Peritoneal Cavity: Organs, 4 Great Functions & Structure

Peritoneal cavity is the space between the parietal and visceral peritoneum (the peritoneum is a membrane that lines along the abdominal cavity and covers the organs in the abdomen, it also help blood vessels and lymph to pass to and fro the viscera by acting as a passage). The cavity has a thin film of fluid which is made up of water, electrolytes, antibodies and leukocytes.

The peritoneal fluid is a lubricant that helps the abdominal viscera to move freely, the antibodies in the cloud also helps to fight bacteria and other infections. Although the it has a thin film of fluid, it is considered as space because excess fluid other than the thin film of fluid it has can pool in the space and this can lead to a medical condition known as ascites. 


We already know that the peritoneum is a membrane that lines along the abdominal cavity and covers the abdominal organs. This membrane is divided into two parts – the parietal peritoneum and the visceral peritoneum. The parietal peritoneum encloses the abdominal wall while the visceral peritoneum encloses the organs in the abdominal cavity.

The space between these two membranes is known as the peritoneal cavity. It is the largest sac that is filled with the largest fluid, in fact this cavity produces and discharges 50 ml of fluid every day. The fluid is also of benefit to the body, it lubricates and can also fight against infections. 


The peritoneal cavity can be found in the abdominal section of the body. It is a space between a membrane found in the abdomen, this means that it is in the abdomen. 

Peritoneal Cavity
Peritoneal Cavity


It contains organs like:

  • Stomach
  • Spleen
  • Jejunum
  • Liver
  • Sigmoid colon
  • Ileum
  • Transverse colon
  • First and fourth parts of the duodenum
  • Gallbladder
  • Tail of the pancreas
  • Cecum, although this organ is not covered in the visceral peritoneum, it is considered as inside of the peritoneal cavity because it can move around the cavity.
  • Appendix
  • Upper part of the rectum.


It is not just a space between membranes, it has many functions it performs. These functions are:

  1. The fluid in the sac acts as lubricant and helps to reduce friction for all the internal organs.
  2. It provides free movements for organs like the intestines without any obstructions.
  3. The fluid has antibodies that can fight against infections in the internal organs. This helps to keep the surrounding organs safe from harm.
  4. The peritoneal cavity can store fats.


The peritoneal cavity has fluid in it, this is normal. The fluid is a lubricating and has antibiotic properties in it. The most important function of this cavity fluid is to help with the movement of the organs in the abdominal cavity and reduce friction.

Negative pressure in the body coupled with how the diaphragm moves causes the peritoneal fluid to move towards the diaphragm. The fluid is usually small in a healthy body and it secretes. However, some health problems can cause excess fluid to pool inside the cavity, this condition is known as an ascites. 


The peritoneal cavity is divided into two sacs – the greater sac and the lesser sac. The greater sac from the name is made up of majority of the cavity while the lesser sac has smaller cavity. Let us try to explain both terms.

1. Greater Peritoneal Sac

This is made up of the greater part of the cavity, it is subdivided into two compartments by the mesentery of the transverse colon. The two compartments are:

Supracolic compartment is the area above the mesentery of the transverse colon. It is made of the liver, stomach and spleen. 

Infracolic compartment is found below the transverse colon and it is made up of the descending and ascending colon including the small intestine. The mesentery of the small intestine divides the infracolic compartment into left and right spaces. 

The paracolic gutters connect both the supracolic and infracolic compartments. The paracolic gutters are open spaces between the colon and the abdominal wall. 

2. Lesser Sac

Another name for this sac is the omental bursa, it lies further back to the stomach and lesser omentum. The lesser sac allows the free movement of the stomach against organs that are in front or behind it. The epiploic foramen connects the greater sac and the omental bursa. The epiploic foramen is an opening in the omental bursa and it lies at the back of the hepatoduodenal ligament (a thick structure that forms part of the lesser omentum)


The pelvic organ differs in person to person, this is due to the difference in sex. The structure of the pelvis is different and this makes the cavity including the most distal portion of the cavity to differ as well. 

