Assessment of Cesarean hysterotomy scar before pregnancy and at 11-14 weeks of gestation: a prospective cohort study.

OBJECTIVE: To compare the appearance and measurement of Cesarean hysterotomy scar before pregnancy and at 11-14 weeks in a subsequent pregnancy.

METHODS: This was a prospective cohort study of women aged 18-35 years who had one previous Cesarean delivery (CD) at ≥ 37 weeks. Women were examined with saline contrast sonohysterography 6-9 months after CD. A scar defect was defined as large if scar thickness was ≤ 2.5 mm. Women were followed up and those who became pregnant were examined by transvaginal ultrasound at 11-14 weeks. Scar thickness was measured and scars were classified subjectively as a scar with or without a large defect. A receiver-operating characteristics curve was constructed to determine the best cut-off value for scar thickness to define a large scar defect at the 11-14-week scan.

RESULTS: A total of 111 women with a previous CD were scanned in the non-pregnant state and at 11-14 weeks in a subsequent pregnancy. The best cut-off value for scar thickness to define a large scar defect at 11-14 weeks was 2.85 mm, which had 90% sensitivity (18/20), 97% specificity (88/91) and 95% accuracy (106/111). In the non-pregnant state, large scar defects were found in 18 (16%) women and all were confirmed at the 11-14-week scan. In addition, a large defect was found in three women at 11-14 weeks that was not identified in the non-pregnant state.

CONCLUSION: The appearance of the Cesarean hysterotomy scar was similar in the non-pregnant state and at 11-14 weeks in a subsequent pregnancy. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.