A uterine niche is a reservoir-like pouch in the anterior uterine isthmus located at the site of a previous CS scar. First published and describe din 1961, there have been a variety of publications looking at "best practice" at cesarean hysterotomy closure to try to minimize its occurrence. This defect has been linked to abnormal placentation in subsequent pregnancies, CS scar ectopic pregnancies, abnormal uterine bleeding, and dysmenorrhea. While the complete pathogenesis of the niche defect is not completely understood, hysterotomy closure techniques have been implicated in its formation. Should we include the endometrial decidual layer at hysterotomy closure or should we exclude it. Its a debated subject but the data does favor one approach over the other. In this episode, we will examine that data.