A pilonidal sinus is a small hole or tunnel in the skin at the top of the buttocks, where they divide (the natal cleft). Most people with a pilonidal sinus don’t notice it until it becomes infected and causes symptoms.

A hernia occurs when there is a weakness in the layers of the abdominal wall and abdominal contents (such as part of the intestines) protrude through this weakness. Learn how Intus treates hernias.