Biometric Sonographic Findings of Abnormally Adherent Trophoblastic Implantations on Cesarean Delivery Scars

Objectives The purpose of this study was to review first‐trimester transvaginal sonograms of patients with cervicoisthmic implantations and prior cesarean deliveries to determine whether sonographic biometric measurements can distinguish between abnormally adherent trophoblastic implantations and normally implanted pregnancies. Methods Our database was reviewed from October 2006 through December 2011 for patients with first‐trimester sonographic diagnoses of cervicoisthmic implantations and previous cesarean deliveries. Biometric measurements of the smallest distance from the anterior trophoblastic border to the uterine serosa were performed on transvaginal sagittal images of the uterus. Outcomes were classified into 5 categories: cesarean scar pregnancy, placental invasion (accreta/increta/percreta), previa without invasion, spontaneous abortion, and delivered intrauterine pregnancy. Statistical methods included analysis of variance with the Tukey range test and Student t test. Results Of 77 studies, outcome data were available for 56 patients. The mean gestational age was 8.8 weeks (minimum, 2.0 weeks; maximum, 14.9 weeks). The anterior trophoblastic border distances from the uterine serosa were significantly smaller in cesarean scar pregnancies (mean, 1.6 mm; SD, 0.6 mm) and placental invasion pregnancies (mean, 2.2 mm; SD, 1.0 mm) than the normally implanted groups (mean, 7.9 mm, SD, 3.3 mm; P < .0001). Conclusions Smaller trophoblastic border distances to the anterior uterine serosa are seen in abnormally adherent trophoblastic implantations, and these distances distinguish them from other pregnancy outcomes.