Objective: To explore the clinical value of ultrasonography for early detection and monitoring of angular pregnancy during the first-trimester.

Methods: For this retrospective study, we enrolled 23 patients with asymptomatic angular pregnancy who were diagnosed by ultrasound at early pregnancy and who underwent ultrasound follow-up to determine its clinical outcome. An ultrasound unit E8 (GE Healthcare, Milwaukee, WI) associated with a 5-9 MHz convex array transvaginal probe was used to image the gestational sac by both two-dimensional and three-dimensional modes. Transvaginal sonographic observation included the location, size, and shape of the gestational sac, as well as the relationship between the gestational sac and the endometrium. When the gestational sac was located close to or at the corners of the uterus, the wall thickness of the corner was measured and documented for follow-up during the first-trimester.

Results: Angular pregnancy (n=23) was detected by first ultrasonography at 37-50 days of gestation. All patients then underwent dynamic sonographic monitoring and were closely followed every 5-10 days for 1-3 weeks. In 3 cases, ultrasound showed embryo demise at follow-up examination. Seven cases were converted to intrauterine pregnancies based on sonographic findings and carried to term. In 13 cases, ultrasonography showed the gestational sacs grew outward in the corner of the uterus where the wall was thinning and had asymmetrical corners. Based on the ultrasound results, thesepregnancies were terminated (by surgery [n=6] or medication [n=7]).

Conclusions: Sonography is a valuable clinical tool for early detection and monitoring of angular pregnancy. Follow-up ultrasound can provide useful information for observing the transformation of angular pregnancy to guide clinical management, including whether to continue or terminate pregnancy.