Peritonitis is the inflammation of the peritoneum, a thin membrane that lines the abdominal cavity and covers the organs inside it. This condition is usually caused by an infection, rupture, or severe inflammation of one of the abdominal organs, such as appendicitis or pancreatitis.

The most common symptoms of peritonitis include abdominal pain and tenderness, fever, vomiting, and constipation. Because peritonitis can be life-threatening, it’s important to go to the hospital right away if peritonitis or any other serious abdominal condition is suspected.

Treatment for peritonitis is managed by a gastroenterologist and depends on the underlying cause. It usually involves antibiotics and hospitalization, and in some cases, surgery may also be needed.

Main symptoms

The main symptoms of peritonitis include:

Abdominal pain and tenderness;
Swelling of the abdomen;
Fever;
Nausea and vomiting;
Loss of appetite;
Sudden diarrhea or constipation;
Decreased urine output;
Excessive gas.

Pain caused by peritonitis tends to worsen with movement or when pressure is applied to the abdomen.

Confirming a diagnosis

Peritonitis is typically diagnosed by a doctor after an evaluation of symptoms and a physical exam, including asking the person to assume certain positions to assess the pain.

To identify the cause, the doctor may also order blood tests to check for signs of infection or inflammation, as well as imaging tests such as X-rays, ultrasound, or CT scans.

Possible causes

Peritonitis is usually caused by an infection, rupture, or severe inflammation of one of the abdominal organs. The most common causes include:

1. Appendicitis

Appendicitis is one of the most common causes of peritonitis. When the appendix becomes inflamed and is not treated quickly, the infection can spread through the abdominal cavity and reach the peritoneum. Complications such as rupture or abscess formation increase the risk of peritonitis.

2. Gallbladder inflammation

Also known as cholecystitis, this condition usually occurs when a gallstone blocks the bile duct, causing inflammation of the gallbladder. It must be treated promptly by a doctor, typically with surgery and antibiotics.

If left untreated, the inflammation can spread to nearby organs and the peritoneum, leading to peritonitis and complications such as abscess formation, fistulas, or sepsis.

3. Pancreatitis

Pancreatitis is inflammation of the pancreas that causes symptoms such as abdominal pain radiating to the back, nausea, and vomiting. When not properly treated, it can become severe and lead to complications such as peritonitis, necrosis, or abscess formation, which can be life-threatening.

4. Abdominal injuries

Injuries to abdominal organs caused by trauma, ruptures, inflammation, or surgical complications are important causes of peritonitis. These injuries can release irritating substances into the abdominal cavity or allow bacterial contamination, both of which can trigger peritoneal inflammation.

5. Medical procedures

Some medical procedures, such as peritoneal dialysis, gastrointestinal surgeries, colonoscopies, or endoscopies, can cause peritonitis due to complications like perforation or contamination of surgical instruments.

6. Paralytic ileus

Paralytic ileus is a condition where the intestines stop moving and normal peristalsis ceases. It can occur after abdominal surgery or result from inflammation, internal bleeding, or side effects of certain medications.

Symptoms of paralytic ileus include loss of appetite, constipation, vomiting, and bowel obstruction. In more severe cases, it can lead to bowel perforation, allowing bacteria to spread and cause peritonitis.

7. Diverticulitis

Diverticulitis occurs when small pouches (diverticula) that form in the intestinal wall become inflamed or infected, most often in the last section of the colon. It causes pain and tenderness in the lower left abdomen, as well as diarrhea or constipation, nausea, vomiting, fever, and chills.

Treatment for diverticulitis should begin promptly with antibiotics, pain relievers, dietary adjustments, and adequate hydration. This helps prevent the inflammation from worsening and reduces the risk of complications such as bleeding, fistulas, abscess formation, bowel obstruction, or peritonitis.

Treatment options

Treatment for peritonitis depends on the underlying cause, but medical care is always required as soon as possible in order to prevent serious complications.

Treatment generally involves antibiotics to treat the infection and stop the spread of bacteria. Hospitalization is usually required for intravenous (IV) fluids, pain medication, anti-inflammatory drugs, and sometimes oxygen therapy.

If these measures are not enough to control the condition, surgery may be necessary to treat the source of inflammation, such as removing the appendix, excising necrotic tissue, or draining an abscess.

Peritonitis: Symptoms, Causes & Treatment