Hourglass cesarean scar: A neglected external niche in association with the internal niche.

Suboptimal uterine wound healing and intracavitary niche formation after cesarean section can lead to clinical complaints in the future, such as dyspareunia, dysmenorrhea, chronic pelvic pain, abnormal uterine bleeding, and even subfertility [1]. In the existing literature, cesarean scar defect is referred to by a number of different terms: niche, diverticulum, isthmocele, isthmic trans mural hernia, and cesarean scar pouch [1-4].