Peritoneum

Layers The peritoneum is one continuous sheet, forming two layers and a potential space between them: the peritoneal cavity. The outer layer, the parietal peritoneum, is attached to the abdominal wall and the pelvic walls. The tunica vaginalis, the serous membrane covering the male testis, is derived from the vaginal process, an outpouching of the parietal peritoneum. The inner layer, the visceral peritoneum, is wrapped around the visceral organs, located inside the intraperitoneal space for protection. It is thinner than the parietal peritoneum. The mesentery is a double layer of visceral peritoneum that attaches to the gastrointestinal tract. There are often blood vessels, nerves, and other structures between these layers. The space between these two layers is technically outside of the peritoneal sac, and thus not in the peritoneal cavity. The potential space between the parietal and visceral peritoneum is the peritoneal cavity, filled with a small amount (about 50 mL) of slippery serous fluid that allows the two layers to slide freely over each other. The right paracolic gutter is continuous with the right and left subhepatic spaces. The epiploic foramen allows communication between the greater sac and the lesser sac. The peritoneal space in males is closed, while the peritoneal space in females is continuous with the extraperitoneal pelvis through openings of the fallopian tubes, the uterus, and the vagina. There are two main regions of the peritoneal cavity, connected by the omental foramen. • The greater sac, represented in red in the diagrams above. • The lesser sac, represented in blue. The lesser sac is divided into two "omenta": • The lesser omentum (or hepatogastric) is attached to the lesser curvature of the stomach and the liver. • The greater omentum (or gastrocolic) hangs from the greater curvature of the stomach and loops down in front of the intestines before curving back upwards to attach to the transverse colon. Peritoneal folds develop from the ventral and dorsal mesentery of the embryo. ==Clinical significance==

Imaging assessment CT scan is a fast (15 seconds) and efficient way in visualising the peritoneal spaces. Although ultrasound is good at visualizing peritoneal collections and ascites, without ionising radiation, it does not provide a good overall assessment of all the peritoneal cavities. MRI scan is also increasingly used to visualise peritoneal diseases, but requires long scan time (30 to 45 minutes) and prone to motion artifacts due to respiration and peristalsis and chemical shift artifacts at the bowel-mesentery interface. Those with peritoneal carcinomatosis, acute pancreatitis, and intraabdominal sepsis may not tolerate prolonged MRI scan. Peritoneal dialysis In one form of dialysis, called peritoneal dialysis, a glucose solution is sent through a tube into the peritoneal cavity. The fluid is left there for a prescribed amount of time to absorb waste products, and then removed through the tube. The reason for this effect is the high number of arteries and veins in the peritoneal cavity. Through the mechanism of diffusion, waste products are removed from the blood. Peritonitis Peritonitis is the inflammation of the peritoneum. It is more commonly associated to infection from a punctured organ of the abdominal cavity. It can also be provoked by the presence of fluids that produce chemical irritation, such as gastric acid or pancreatic juice. Peritonitis causes fever, tenderness, and pain in the abdominal area, which can be localized or diffuse. The treatment involves rehydration, administration of antibiotics, and surgical correction of the underlying cause. Mortality is higher in the elderly and if present for a prolonged time. Primary peritoneal carcinoma Primary peritoneal cancer is a cancer of the cells lining the peritoneum. ==Etymology==

"Peritoneum" is derived from via Latin. In Greek, means "around", while means "to stretch"; thus, "peritoneum" means "stretched over". ==Additional images==

Image:Gray403.png|Median sagittal section of pelvis, showing the arrangement of fasciæ Image:Gray1038.png|Horizontal disposition of the peritoneum in the lower part of the abdomen Image:Gray1125.png|Sagittal section through posterior abdominal wall, showing the relations of the capsule of the kidney Image:Gray1224.png|Topography of thoracic and abdominal viscera Image:Gray1039.png|Horizontal disposition of the peritoneum in the upper part of the abdomen Image:Cytology of normal mesothelium.jpg|Cytology of the normal mesothelial cells that line the peritoneum, with typical features. Wright's stain File:Histology of the mesothelial lining of a hernia sac.jpg|Histology of the peritoneal mesothelial lining, and underlying fibrous tissue. H&E stain. ==See also==