[Cesarean scare niche: Definition, diagnosis, risk factors, prevention, symptoms, adverse effects, and treatments]

To review the definitions, diagnostic methods, risk factors, symptoms, and treatments for caesarean scar niche.

Review of the literature, critical reflection, and pragmatic advice.

There is no consensus on the definition of caesarean scar niche. Some suggest an indentation≥2mm of the myometrium of the caesarean scar, but this is present in more than half of women with caesarean history and takes no account of woman's symptoms. The most popular diagnostic method is ultrasound±hysterosonography. Risks factors for niche are multiple Caesareans, Cesarean during labor with too low incision, and retroverted uterus. Symptoms include abnormal gynaecologic bleeding and pelvic pain, and their presence establish the "Caesarean scar syndrome". The risks of pregnancy with niche is poorly studied, but pregnancy is not contraindicated, even if the niche is untreated. The treatment of caesarean scar niche is mainly surgery and conservative. The former should be reserved for symptomatic patients, and those with secondary infertility and fertility treatment failure. Patients with residual myometrium thickness≥2.5mm may benefit from first-line hysteroscopic treatment, whereas a laparoscopic or vaginal approach could be offered in other cases.

A pragmatic definition of caesarean scar niche as a disease including symptoms is the necessary prerequisite for the management of women. The treatment is mainly surgical, or conservative depending on the desire for subsequent pregnancy.