Areas - Abdominal Cavity

Question 1

What is the abdominal cavity?

Answer 1

It is also known as the peritoneal cavity, located between the parietal and visceral peritoneum.

It contains a small amount of peritoneal fluid, consisting of water, electrolytes, leukocytes and antibodies to fight infection.

The peritoneal cavity is a potential space because excess fluid can accumulate here - as in the case of ascites.

Question 2

What are the subdivisions of the peritoneal cavity?

Answer 2

1) Greater sac
2) Lesser sac

Question 3

Greater sac

Compartments?

Organs?

Answer 3

The greater sac can be divided further into two compartments by the mesentery of the transverse colon:

1) Supracolic compartment - contains the stomach, liver and spleen.
2) Infracolic compartment - contains the small intestin, and the ascending and descending colon.

The two compartments are connected by paracolic gutters, which lie between the posterolateral abdominal wall and the lateral aspect of ascending or descending colon.

Question 4

Clinical relevance: subphrenic abscesses?

Answer 4

The subphrenic recesses are potential spaces between the diaphragm and the liver, in the supracolic compartment. There are left and right subphrenic recesses, separated by the falciform ligament of the liver.

Subphrenic abscesses refer to a collection of pus in the left and right recesses. They are more common in the right due to the increased frequency of appendicitis and ruptured duodenal ulcers (pus can accumulate in the recess from a burst appendix via the paracolic gutter).

Question 5

Lesser sac (omental bursa)

Location?

Answer 5

Lies posterior to the stomach and the lesser omentum. It allows the stomach to move freely along the structures adjacent to it.

The lesser sac is connected to the greater sac via the an opening in the omental bursa - the epiploic foramen (of Winslow).

This foramen is situated posterior to the free edge of the lesser omentum.

Question 6

Structure of the peritoneal cavity in the pelvis?

Male vs female?

Answer 6

Due to the presence of different pelvic organs, the peritoneal cavity differs between the two sexes.

This is of clinical relevance because when a person stands up, any superfluous fluid (e.g. blood, pus etc.) will accumulate in the inferior aspect of the peritoneal cavity.

Male

In males, the rectovesical pouch is a double folding of peritoneum located between the rectum and bladder. The peritoneal cavity is completely closed in males.

Female

In females, there are two areas of note:

1) Rectouterine pouch (of Douglas) - double folding of peritoneum between the rectum and the posterior wall of the uterus.
2) Vesicouterine pouch - double folding of peritoneum between the anterior surface of the uterus and the bladder.

The peritoneal cavity is not completely closed off in females. The uterine tubes open into the peritoneal cavity, providing a potential pathway from the female genital tract and the abdominal cavity. Clinically, this could mean infections of the vagina, uterus, uterine tubes or the peritoneum.

This is rare however due to a mucous plug of the external os of the uterus, preventing the passage of pathogens to enter the uterus.

Question 7

Clinical relevance: sampling of fluid - culdocentesis?

Answer 7

Extraction of fluid from the rectouterine pouch (of Douglas), via a needle through theposterior fornix of the vagina.

Used to extract fluid from the peritoneal cavity to drain an abscess in the rectouterine pouch.

Question 8

Clinical relevance: sampling of fluid - paracentesis?

Answer 8

A procedure to drain fluid from the peritoneal cavity.

A needle is inserted through the anterolateral abdominal wall into the abdominal cavity. The needle must be inserted superior to the urinary bladder and the clinician must be careful to avoid the inferior epigastric artery.

It is used to drain ascitic fluid, diagnose the cause of the ascites to check for certain types of cancer that may metastasise via the peritoneum e.g. liver cancer.

Question 9

Clinical relevance: ascites?

Answer 9

Refers to the accumulation of fluid within the peritoneal cavity. It is typically caused by portal hypertension (secondary to liver cirrhosis).

Other causes include malignancy of the GI tract, malnutrition, heart failure, and mechanical injuries which result in internal bleeding.

Clinical features of ascites include abdominal distension, abdominal discomfort, nausea, and dyspnoea due to the pressure on the lungs from the enlarged abdominal cavity.

Question 10

Clinical relevance: peritonitis?

Answer 10

Inflammation of the peritoneum.

Can occur due to bacterial contamination during a laparotomy (open surgical incision of the peritoneum) or it can happen secondary to an infection elsewhere in the GI tract (e.g. a ruptured appendix, acute pancreatitis or a gastric ulcer eroding through the wall of the stomach).

Exudation of fluid into the periotneal cavity causes the cavity to expand, and due to somatic innervation of the parietal peritoneum it causes pain.

Clinical features can include:

1) pain and tenderness overlying skin
2) anterlateral abdominal muscles contract to protect the viscera (known as guarding)
3) fever, nausea, vomiting and constipation
4) Patients may sit with their knees flexed in an effort to relax the anterolateral abdominal wall muscles