What is Hernia Surgery ?. A hernia is a weakness or defect in the abdominal wall. It may be present from birth or develop over a period of time. If the defect is large enough, abdominal contents such as the bowels may protrude through the defect causing a lump or bulge felt by the patient. Hernias develop at certain sites that have a natural tendency to be weak: the groin, umbilicus (belly button) and previous surgical incisions. Meet The Best Hernia Surgeon in Pune (Dr Gowri Singh).