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Key Terms

  1. Ectopic pregnancy: a gestational sac located outside of the uterine lumen. The most common location is within the ampullary segment of the fallopian tube (tubal); other locations include: interstitial, cornual, cervical, within a C-section scar (“scar ectopic”), intra-abdominal, or intraovarian.

  2. Pregnancy of “unknown location”: pregnancy whose location (intra- or extrauterine) cannot be determined sonographically. Short interval (3-5 day) follow-up sonography is highly recommended.

  3. Concept of “discriminatory zone”: β-hCG value above which evidence of an early intrauterine pregnancy should always or reliably be seen on transvaginal sonography. This concept, previously thought to be of major diagnostic value, has now been shown to be of limited value.

  4. Doubling time: expected time interval when the β-hCG level doubles in a normal early intrauterine pregnancy. Typically, the expected normal increase of hCG is greater than or equal to 50% in 48 hours. It should be noted, however, that there is a fairly large range of normal, physiologic values.


Recent improvements in the sonographic depiction of uterine and adnexal structures with transvaginal sonography (TVS) in 2D, 3D, and color Doppler ultrasound and refinements and better understanding of quantitative human chorionic gonadotropin (hCG) have enhanced the ability to identify whether an early pregnancy is intra- or extrauterine. In the clinical setting, as many as 30% of women present with pain and/or bleeding in early pregnancy. These two findings raise the suspicion for early pregnancy failure (EPF). Up to 25% of recognized pregnancies end in miscarriage, and 1% to 2% of these will ultimately be diagnosed as ectopic gestations. Although the sonographic findings in early pregnancy can be subtle, a diagnosis of EPF and ectopic pregnancy is possible in most cases when sonographic findings are combined with results of serial hCG assays. In the case of ectopic pregnancy, early diagnosis affords the patient more conservative medical or surgical options and decreases the risk for rupture, which often leads to more radical, emergent surgery.

Despite advances in the diagnostic tests used in early pregnancy, ectopic pregnancy accounts for an estimated 6% of all pregnancy-related deaths from 1991 to 1999 in the United States.1 A high index of suspicion is required when evaluating women who present with lower abdominal pain and amenorrhea, as reflected by the fact that the diagnosis is overlooked by the initial examining physician in up to 70% of cases.2 Expeditious and accurate diagnosis of patients who are suspected of having ectopic pregnancy is important so that timely intervention and proper management can be instituted. If it is recognized early, before tubal rupture, it may be possible to surgically remove the gestational sac by linear salpingostomy or treat with methotrexate therapy, thereby preserving the tube and future chances of achieving pregnancy. Advanced ectopic pregnancies can result in significant damage to tubal architecture, which often leads to salpingectomy. If the remaining tube is compromised, fertility can be significantly decreased as a ...

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