Abdominal hernias are classified as either abdominal wall or groin hernias. Strangulated hernias are ischemic from physical constriction of their blood supply. Strangulation can result in bowel infarction, perforation, and peritonitis.
ABDOMINAL WALL HERNIAS
Umbilical hernias: (protrusions through the umbilical ring) are mostly congenital, but some are acquired in adulthood secondary to obesity, ascites, pregnancy, or chronic peritoneal dialysis.
Epigastric hernias: occur through the linea alba.
Spigelian hernias: occur through defects in the transversus abdominis muscle lateral to the rectus sheath, usually below the level of the umbilicus.
Incisional hernias: occur through an incision from previous abdominal surgery.
Inguinal hernias: occur above the inguinal ligament. Indirect inguinal hernias traverse the internal inguinal ring into the inguinal canal, and direct inguinal hernias extend directly forward and do not pass through the inguinal canal.
Femoral hernias: occur below the inguinal ligament and go into the femoral canal. About 75% of all abdominal hernias are inguinal. Incisional hernias comprise another 10 to 15%. Femoral and unusual hernias account for the remaining 10 to 15%.
SYMPTOMS AND SIGNS
Most patients complain only of a visible bulge, which may cause vague discomfort or be asymptomatic. Most hernias, even large ones, can be manually reduced with persistent gentle pressure; placing the patient in the Trendelenburg position may help. An incarcerated hernia cannot be reduced and can be the cause of a bowel obstruction. A strangulated hernia causes steady, gradually increasing pain, typically with nausea and vomiting. The hernia itself is tender, and the overlying skin may be erythematous; peritonitis may develop depending on location, with diffuse tenderness, guarding, and rebound.