Cesarean scar defects: an underrecognized cause of abnormal uterine bleeding and other gynecologic complications.

The gynecologic sequelae due to deficient uterine scar healing after cesarean section are only recently being identified and described. These include conditions such as abnormal bleeding, pelvic pain, infertility, and cesarean scar ectopic pregnancy, as well as a potentially higher risk of complications and difficulties during gynecologic procedures such as uterine evacuation, hysterectomy, endometrial ablation, and insertion of an intrauterine device. The proposed mechanism of abnormal uterine bleeding is a pouch or "isthmocele" in the lower uterine segment that causes delayed menstrual bleeding. The prevalence of symptomatic or clinically relevant cesarean scar defects (CSDs) ranges from 19.4% to 88%. Possible risk factors for CSD include number of cesarean sections, uterine position, labor before cesarean section, and surgical technique used to close the uterine incision. There are no accepted guidelines for the diagnostic criteria of CSD. We propose that a CSD be defined on transvaginal ultrasound or saline infusion sonohysterography as a triangular hypoechoic defect in the myometrium at the site of the previous hysterotomy. We also propose a classification system to aid in standardized classification for future research. Surgical techniques for repair of CSD include laparoscopic excision, resectoscopic treatment, vaginal revision, and endometrial ablation.