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E1724. Ultrasound Evaluation of Ectopic Pregnancy: Hiding Places, Lookalikes, and Other Common Pitfalls
Authors
  1. Mihan Lee; New York Presbyterian Hospital; Weill Cornell Medical Center
  2. Preethi Guniganti; New York Presbyterian Hospital; Weill Cornell Medical Center
Background
Ectopic pregnancy is the most common cause of death during the first trimester of pregnancy, and accounts for up to 3% of all maternal mortality. For survivors of the condition, additional morbidity comes in the form of impaired future fertility. Recent estimates suggest that ectopic pregnancy is increasing in overall prevalence in recent decades, and currently accounts for up to 2% of all pregnancies. Early diagnosis of ectopic pregnancy is therefore critical to minimize maternal morbidity and mortality. The most common presenting symptoms of ectopic pregnancy are pelvic pain and vaginal spotting. For a patient presenting with these symptoms, in the setting of a last menstrual period 5-9 weeks prior, initial evaluation should be with a bHCG level; if this returns positive, pelvic ultrasound is warranted for further evaluation. The ampulla of the Fallopian tube is the most common location for an ectopic pregnancy, accounting for nearly 70% of cases; on ultrasound, this is seen as an adnexal mass separate from the ovary, with a hyperechoic, hypervascular ring surrounding an extrauterine gestational sac. However, ectopic pregnancy can occur in other locations including the cervix, the ovary, a Cesarean scar, the myometrium, and the peritoneal cavity.

Educational Goals / Teaching Points
This educational exhibit will review ultrasound appearances of ectopic pregnancy, with an emphasis on its less common presentations. Using a case-based approach, it will illustrate several potential reasons that ectopic pregnancy can be missed on ultrasound evaluation, along with strategies for avoiding these pitfalls.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
Cases to be presented will be divided into two categories. The first will present errors of search pattern, in which the ectopic pregnancy was missed due to inadequate visualization of a relevant structure or early termination of search; these include inadequate visualization of the cervix, failure to pan the adnexa, and early termination of search in the setting of a visualized intrauterine pregnancy. The second category will describe errors of misattribution, in which the ectopic pregnancy was visualized but incorrectly characterized as a different condition (often one that more commonly occurs at that location, including fibroids, angular pregnancies, abortions in progress, and a corpus luteum). Each case will be accompanied by strategies and tips for avoiding similar misses in the viewer’s own practice, with tips regarding optimal search pattern, useful ultrasound maneuvers, and key imaging features for distinguishing ectopic pregnancy from its lookalike condition.

Conclusion
Early and accurate detection of ectopic pregnancy is critical to minimizing the maternal morbidity and mortality associated with this common condition. This exhibit seeks to help diagnostic radiologists improve their sensitivity for ectopic pregnancy on ultrasound, especially those that occur in uncommon locations with uncommon presentations.