Ultrasound-Based Diagnosis of Interstitial Ectopic Pregnancy: Role of Morphological Features

This was a retrospective observational study utilizing data from a single-specialist early-pregnancy unit. We evaluated the diagnostic accuracy of transvaginal ultrasound (TVS) in various morphological presentations of interstitial ectopic pregnancy (IEP) among women who underwent surgery. Based on the presence or absence of a gestational sac (GS), IEP morphology was classified as GS type or inhomogeneous solid (IS) type. During the study period, 27 patients with IEP underwent surgical intervention. In those with the GS type, we observed a strong correlation between preoperative ultrasonographic findings and surgical observations; the positive predictive value of TVS diagnosis for GS-type IEP was 100%. In contrast, it was 45.5% for IS-type IEP, which presents unique diagnostic challenges due to its complex ultrasonographic appearance. Additionally, we assessed the ultrasound characteristics of IS-type IEP and discussed its differential diagnosis.