Nipple flap is usually caused by inverted nipple, cracked nipple and other conditions. 1. Nipple inversion: nipple inversion is a kind of abnormal nipple development symptom, usually due to the patient’s presence of nipple smooth muscle dysplasia, shortening of breast ducts, etc. Some patients may be caused by inflammation of the nipple area in the late stage. This disease often leads to nipple splitting phenomenon, some patients due to excessive accumulation of local oil, dirt, but also cause nipple eczema, infection and so on. 2. Cracked nipples: this disease is common in breastfeeding women, mainly due to improper breastfeeding, resulting in nipples being bitten by babies. Most patients will have small cracks on the surface of the nipple, and some patients may have horizontal or vertical cracks on the nipple, resulting in nipple splitting. At the same time, the patient usually accompanied by nipple dryness, bleeding, pain and other symptoms, and in severe cases, the nipple area ulcers, blisters and so on. In addition, nipple inflammation, nipple swelling and other causes may also lead to nipple splitting, patients with nipple splitting are recommended to consult a doctor for examination, to clarify the specific cause of the disease and then actively treat it, so as to avoid inducing mastitis, breast abscess and other complications.