E2139. Predictive Imaging Features of Uterine Dehiscence in the Second and Third Trimesters of Pregnancy
  1. Hassan Aboughalia; University of Washington Medical Center
  2. Margarita Revzin; Yale School of Medicine
  3. Douglas Katz; NYU Winthrop Hospital
  4. Mariam Moshiri; University of Washington Medical Center
Our study investigates the imaging features that can assist in predicting uterine dehiscence in pregnancy.

Materials and Methods:
Our imaging database was searched for keywords 'dehiscence, isthmocele, scar, defect' in exams performed from Jan 2000 to Dec 2018. 24 subjects matched our criteria. Excluding patients with no pre-delivery imaging and/or surgical records, 11 subjects were eligible for this study. Imaging was reviewed by an abdominal radiologist with 16 years of experience in obstetric imaging and a radiology fellow. A consensus agreement was used. The gravid uterus was evaluated for thickness at the LUS and the normal uterine thickness. In addition, the ratio between thinned and normal myometrium was generated. Medical records were searched for a history of prior cesarean section and neonatal outcome. Finally, the surgical findings were reviewed for correlation with imaging.

All subjects had a history of prior CS. 2nd-trimester ultrasound (US) showed a thin myometrium of 1.8-3 mm with a ratio of 33-50% between thinned and normal myometrium. This ratio decreased by 10-25% in the same trimester follow-up US. 3 patients had additional MRI in that trimester. Myometrial thickness at the dehiscence site ranged from 1.3-1.7 mm with a 24-26 % ratio. Thinned myometrium measured >1-2.6 mm in the 3rd trimester US with a ratio of 17-50%. Follow-up US showed an interval 0.5-1 mm increased thinning over time, with a 15-17% decrease in the ratio of the thinned to normal myometrium. Only 2 patients had MRI during the 3rd trimester which showed <1-1.8 mm myometrial thickness at the site of dehiscence with a ratio of thinned to normal myometrium of 16-33%. A single newborn was admitted to the NICU for 48 hours and was subsequently discharged in good condition. The operative note for all subjects agreed with the imaging finding of cesarean scar dehiscence. The transvaginal US remains the modality of choice to assess cesarean scar dehiscence. Thickness >3 mm excludes uterine dehiscence. MRI can be used to evaluate equivocal cases: however, our study did not have enough subjects to evaluate its role in this context.

This study highlights imaging role in evaluating cesarean scar dehiscence, a serious complication of the cesarean scar with possible catastrophic morbidity. It validates the role of transvaginal US in this context, which is crucial for delivery planning and to avoid the more ominous complication, uterine rupture.