Understanding Hernias: the Basics

Medically Reviewed by Sabrina Felson, MD on December 23, 2022

What Is a Hernia?

A hernia happens when an organ or fatty tissue squeezes through a weak spot in a surrounding muscle or connective tissue called fascia. They often occur where the abdominal wall is weaker, such as in the abdomen (belly area) or groin, and can have various causes. 

Hernias can be painful. In some cases, they need emergency treatment. Call 911 right away if:

  • Your hernia is extremely painful, growing quickly, swollen, or red.
  • You vomit or feel nauseous.
  • You have constipation or bloating.
  • You have a fever.

In a reducible hernia, the lump can be pushed back through the abdominal wall. If not, it's an irreducible hernia, which is more likely to have serious complications.

A hernia is an emergency if it is “incarcerated.” In an incarcerated hernia, tissue (such as from the bowel) has slipped through the hernia and gotten stuck there. Stool may not be able to get through normally, which can cause pain, nausea, vomiting, and even tear the bowel wall. If an incarcerated hernia becomes “strangulated,” the bowel tissue has started to die and needs emergency surgery. 


Hernia Causes

Ultimately, all hernias are caused by a combination of pressure and an opening or weakness of muscle or fascia. The pressure pushes an organ or tissue through the opening or weak spot. Sometimes the muscle weakness is present at birth. But more often, it happens later in life.

Anything that causes an increase in pressure in the abdomen can cause a hernia, including:

  • Lifting heavy objects without stabilizing the abdominal muscles
  • Diarrhea or constipation
  • Persistent coughing or sneezing

In addition, obesity, poor nutrition, and smoking can weaken muscles and make hernias more likely.

Types of Hernias

The most common types of hernia are inguinal (inner groin), incisional (resulting from a surgical cut, or incision), femoral (outer groin), umbilical (belly button), and hiatal (upper stomach).

Groin hernias

About 3 out of every 4 hernias are in the groin. There are two types: inguinal and femoral.

Almost all groin hernias are inguinal. You get them when part of your intestine pushes through a weakness in the lower belly and affects an area of the groin called the inguinal canal.

There are two kinds of this hernia:

  • Indirect. The more common type; it enters the inguinal canal.
  • Direct. It does not enter the inguinal canal but goes straight through the bowell wall.

They’re much more common in men than women, but they’re not limited to adults. 

With an inguinal hernia, you’ll probably see a lump where your thigh and groin come together. It may seem to go away when lying down, but you see it clearly when you cough, stand, or strain. 

Generally, these hernias aren’t dangerous. Your doctor may consider watchful waiting, or monitoring the hernia. 

Femoral hernias account for only a few out of every 100. They’re more common in older women. They are often mistaken for inguinal hernias.

Femoral hernias bulge into a different area of the groin called the femoral canal. You might see a lump right around the crease of the groin or just into the upper thigh.Your doctor will likely recommend that you get surgery for a femoral hernia instead of watchful waiting, since they are more likely to get stuck without being reducible.

Umbilical hernias

This is the second most common type of hernia. Umbilical hernias happen when fat or part of the intestine pushes through muscle near the belly button. They’re more common in newborns, especially in those born earlier than expected and babies under 6 months old. But adults can get them, too.

Women are more likely than men to get an umbilical hernia. Your chances are also higher if you:

  • Are overweight
  • Have been pregnant more than once
  • Have a lot of belly fluid (a condition called ascites)
  • Have a long-term cough
  • Have trouble peeing because of an enlarged prostate
  • Are constipated for long periods of time
  • Vomit repeatedly

What all of these risk factors have in common is increased pressure in the abdomen that pushes the hernia out.

Incisional hernias

If you have surgery in which a doctor makes an opening through your belly, you might get an incisional hernia later. Tissue can poke through where the skin has been weakened by a scar left after surgery. Like groin hernias, they can lead to more serious problems if they’re not repaired. 

Incisional hernias are common in people who have had an operation, especially emergency surgery. You can be more likely to get one if you do any of these things before your incision heals completely:

  • Gain a lot of weight
  • Exercise too soon or too heavily
  • Get pregnant

Your chances are also higher if the wound gets infected or if you:

  • Are a man over 60
  • Are obese
  • Have long-term lung disease
  • Have diabetes or kidney failure
  • Smoke
  • Take long-term medications like steroids or drugs that affect your immune system

These are a little different from the other types of hernias because of where they happen. 

Hiatal hernias involve your diaphragm, the sheet of muscle that separates your chest from your belly. Your esophagus runs from your throat to your stomach and passes through an opening in the diaphragm.

With a hiatal hernia, part of the stomach bulges up through this opening and into the chest. You won’t see any lump, but you might get heartburn or chest pain and notice a sour taste in your mouth.

Although they’re the most common hernias seen in pregnant women, this type of hernia is most often found in people over age 50.

Other types of hernias

Less common types of hernias include:

  • Epigastric hernia. This is when fat pushes through the belly somewhere between the belly button and lower part of the breastbone. These show up in men more often than women.
  • Giant abdominal wall hernia. You might get one of these if you have an incisional hernia or some other kind that’s hard to treat and keeps coming back. 
  • Spigelian hernia. You get this type when fat tissue pushes through muscle below your belly button along the bottom edge of where your six-pack might be.

Show Sources


National Institute of Diabetes and Digestive and Kidney Disorders.

National Library of Medicine.

Better Health Channel of Australia’s Victoria State Government: “Hernias.”

Mayo Clinic: “Saving Lives With Gus: Incarcerated Hernia.”

Johns Hopkins: “Comprehensive Hernia Center.”

NHS: “Umbilical Hernia Repair,” “Hernia,” “Femoral Hernia Repair,” “Inguinal Hernia Repair,” “Hiatus Hernia.”

Cleveland Clinic: “Hernia,” “Hiatal Hernia.”

KidsHealth: “Hernias.”

The British Hernia Center: “Hernia Overview.”

Medscape: “Hernia Reduction.”

Mount Sinai Beth Israel, Hernia Center: “Hernia Types.”

Dartmouth Hitchcock, Hernia Surgery Center: “Types of Hernias.”

Mayo Clinic: “Inguinal Hernia.,” “Umbilical Hernia.”

Johns Hopkins Medicine, Comprehensive Hernia Center: “Conditions We Treat: Hiatal Hernia,”  “Umbilical Hernia,” “Incisional Hernia,” “Could I have a hernia?”

Royal United Hospital Bath: “Spigelian Hernia Repair.” “Indirect inguinal hernia,” “Direct inguinal hernia.”

National Center for Biotechnology Information: “Incisional Hernia.”

Sudan Medical Monitor: “Incisional hernia: Risk factors, incidence, pathogenesis, prevention and complications.”

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