Newborns have a small eye behind the buttocks, can be considered to be anal fistula, occult spina bifida and other causes, can be based on the specific performance or through the examination way to determine. 1. anal fistula: some children are affected by genetic, infection and other factors, there is a small eye above the buttocks, medical also known as anal fistula, superficial skin breakage will form a typical anal fistula, there will be some secretion, but also have pain, mainly to surgical treatment. 2. Hidden spina bifida: this is a manifestation of spinal canal defects, in the absence of symptoms can be left untreated, the onset of symptoms of lower limb weakness, mild muscle atrophy, numbness, enuresis, sometimes manifested as lumbago or leg pain. Newborns with small eyes behind the buttocks, it is recommended to take the newborn to the hospital for examination, to determine the cause of the case, timely treatment, to avoid other adverse effects.