Peritoneal Cavity in Male

Males have a rectovesical pouch, this pouch is a pocket that lies between the rectum and bladder in males (Wikipedia, 2022). The peritoneal cavity is completely closed by this pouch in male. 

Peritoneal Cavity in Female

There are two things to take note of when talking about female pelvic organ and the peritoneal cavity. 

• The rectouterine pouch or pouch of Douglas is an extension of the peritoneum that lies between the rectum and the back of the uterine wall. 

• Vesicouterine pouch is a pocket that lies between the front of the uterus and the bladder. 

In females, the peritoneal cavity is not closed as the fallopian tubes open into the peritoneal cavity thereby making a pathway between the abdominal cavity and the genital tract. The structure of the peritoneal cavity in the female body makes it easier for the peritoneum to become infected and inflamed as any infection to the vagina, fallopian tubes or uterus can affect the peritoneum. 


The abdominal cavity is very different from the peritoneal cavity, they are both found in the body but have different functions and structure. The abdominal cavity is the largest hollow space found in the body. The cavity starts from the upper part which is the diaphragm, connective tissues and muscles that separates it from the chest area while it ends at the upper part of the pelvic. The abdominal cavity contains the liver, spleen, pancreas, kidneys, adrenal glands and the digestive tract. 

The abdominal cavity and its organs are covered by the peritoneum, the space between the two parts of this peritoneum is called the peritoneal cavity. The fluid from the peritoneal cavity helps to lubricate the organs in the abdominal cavity and protect them from infections. The peritoneal cavity cannot exist without the abdominal cavity. The functions of the peritoneal cavity can only be useful when there is an abdominal cavity. 


The cavity can become disordered or have problems which are considered as medical issues. Some of these disorders are:

1. Ascites

When there is excess accumulation of fluid in the peritoneal cavity, this is known as ascites, this is mostly caused by liver failure. The excess fluid makes the belly to become bigger and swollen. 

Other causes of ascites are:

  • Failure of the heart
  • Malnutrition
  • Cancer of the gastrointestinal tract
  • Injuries that leads to internal bleeding.

Symptoms of ascites are:

  • Bloating and swelling of the belly
  • Nausea
  • Pain from inside of the abdomen or the outer cavity
  • Difficulty in breathing due to pressure on the lungs.

Treatment methods for ascites are:

  • Water pills to flush out the excess fluid and sodium from the body.
  • Reducing sodium intake from 4,000 milligrams a day to less than 2,000 milligrams.
  • Paracentesis, a procedure that involves putting a needle in the swollen abdomen to drain out the fluid.
  • Transjugular intrahepatic portosystemic shunt (TIPS) allows inserting a stent into the liver through a vein. When the stent is inflated, a passage is formed to bypass the liver.
  • Liver transplant is done when the liver has damaged due to severe cirrhosis.


The peritoneum can become infected when there is a bacterial contamination in the gastrointestinal tract or during any open surgical incision on the peritoneum. The fluid pours into the peritoneal cavity, makes the cavity to expand and cause pain too.

Symptoms of the peritonitis are:

  • Tenderness of the skin around the abdomen
  • Vomiting
  • Constipation
  • Fever
  • Nausea
  • Difficulty in passing out urine
  • Difficult bowel movement

Treatment for peritonitis are: 

  • Antibiotics that can be administered intravenously
  • Antifungal medicines
  • Medications that are injected into the peritoneal space
  • Surgery if the disorder is caused by perforated ulcer, appendix or any tissue.


Peritoneal cavity is a space between membranes in the abdominal cavity. It contains fluid that are of benefits to the abdominal cavity and the organs in it. The peritoneal cavity has many compartments which makes it easier to distinguish the parts. The structure of the peritoneal cavity differs from male and female due to the structure of the pelvic organ. Certain disorders can cause problems to the cavity which can lead to health issues. 

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