Incisional hernias (alternative plural: herniae) are relatively common and along with parastomal hernias, umbilical hernias, paraumbilical hernias, and Spigelian hernias, they are usually anterior abdominal hernias.
Incisional hernias usually develop within a few months of surgery, but a small proportion can remain clinically silent for years. They typically occur after laparotomy with rates of ~7.5%.
Numerous risk factors for developing an incisional hernia have been identified:
- preoperative factors: increasing age, female gender, BMI >25, increasing thickness of subcutaneous fat based on CT, preoperative chemotherapy
- intraoperative factors: midline incision, contaminated or infected wound noted during procedure, intraoperative blood loss
- postoperative factors: surgical site infection
Incisional hernias occur most frequently through previous laparotomy scars (other incisional hernias are possible, such as a lung hernia). Widening or dehiscence of the scar allows intra-abdominal contents to herniate into the subcutaneous tissues.