Understanding the Peritoneum

Peritoneum

• The peritoneum is a complex structure.
• Sonographers must understand it to correctly identify sites of pathologies.
• It's a serous membrane.
• It lines the abdomen and pelvis.
• It lines abdominal walls and contents.

Functions

• Holds viscera in position.
• Secretes lubricating fluid.

Components

• Parietal peritoneum: Lines abdominal and pelvic walls.
• Visceral peritoneum: Covers the organs.
• Continuous, like a deflated balloon.

Peritoneal Cavity

• Potential space between parietal and visceral peritoneum.
• No abdominal organs here.
• Contains ovaries and fimbriae ends of fallopian tubes.
• Contains peritoneal fluid (50-75mL is normal).

Peritoneal Cavity Subdivisions

• Greater sac: Large part, spans entire width of abdomen.
• Lesser sac (Omental bursa): Posterior to stomach, inferior to liver.

Peritoneal Reflection

• Peritoneum folds back on itself, creating a double layer.
• Different names based on connection: mesentery, omentum, and ligaments.

Mesentery

• Double fold of peritoneum.
• Connects viscera (bowel) to posterior abdominal wall.
• Small bowel mesentery, transverse mesocolon, sigmoid mesocolon, and mesoappendix.

Omentum

• A double fold of peritoneum.
• Connects stomach to adjacent organs or abdominal walls.
• Greater omentum: apron-like fold, attached to greater curvature of stomach.
• Lesser omentum: connects lesser curvature of stomach and liver.

Ligaments of the Lesser Omentum

• Hepatoduodenal ligament: Connects liver to first part of duodenum, contains the portal triad (hepatic artery, portal vein, and common bile duct).
• Gastrohepatic ligament: Connects lesser curvature of the stomach to the liver.

Epiploic Foramen (Foramen of Winslow)

• Connection between greater and lesser sacs.
• Posterior to the lesser omentum.
• Anterior to the pancreas.
• Superior to the first part of the duodenum.
• Inferior to the caudate lobe of the liver.

Other Ligaments

• Coronary ligament: Attaches liver to the inferior surface of the diaphragm.
• Falciform ligament: Connects anterior surface of liver to anterior abdominal wall and umbilicus. Separates right and left subphrenic spaces.
• Splenorenal (lienorenal) ligament: Connects spleen to posterior abdominal wall and supports the left kidney.
• Phrenicocolic ligament: Attaches left colic/splenic flexure to the diaphragm, supporting the spleen and preventing fluid communication.

Spaces

• Right and left subphrenic spaces: Between diaphragm and superior surface of the liver, separated by the falciform ligament.
• Subhepatic space (Morrison's pouch): Between liver and right kidney.
• Perisplenic space: Around the spleen.
• Paracolic gutters/inframesocolic spaces: Areas below the transverse mesocolon, around the small bowel mesentery, and between ascending/descending colon and abdominal wall.
• Pelvic cul-de-sacs: Vesicouterine, rectouterine, and rectovesical spaces.

Ascites

• Accumulation of fluid in the peritoneal cavity.
• Transudate: clear fluid.
• Exudate: "stuff," cloudy fluid.
• Commonly found in dependent spaces: pelvic cul-de-sac, right paracolic gutter, and Morrison's pouch.

Retroperitoneum

• Contains: aorta, IVC, kidneys, adrenals, pancreas, part of duodenum (2nd & 3rd parts), ascending and descending colon.
• Retroperitoneal spaces: anterior, perirenal/perinephric , posterior pararenal spaces.

This quiz covers the anatomy and functions of the peritoneum, a vital serous membrane lining the abdomen and pelvis. Explore the various components, the peritoneal cavity, and its subdivisions to deepen your understanding of this complex structure. Ideal for sonography students and healthcare professionals.