Evaluation of preoperative ultrasound signs associated with bladder injury during complex Cesarean delivery: a case-control study.

OBJECTIVES: Intraoperative hemorraghe and peripartum hysterectomy are the main complications in patients presenting with a low-lying or placenta previa undergoing repeat cesarean delivery. Patients with a high probability of placenta accreta spectrum (PAS) at birth also have a higher risk of intraoperative urologic injuries and the aim of this study was to evaluate the ultrasound signs and intraoperative features associated with these injuries.

METHODS: This was a retrospective case-control study of consecutive singleton pregnancies included in a prospective cohort of patients with a history of at least one prior cesarean delivery (CD) and were diagnosed prenatally with an anterior low-lying or placenta previa at 32-36 weeks. All patients underwent investigational preoperative transabdominal and transvaginal ultrasound examinations within 48h prior to delivery. Ultrasound anomalies of uterine contour and utero-placental vascularity and gross anomalies of the lower uterine segment (LUS) and surrounding pelvic tissue at delivery were recorded using a standardised protocol including the evaluation of the size of anomalies of uterine contour. The diagnosis of PAS was established when one or more placental lobule(s) could not be digitally separated from the uterine wall at delivery or during the gross examination of the hysterectomy or partial myometrial resection specimens, confirmed by histopathology. Data were compared between cases complicated by intraoperative urologic injuries and three controls from the same cohort matched by parity and the number of prior cesarean deliveries using conditional logistic regression.

RESULTS: There were 16 (9.4%) patients with an intraoperative bladder injury out of a cohort of 170 patients managed by the same multidisciplinary team during the study period. There were no patients diagnosed with ureteric or bladder trigone damage. Fourteen patients (87.5%) with a bladder injury had histopathologic evidence of PAS at birth including 11 (68.8%) cases described on microscopic examination as placenta increta and three as placenta creta. There was a significant (p= 0.03) difference between cases and controls in the distribution of the intraoperative LUS vascularity with the higher the number of enlarged vessels the higher the odds ratio (OR) of bladder injury. The multivariable regression analysis revealed that both gestational age and LUS remodelling on transabdominal ultrasound were associated with a bladder injury. A longer gestational age was associated with a lower risk of an injury. A higher LUS remodelling grade on TAS was associated with an increased risk of bladder injury. Patients with a grade of 3 (involving > 50% of the LUS) had odds of a bladder injury that were 9 times higher than for patients with a grade of 1 (involving < 30% of the LUS).

CONCLUSIONS: Preoperative ultrasound examination is useful in the evaluation of the risk of the intraoperative bladder injury in patients with a history of prior CD presenting with a low-lying or placenta previa. The larger the remodelling of the LUS on transabdominal ultrasound the higher the risk of adverse urologic events. This article is protected by copyright. All rights reserved.