Hernias by themselves usually are harmless, but nearly all have a potential risk of having their blood supply cut off (becoming strangulated). If the hernia sac contents have their blood supply cut off at the hernia opening in the abdominal wall, it becomes a medical and surgical emergency.
Different types of abdominal wall hernias include the following:
- Inguinal hernia: Making up 75% of all abdominal wall hernias and occurring up to 25 times more often in men than women, these hernias are divided into 2 different types, direct and indirect. Both occur in the area of where the skin crease at the top of the thigh joins the torso (the inguinal crease), but they have slightly different origins. Both of these types of hernias can similarly appear as a bulge in the inguinal crease. Distinguishing between the direct and indirect hernia, however, is not that important because both are treated the same.
- Indirect inguinal hernia: An indirect hernia follows the pathway that the testicles made during prebirth development. It descends from the abdomen into the scrotum. This pathway normally closes before birth but remains a possible place for a hernia. Sometimes the hernial sac may protrude into the scrotum. An indirect inguinal hernia may occur at any age but becomes more common as people age.
- Direct inguinal hernia: The direct inguinal hernia occurs slightly to the inside of the site of the indirect hernia, in a place where the abdominal wall is naturally slightly thinner. It rarely will protrude into the scrotum. Unlike the indirect hernia, which can occur at any age, the direct hernia almost always occurs in the middle-aged and elderly because their abdominal walls weaken as they age.
- Femoral hernia: The femoral canal is the way that the femoral artery, vein, and nerve leave the abdominal cavity to enter the thigh. Although normally a tight space, sometimes it becomes large enough to allow abdominal contents (usually intestine) into the canal. A femoral hernia causes a bulge below the inguinal crease in roughly the middle of the thigh. Rare and usually occurring in women, femoral hernias are particularly at risk of becoming irreducible and strangulated.
- Umbilical hernia: These common hernias (10-30%) are often noted at birth as a protrusion at the bellybutton (the umbilicus). This is caused when an opening in the abdominal wall, which normally closes before birth, doesn’t close completely. If small (less than three quarters of an inch) this type of hernia usually closes gradually by age 2. Larger hernias and those that do not close by themselves usually require surgery at age 2-4 years. Even if the area is closed at birth, umbilical hernias can appear later in life because this spot remains a weaker place in the abdominal wall. Umbilical hernias most often appear later in elderly people and middle-aged women who have had children.
- Incisional hernia: Abdominal surgery causes a flaw in the abdominal wall that must heal on its own. This flaw can create an area of weakness where a hernia may develop. This occurs after 2-10% of all abdominal surgeries, although some people are more at risk. After surgical repair, incisional hernias have a high rate of returning (20-45%).
- Spigelian hernia: This rare hernia occurs along the edge of the rectus abdominus muscle, which is several inches to the side of the middle of the abdomen.
- Obturator hernia: This extremely rare abdominal hernia happens mostly in women. This hernia protrudes from the pelvic cavity through an opening in your pelvic bone (obturator foramen). This will not show any bulge but can act like a bowel obstruction and cause nausea and vomiting.
- Epigastric hernia: Occurring between the navel and the lower part of the rib cage in the midline of the abdomen, epigastric hernias are composed usually of fatty tissue and rarely contain intestine. Formed in an area of relative weakness of the abdominal wall, these hernias are often painless and unable to be pushed back into the abdomen when first discovered.