Niche, a growing problem for gynecologist and obstetrician.

Niche formation is a growing problem in Brazil and worldwide. Today, cesarean delivery rates far exceed levels recommended by the World Health Organization. The procedure constitutes the most common surgery in the world, and its most frequent complication is niche formation (84% prevalence), as detected by sonohysterography. Several gynecological problems related to this cesarean scar defect can ensue, with the most frequent symptom being abnormal uterine bleeding. Obstetric problems in subsequent pregnancies include uterine rupture, abnormal placentation, and cesarean scar pregnancy. Recommended treatments yield good results, but there is no consensus on niche prevention, owing to an incomplete understanding of its pathophysiology. Comparisons of surgical techniques have revealed no significant differences. Further studies are needed to elucidate the multifactorial pathophysiology of niche and help to develop approaches for preventing its occurrence.