A<unk>  (also termed pilonidal<unk>  or spinal<unk>  is a small depression in the skin, located just above the buttocks. The name comes from the sacrum, the bone at the end of the spine, over which the<unk> s are found.<unk> s are rare, occurring in up to 4% of the population. The majority of these<unk> s are minor and do not represent any underlying disease; however, the minority may be a sign of disease, notably spina bifida. Even so, this is usually the spina bifida occulta form, which is the least serious kind. Additionally, a<unk>  may be indicative of a possible kidney problem that can be checked with an ultrasound.<unk> s are usually spotted in post-natal checks by a pediatrician, who will check: * whether the floor of the<unk>  can be seen to be covered with skin; * whether there is a tuft of hair in the<unk> ; * whether there are any other problems such as weak lower limbs; * the distance from the buttocks to the<unk>  (closer is better).
Sacral dimple
Naegele obliquity
Midline cervical cleft
Epispadias
Absence of gluteal muscle
Carpometacarpal bossing
Inverted nipple
Webbed penis