Peritoneum

What is the peritoneum?

Your peritoneum is a membrane, a sheet of smooth tissue that lines your abdominopelvic cavity and surrounds your abdominal organs. It pads and insulates your organs, helps hold them in place and secretes a lubricating fluid to reduce friction when they rub against each other. Your parietal peritoneum lines your abdominal and pelvic walls and your visceral peritoneum wraps around your organs. Your peritoneal cavity is the space in between.

What is the function of the peritoneum?

Your peritoneum has several functions, some of which researchers are still learning about. It provides:

• Insulation. Layers of the peritoneum contain fat that warms and protects your organs.
• Lubrication. Peritoneal fluid lubricates your organs inside of your peritoneal cavity (the ones that move).
• Structure. Ligaments in your peritoneum connect your organs to each other and attach your intestines to your back abdominal wall.
• Blood, lymph and nerve supply. Nerves and vessels run through the layers of your peritoneum.
• Immunity. Your peritoneum serves as a barrier to injury and pathogens in your abdominal cavity. It recognizes invasive particles and sends in white blood cells to target them. It filters fluids in your peritoneal cavity and drains waste products away. The tissue also has rapid healing properties to repair its own injuries. Researchers are still exploring these properties.

Where is the peritoneum located?

Your abdominopelvic cavity is between your diaphragm and your pelvic floor. It includes your abdominal cavity and pelvic cavity. Your parietal peritoneum lines the walls of this cavity. Your visceral peritoneum wraps around your abdominal organs, particularly your stomach, liver, spleen and parts of your small and large intestines. Organs inside of your visceral peritoneum are called “intraperitoneal.” The others are “retroperitoneal.”

What is the structure of the peritoneum?

Your peritoneum is a serous membrane (the type that secretes serum). Tissue of this kind lines several of your body cavities and is generally known as mesothelium. It’s composed of epithelial cells on the top layer with connective tissue underneath. The epithelial cells secrete and absorb fluid, filter out particles and carry blood, lymph and nerve supply. The connective tissue holds everything together. It attaches some organs to your abdominal wall and suspends others inside the cavity.

Formations

Your visceral peritoneum folds upon itself as it wraps around your organs, creating double layers and pouches here and there. A large double layer called the omentum covers the front of your abdomen like an apron. A double layer in the back called the mesentery attaches your intestines to your back abdominal wall. The fat between the layers (adipose tissue) provides extra insulation and protection and carries neurovascular supply to your organs.

Nerve supply

Your visceral peritoneum that covers your abdominal organs shares the same autonomic nerve supply as those organs. It perceives a visceral type of pain, which is diffuse and hard to localize. It feels the stretch when your digestive organs are distended with food or gas. It also perceives chemical irritants, such as blood or bile leaks. Your parietal peritoneum shares the same somatic nerve supply as your abdominal wall that it covers. It perceives localized pressure, pain and temperature.

What conditions or disorders affect the peritoneum?

• Peritonitis. Inflammation of the peritoneum is called peritonitis. An infection inside of your peritoneal cavity often causes peritonitis, but it can also be an early indicator of many different gastrointestinal diseases. Peritonitis is treated as an emergency because of the absorbent nature of the peritoneum. An infection in your peritoneal cavity can be absorbed into your general bloodstream and become systemic throughout your body (septicemia).
• Ascites. Ascites is a buildup of excess fluid in your peritoneal cavity. It causes unexplained swelling in your abdomen. It’s usually a symptom of late-stage liver disease (cirrhosis), which creates hypertension in the portal vein in your abdomen, causing your veins to leak. Sometimes, it’s a symptom of congestive heart failure or cancer.
• Hernia. A hernia occurs when tissue from inside one of your body cavities pushes through the muscle wall into another. Most hernias occur through one of your abdominal walls, and the tissue most frequently involved is the peritoneum. Even when one of your visceral organs pushes through, it’s likely wrapped in the peritoneum. Hernias don’t usually harm your peritoneum, unless they become cut off from blood supply. But they may require surgery to repair.
• Abdominal adhesions. Abdominal surgery that cuts through your peritoneum can cause bands of tough scar tissue to form in it. Abdominal adhesions don’t always cause problems, but if they develop in the nooks and crannies between your organs, they can block the free movement of your organs and possibly obstruct movement inside of them. The most serious risk they can cause is a bowel obstruction. If your intestines are blocked, food can’t come through or out.
• Sclerosing mesenteritis (mesenteric panniculitis). This rare condition affects the fatty tissue in your mesentery, the fold of your peritoneum that attaches your small intestine to the back wall of your abdomen. It’s similar to a widespread case of abdominal adhesions in your mesentery. For reasons not well understood, chronic inflammation of the tissue leads to widespread scarring (fibrosis). Fibrosis can stop the flow of blood through the tissue (necrosis), and sometimes, it causes a bowel obstruction.
• Mesenteric lymphadenitis. Lymphadenitis is inflammation and swelling of your lymph nodes. It’s called mesenteric lymphadenitis when it occurs in your mesentery. It’s usually a symptom of infection. Lymph nodes help filter out germs and pathogens when your immune system is activated. It may cause pain and fever, but it’s usually temporary.
• Cancer. Cancer in the abdominopelvic organs easily spreads to your peritoneum. This is called peritoneal carcinomatosis. Occasionally, cancer can also originate there. Primary peritoneal cancer and peritoneal mesothelioma (cancer of the mesothelium) are two examples. A rare type of cancer called pseudomyxoma peritonei secretes a mucus-like substance that fills your peritoneal cavity. Any cancer in your peritoneum can also spread to the organs that it touches.

