A hernia is a sac formed by the lining of the abdominal cavity (peritoneum). The sac comes through a hole or weak area in the strong layer of the belly wall that surrounds the muscle. This layer is called the fascia.

Which type of hernia you have depends on where it is:

• Femoral hernia is a bulge in the upper thigh, just below the groin. This type is more common in women than men.
• Hiatal hernia occurs in the upper part of the stomach. Part of the upper stomach pushes into the chest.
• Incisional hernia can occur through a scar if you have had abdominal surgery in the past.
• Inguinal hernia is a bulge in the groin. It is more common in men. It may go all the way down into the scrotum.
• Umbilical hernia appears as a bulge around the belly button. It occurs when the muscle around the belly button doesn't close completely.

Hernia - inguinal; Inguinal hernia; Direct and indirect hernia; Rupture; Strangulation; Incarceration

Usually, there is no obvious cause of a hernia. Sometimes hernias occur with heavy lifting, straining while using the toilet, or any activity that raises the pressure inside the belly area. Hernias may be present at birth, but the bulge may not be noticeable until later in life. Some patients may have a family history of hernias.

Babies and children can get hernias. It happens when there is weakness in the belly wall. About 5 out of 100 children have inguinal hernias. They are more common in boys. Some children may not have symptoms until they are adults.

Any activity or medical problem that increases pressure on the tissue in the belly wall and muscles may lead to a hernia, including:

• Chronic constipation and pushing hard (straining) to have a bowel movement
• Chronic cough
• Cystic fibrosis
• Enlarged prostate, straining to urinate
• Extra weight
• Fluid in the abdomen (ascites)
• Heavy lifting
• Peritoneal dialysis
• Poor nutrition
• Smoking
• Overexertion
• Undescended testicles

There are usually no symptoms. Some people have discomfort or pain. The discomfort may be worse when you stand, strain, or lift heavy objects. In time, most people will complain about a bump that is sore and growing. 

If a hernia gets bigger, it may get stuck inside the hole and lose its blood supply. This is called "strangulation."  If this occurs, you will need urgent surgery.

Your doctor or nurse can usually see or feel a hernia when they examine you. You may be asked to cough, bend, push, or lift. The hernia may get bigger when you do this.

The hernia (bulge) may not be easily seen in infants and children, except when the child is crying or coughing. 

 Ultrasound or CT scans may be done to look for a hernia.

If you may have a blockage in your bowel, you will need an x-ray of the abdomen.

The outcome for most hernias is usually good with treatment. It is rare for a hernia to come back. Incisional hernias are more likely to return.

In rare cases, inguinal hernia repair can damage structures involved in the function of a man's testicles.

Another risk of hernia surgery is nerve damage, which can lead to numbness in the groin area.

If a part of your bowel was trapped or strangulated before surgery, it may lead to a bowel perforation or dead bowel.

Call your doctor right away if:

• You have a painful hernia and the contents cannot be pushed back into the abdomen using gentle pressure
• You develop nausea, vomiting, or a fever along with a painful hernia
• You have a hernia that becomes red, purple, dark, or discolored

Call your doctor if:

• You have groin pain, swelling, or a bulge
• You have a bulge or swelling in the groin or belly button, or that is associated with a previous surgical cut.

• Use proper lifting techniques.
• Lose weight if you are overweight.
• Relieve or avoid constipation by eating plenty of fiber, drinking lots of fluid, going to the bathroom as soon as you have the urge, and exercising regularly.
• Men should see their health care provider if they strain with urination. This may be a symptom of an enlarged prostate.

Turnage RH, Badgwell B. Abdominal wall, umbilicus, peritoneum, mesenteries, omentum, and retroperitoneum. In: Townsend CM, ed. Sabiston Textbook of Surgery. 19th ed. Philadelphia, Pa: Saunders Elsevier;2012:chap 45.