Background: Caesarean section (CS) scar niche is a well recognised complication of caesarean delivery and is defined as an indentation at the site of the CS scar with a depth of at least 2mm. Objectives: To review systematically the medical literature regarding the current diagnosis and management of uterine niche Materials and Methods: We carried out a systematic review using MeSH terms ‘niche’ OR ‘sacculation’ OR ‘caesarean scar defect’ OR ‘caesarean section scar’ OR ‘uterine defect’ OR ‘isthmocele.’ Articles included were peer-reviewed and in English language. Main Outcome Measures: Prevalence, symptoms, diagnosis, pathophysiology and management of uterine niche. Results: CS scar niche is common and, in a subgroup, produces a range of symptoms including post-menstrual bleeding, dyspareunia and subfertility. It may be linked to use of locked sutures during CS closure. Niche repair can be achieved laparoscopically or hysteroscopically and appears to improve symptoms, although solid conclusions regarding fertility outcomes cannot be drawn. Conclusions: CS scar niche is associated with a range of symptoms. Repair may aid subfertile patients and those with post-menstrual spotting. The presence of a niche is probably irrelevant in the absence of symptoms. What is New? LNG-IUS and surgical repair appear to improve symptoms in those with a niche.