A hernia is a defect, or hole, in layers of the abdominal or pelvic wall.  This can lead to protrusion of tissue – fat, bowel (intestines), other organs – through the defect.   Hernias can develop naturally from birth, over time from stress & strain of your abdominal and pelvic walls, from a traumatic injury, or from weakness following a prior surgery (incisional hernia).

The abdominal wall is a complex array of skin and soft tissue, muscle, fascia, and a thin lining called peritoneum, going from outside to inside.  Most hernias are defects in fascia, which forms layers of thick strong fibrous tissue that help contain our abdominal wall.  When tissue or organs push through the hernia defect it can stretch a space under the skin called the hernia sac.  When hernias expand, the hernia defect, hernia sac, or both can enlarge.

Symptoms

Some hernias don’t cause any symptoms at all, but many range from mild to severe symptoms depending on the size and location as well as what contents are protruding through it.  Common symptoms are bulging and pain, with varying severity of pain.   If bowels are involved with the hernia, you can develop gastrointestinal symptoms.

Reducible vs. incarcerated hernias

If hernia contents move in and out of the defect, but can be pushed back inside through the hole, or fall back in on its own, this is reducible.   If the contents stay stuck through the defect, this is incarcerated.

Incarcerated hernias aren’t always concerning, but they should be evaluated, as they can be dangerous if left unattended.

Concerning hernias

Incarcerated (stuck) hernias can lead to some potentially dangerous scenarios:

• Obstruction – this can occur when bowels are kinked or pinched off by the hernia defect or within the hernia sac, which blocks up the bowels and prevents the forward movement of digesting food.   This backup of digesting food, liquid, and gas can lead to nausea & vomiting, abdominal bloating and enlargement, and limited or no passage of bowel movements or gas. 
• Strangulation – this can occur when bowels (or other tissue) are stuck within the hernia defect or within the hernia sac, and the blood supply gets “squeezed out” of the bowels. This can cause the bowels or tissues to die, and you can become very sick.  
• **Symptoms when to seek emergency evaluation** - you could have some or all of these symptoms: 
  1. Firm or hard bulging at area of hernia
  2. Severe pain at area of bulging
  3. Redness or other new skin changes
  4. If obstructed, can also have nausea & vomiting, abdominal bloating and enlargement, and limited or no passage of bowel movements or gas. 

Types and locations of hernias

It's important to note that some hernias can fit into more than one type

Ventral hernias

• Ventral hernia – any hernia of the front of the abdominal wall
• Umbilical hernia – a common hernia that develops at or near the umbilicus (belly button)
• Epigastric hernia – another common hernia that develops in the upper abdomen above the umbilicus
• Incisional hernia – a defect in a weakened spot from a prior surgical incision
• Parastomal hernia – hernia that develops next to an ostomy (urostomy, colostomy, ileostomy)
• Flank hernia – on the sides of the abdomen

Groin hernias

• Inguinal hernia – a common group of defects located into the pelvis, groin, and scrotum or labia. 
• Femoral hernia – a type of groin hernia that can protrude into the lower groin and thigh.
• Obturator hernia – another type of pelvic/groin hernia that can protrude into the lower groin and thigh.

Hiatal / Paraesophageal hernias

Hiatal hernias are a different type of hernias compared to most others mentioned.  These involve defects near the esophagus and stomach where it passes through middle of the diaphragm which separates the chest from the abdomen.

Other hernias

• Spigelian hernia – defect near the lower middle side of the abdomen
• Diaphragmatic hernia – a defect in the diaphragm, a muscle which separates the chest from the abdomen.  Most commonly these are congenital (born with it), but they can develop from a traumatic injury. 
• Lumbar hernia – defect near the back side
• Pelvic hernia – a weakness in the deep pelvis, typically after prior pelvic surgery or from pelvic floor weakness