How do I know if something is wrong with my peritoneum?

Abdominal pain and swelling are the most common symptoms of any condition affecting your peritoneum. Pain that feels vague or diffuse throughout your abdomen could be coming from your visceral peritoneum, the inside layer. Pain that’s more intense may indicate your outside parietal layer is irritated. Abdominal pain has many causes, but many of them do involve your peritoneum.

What medical tests can check on the health of my peritoneum?

• Peritoneal fluid analysis. Healthcare providers analyze a sample of your peritoneal fluid to diagnose peritonitis or ascites. They take a sample by inserting a hollow needle into your peritoneal cavity and drawing a small amount. Then, they send it to the lab. By analyzing the contents, they can identify fluid caused by inflammation or by leaking blood vessels. They can also find evidence of infection, cancer or chemicals leaking from one of your organs.
• Peritoneal biopsy. Sometimes, your healthcare provider may need to analyze a sample of your peritoneal tissue. They can take the sample using a special needle inserted into your abdomen (needle biopsy). They can also take a sample during a laparoscopy, an exploratory exam of your abdominal cavity using a tiny camera inserted through a tiny incision. They may suggest a laparoscopy and biopsy if they need to take a look inside at what’s going on in your abdomen.

What medical treatments involve the peritoneum?

• Peritoneal dialysis. The peritoneum is so effective at filtering waste products that sometimes healthcare providers use it as a method of dialysis to treat people living with kidney failure. Dialysis does the work of your kidneys by removing waste products and excess fluid from your blood. During the process, you or your healthcare provider fill your peritoneal cavity with a fluid solution. Your peritoneum filters the fluid, and later, you or your healthcare provider drain it out.
• Hyperthermic Intraperitoneal Chemotherapy (HIPEC). HIPEC is a new, targeted form of chemotherapy that takes advantage of the absorbent properties of your peritoneum. It’s a concentrated, heated chemotherapy solution that’s delivered directly into your peritoneal cavity. If you have localized cancer in your peritoneal cavity, HIPEC can treat it locally. This is a unique alternative to traditional chemotherapy, which is delivered systemically through your bloodstream and is associated with many side effects. It may also be more effective.
• Cytoreductive/debulking surgery. Cancer in your abdominopelvic cavity will usually be treated with surgery, as well as chemotherapy. Cytoreductive or debulking surgery attempts to remove as many cancer cells as possible, wherever they’re found. Sometimes, that means removing part or all of your peritoneum (peritonectomy). The most common part affected is your omentum. Certain types of cancer tend to spread there first, and sometimes, an omenectomy removes it.

How can I help take care of my peritoneum?

Peritoneal diseases are hard to predict or prevent, but you can help take care of yourself by taking your abdominal pain seriously. Don’t be shy about seeing your doctor, even if you’re not sure if you should be concerned. You can’t always tell by the severity of your symptoms how serious they are. Some of the most serious diseases only have mild or vague symptoms.

A note from Cleveland Clinic

Your peritoneum is what lies between your skin and most of your visceral organs. It encloses them in at least one and sometimes several layers. It offers protection, insulation, structure and blood and nerve supply. It also has powerful healing and immunity functions. By covering your organs, (peritoneum means “to stretch around,”) it acts as a sentinel to infection anywhere in your abdominopelvic cavity. Inflammation in your peritoneum could be the first alarm that draws your attention to an unsuspected condition affecting one of your organs.