancy with an adnexal mass, as can be found with concurrent appendicitis. False-negative findings may be due to an intrauterine decidual reaction pseudosac that simulates an early intrauterine pregnancy. Approximately 8% of proven ectopic pregnancies are ultrasonographically normal on retrospective evaluation.2 A concomitant intrauterine pregnancy and ectopic pregnancy (particularly in infertility patients) are other causes of false-negative findings for ectopic pregnancy. As a note of caution, the limited far field of transvaginal ultrasonography can occasionally miss an ectopic pregnancy that is in a high position. Analysis of the patient's symptoms and placing a transducer on the area of maximal pain may aid the examination. The TA probe can help with this and provide a more global view of the pelvis and its contents. NUCLEAR MEDICINESection 8 of 12
FindingsNo clinically useful nuclear medicine studies have been identified for ectopic pregnancy. ANGIOGRAPHYSection 9 of 12
FindingsNo clinically useful angiographic findings of ectopic pregnancy have been identified. The associated ionizing radiation poses a hazard if a normal intrauterine pregnancy is present. INTERVENTIONSection 10 of 12
No current routine radiologic interventions are used for ectopic pregnancy. Along with serial beta-HCG evaluations, follow-up imaging is often performed for conservative and medical management. Case reports of rare interstitial ectopic pregnancies treated with interventional radiology-guided uterine artery embolization have been documented.21 A subsegment of patients may be undergoing a spontaneous resolution of an ectopic pregnancy at the time of diagnosis. These patients tend to have small, unruptured gestational sacs, very low beta-HCG levels, and no symptoms. Expectant management with close observation can be undertaken in an attempt to increase possible future tubal patency. The risk of expectant management is significant, and sequelae include tubal rupture and hemorrhage. These patients need to be carefully selected and followed up. Medical management The treatment of ectopic pregnancy with the administration of cell-growth inhibitors (methotrexate) is becoming increasingly common.22 This is largely the result of improved methods of detection and the diagnosis of early, unruptured ectopic pregnancies. Medical management is desirable because tubal patency may be preserved, therefore lowering the risk of a future ectopic pregnancy. Injections are typically given systemically, although a direct injection into the gestational sac under ultrasonographic guidance may be performed. Single and multidose regimens are now used with individual advantages and disadvantages.22, 23 With either regimen, though, patients must be closely followed up with serial beta-HCG determinations, and surgical intervention may still be necessary in some cases. Surgical management Surgical resection of the involved fallopian tube remains the definitive therapy. Laparoscopic salpingostomy is now being used as a more conservative surgical approach to potentially preserve the fallopian tube. Medical/Legal Pitfalls
Related Medscape topics: Special Concerns
Related Medscape topics: MULTIMEDIASection 11 of 12
REFERENCESSection 12 of 12
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