Peritonitis is inflammation in your peritoneum, the tissue that lines the inside of your abdominal cavity. It’s usually caused by an infection, and sometimes by irritating bodily fluids. Infection in your peritoneum is especially dangerous because it can affect your abdominal organs. It can also transfer to your bloodstream and cause sepsis.
Your peritoneum is a thin membrane that lines the inside of your belly (abdomen) and wraps around the organs inside. Peritonitis is the term for inflammation of the peritoneum. The tissues can become inflamed if they’re exposed to irritating or infected body fluids. This usually happens when something inside leaks or breaks. Infection is the most common cause of peritonitis, and it can be very dangerous.
Your symptoms may vary depending on the type of peritonitis you have. They usually include abdominal pain and swelling. But it’s the complications that you want to watch out for. Since your peritoneum spreads throughout your abdomen and touches many organs, infections in your peritoneum can affect all of these organs. It can also spread to your bloodstream and become systemic throughout your body.
Peritonitis can be mild to severe, and it can be localized in one place or diffuse throughout your peritoneum. However, healthcare providers always treat peritonitis as an emergency because it can become severe very quickly, especially if it’s infectious. An infection that spreads to your bloodstream (septicemia) can cause your whole body to go into a kind of shock and shut down vital organs (septic shock).
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Bacterial infections are the most common cause, especially secondary infections that spread from one of your organs. This can happen if you have a hole in your stomach or intestines that lets bacteria from your gastrointestinal tract enter your peritoneal cavity. A burst appendix from appendicitis is another common cause. Less commonly, bacterial peritonitis can start in your peritoneum itself.
Inflammation is often caused by an infection, but sometimes it’s just a chemical reaction to different body fluids. For example:
Infectious peritonitis can be either primary or secondary. Primary infectious peritonitis is caused by an infection that originates in your peritoneum itself. Secondary bacterial peritonitis spreads to your peritoneum from somewhere else in your body.
Primary infection is less common than secondary infection. It usually happens in one of two ways:
Secondary infection is the most common cause of peritonitis. It can be caused by:
Typical symptoms include:
If you have an infection, you may also have:
If you have ascites, you may also have:
Yes, it’s possible. Abdominal pain and other symptoms from the original condition that causes your peritonitis can disguise the symptoms of peritonitis itself. Some people have less sensation in their peritoneum if it’s been swollen with ascites for some time. They may not notice the difference if ascites becomes infected. It’s important for healthcare providers to stay alert to the risk of peritonitis.
Your healthcare provider will begin by asking about your medical history and current conditions. They will physically examine your abdomen and check to see if it is swollen, sensitive to the touch or rigid. If it is, they will follow up with a blood test to check for evidence of inflammation or infection (high white blood cell count). They may also take images of your abdominal organs to look for causes of peritonitis.
One way to confirm and identify the specific infection in your peritoneum is to draw out some of the fluid with a needle (paracentesis) and test it in a lab (peritoneal fluid culture). In cases of ascites, this can also help relieve pressure in your abdomen. In more difficult cases, when your healthcare provider can’t find the cause of your peritonitis, they may need to explore your abdominal cavity in surgery to find and fix the problem.
Treatment typically begins with IV fluids and broad-spectrum antibiotics to treat or prevent infection. If later tests reveal the exact bacterium or pathogen causing your infection, you may be given a more specific antibiotic for it then. Your healthcare team will work to stabilize your condition before moving on to address the underlying cause. Some causes will require emergency surgery to repair.
Peritonitis can lead to:
Your outlook depends on the cause and type of peritonitis you have and how quickly it’s treated. Early recognition is important to be able to control peritonitis before it becomes complicated. Treatment is usually effective, but some complications, such as organ damage, may be lasting. Those with weaker immune systems, due to various chronic diseases, are more at risk for complications than others.
A note from Cleveland Clinic
Peritonitis can develop very suddenly, and it’s important to act quickly when it does. Your symptoms and pain levels may or may not seem like an emergency. Abdominal pain can have many different causes, some more serious than others, but if you're in doubt, it doesn’t hurt to check. If you’ve had slowly building symptoms for a while and they suddenly get worse, seek medical attention right away.
Last reviewed by a Cleveland Clinic medical professional on 11/02/2022.
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