The peritoneal cavity is a specialized space within the abdomen. It is a potential area, meaning it is a collapsed space between two layers of membranes, not normally open. This cavity contains a small amount of fluid, which facilitates the smooth movement of internal organs. Understanding this cavity helps explain how internal structures are organized and how medical conditions can arise in the abdomen. This space is distinct from the larger abdominal cavity, which houses all abdominal organs.
Anatomy and Location
The peritoneal cavity is bordered by a continuous, thin membrane known as the peritoneum. This membrane consists of two primary layers. The outer layer, the parietal peritoneum, lines the inner surface of the abdominal and pelvic walls. The inner layer, the visceral peritoneum, directly covers and adheres to the surfaces of most abdominal organs, such as the stomach, liver, and intestines. The cavity encompasses organs like the stomach, spleen, and parts of the intestines. A notable anatomical difference exists between sexes; in males, the peritoneal cavity is completely closed, whereas in females, it has small openings via the fallopian tubes, providing a rare pathway to the external environment.
Purpose and Function
The peritoneal cavity maintains the health and function of abdominal organs, containing peritoneal fluid, a serous fluid secreted by the mesothelial cells lining the peritoneum.
This fluid acts as a lubricant, enabling organs to move smoothly against each other with minimal friction. This lubricating action is supported by surface-active phospholipids within the fluid.
The peritoneal fluid also performs protective functions. It cushions the organs, providing a barrier against injury. The fluid contains various immune cells, including leukocytes and antibodies, which contribute to the body’s immune response by targeting pathogens and supporting tissue repair.
Common Conditions and Procedures
Various medical conditions and procedures involve the peritoneal cavity. One condition is ascites, characterized by the abnormal accumulation of excess fluid. While a small amount of fluid is normal, ascites involves volumes greater than 25 milliliters, often caused by liver cirrhosis, cancer, or heart failure, leading to abdominal distension and discomfort.
Another condition is peritonitis, which is inflammation of the peritoneum. This serious condition is often caused by bacterial infection, such as from a ruptured appendix or stomach ulcer, or by leakage of fluids from internal organs. Symptoms include severe abdominal pain, tenderness, and fever, often requiring immediate medical attention.
Peritoneal dialysis is a medical treatment that utilizes the peritoneum’s natural filtering capabilities to remove waste products from the blood in individuals with kidney failure. A cleansing fluid, called dialysate, is introduced into the cavity through a catheter, where it absorbs waste from blood vessels in the peritoneum before being drained. Adhesions, which are bands of scar tissue, can also form within the peritoneal cavity, often as a result of inflammation or surgery, potentially leading to complications by restricting organ movement or causing fluid to become trapped.