Cesarean scar defect: a prospective study on risk factors.

BACKGROUND: Cesarean scar defect (isthmocele) is a known complication after cesarean delivery. It has become more common due to a rising cesarean delivery rate. Isthmocele has been associated with various gynecological and obstetric problems such as uterine rupture, cesarean scar pregnancy, and bleeding disorders. OBJECTIVE: We sought to prospectively investigate factors associated with the risk for isthmocele assessed by sonohysterography. STUDY DESIGN: A prospective observational cohort study was conducted in 401 nonpregnant women who were recruited within 3 days of cesarean delivery. Women were evaluated with sonohysterography 6 months after cesarean delivery to detect a possible isthmocele. The ultrasonographer was blinded to any clinical information. The main outcome measure was the presence of isthmocele. Type of surgery (elective vs emergency), maternal background variables, and factors related to pregnancy, labor, and postoperative recovery were analyzed in relation to isthmocele. A logistic regression model was used to assess independent risk factors from univariate analysis. RESULTS: In all, 371 women were examined with sonohysterography resulting in a follow-up rate of 92.5%. The prevalence of isthmocele was 45.6%. Independent risk factors for isthmocele development were a history of gestational diabetes (odds ratio, 1.73; 95% confidence interval, 1.02-2.92; P = .042), previous cesarean delivery (odds ratio, 3.14; 95% confidence interval, 1.90-5.17; P < .001), and advanced maternal body mass index (odds ratio, 1.06; 95% confidence interval, 1.01-1.11; P = .012). Every additional unit of body mass index increased the risk of isthmocele by 6%. In the subgroup of emergency cesarean delivery, longer duration of active labor increased the risk for isthmocele (odds ratio, 1.06; 95% confidence interval, 1.01-1.11; P = .032). There was no statistically significant difference in prevalence between the groups of elective and emergency cesarean delivery (P = .898). CONCLUSION: Based on sonohysterographic examination, maternal body mass index, gestational diabetes, and previous cesarean deliveries are associated with an increased risk for incomplete healing of the uterine incision.