Recesses of the Peritoneal Cavity
The peritoneum is a continuous, glistening and slippery transparent serous membrane lining the abdominopelvic cavity, and investing the viscera of the abdomen and pelvis. Because it is “continuous”, it is made up of two layers, the parietal peritoneum which lines the internal surface of the abdominopelvic wall, and the visceral peritoneum investing the visceral of those regions. Between these two layers of peritoneum is a potential space called the peritoneal cavity, thus, within the abdomen the space is called the peritoneal cavity of the abdomen. The peritoneal cavity is a potential space of about one capillary thick and contains a thin film of peritoneal fluid composed of water, electrolytes, and other substances derived from the interstitial fluid in adjacent tissues. Primarily, this thin film of peritoneal fluid functions to lubricate the peritoneal surfaces, enabling the viscera to move over each other without friction, and allowing free movements of digestion. Also contained in this fluid are antibodies and leukocytes used to fight infection.
As the peritoneum wraps around the viscera, they form several fossae or spaces called recesses within the peritoneal cavity. These recesses are potential sites for internal herniation of the abdominopelvic viscera, and they are also of clinical significance because a length of the intestine may enter one and be constricted by the fold (peritoneum) at the entrance of the recess.
There are several of such recess within the peritoneal cavity of the abdomen and pelvis, however more prominent within the abdominal peritoneal cavity. Below are some of the known recesses of the peritoneal cavity, which are usually named according to the related viscera. However, three main groups of recesses are identified and they are:
- Duodenal recesses
- Caecal recesses
- Intersigmoid recess.
These are fossae formed around the fourth part of the duodenum and the duodenojejunal junction. They can be described as follows:
- Superior Duodenal Recess: This recess is occasionally present in association with an inferior duodenal recess. It lies to the left of the end of the fourth part of the duodenum, opposite the second lumbar vertebra, and behind a crescentric superior duodenal fold (i.e, the duodenojejunal fold). The superior duodenal recess varies in size but is commonly 2cm deep, admitting a fingertip.
- Inferior Duodenal Recess: This recess is usually present, and it’s often associated with a superior duodenal recess with which it may share an orifice. It lies to the left of the fourth part of the duodenum, opposite the third lumbar vertebra. It sits behind a non-vascular, triangular inferior duodenal fold (the duodenomesocolic fold). The inferior recess is usually about 3cm deep, admits one or more fingers and opens upwards towards the superior duodenal recess. Sometimes, it extends beyond the fourth part of the duodenum.
- Retroduodenal Recess: The retroduodenal recess is the largest of the duodenal recesses, but it is rarely present. It is about 8-10cm deep and bounded on both sides by duodenoparietal folds. It has a wide orifice which faces down and to the left. This recess lies behind the third and fourth parts of the duodenum in front of the abdominal aorta, and ascends nearly to the duodenojejunal junction.
- Paraduodenal Recess: The paraduodenal recess may occur in conjunction with superior and inferior duodenal recesses. It is rare in adults but is more commonly seen in newborn children. It lies a little to the left and slightly behind the fourth part of the duodenum, behind a falciform paraduodenal fold.
- Duodenojejunal Recess: This recess can also be referred to as the mesocolic recess. It typically occurs in 20% of adults, and when present is almost never associated with any other duodenal recesses. It is approximately 3cm deep and lies to the left of the abdominal aorta, between the duodenojejunal junction and the root of the transverse mesocolon. Above, it is bounded by the pancreas, on the left by the kidney, and below by the left renal vein. It has a circular orifice between two peritoneal folds, and faces down, and to the right.
- Mesentericoparietal Recess: This recess is rarely present. When present, it lies just below the third part of the duodenum and invaginates into the upper part of the mesentery towards the right. Its opening is large and faces the left, behind a fold of mesentery raised by the superior mesenteric artery.
The Caecal recesses are spaces formed by the peritoneum around the caecum. Following acute appendicitis, paracaecal recesses are common sites for abscess formation. Three caecal recesses are identified, and can be described as follows:
- Superior Ileocaecal Recess: This recess is usually present and well developed in children. It is formed by the vascular fold of the caecum which arches over the anterior caecal artery. The superior ileocaecal recess is often much reduced or absent in the aged, especially the obese. It is a narrow slit bounded in front by the vascular fold, behind by the ileal mesentery, below by the terminal ileum and on the right by the ileocaecal junction.
- Inferior Ileocaecal Recess: This fossa is well identified in youth but frequently obliterated by fat in adults. It is bounded in front by the ileocaecal fold, above by the posterior ileal surface and its mesentery, to the right by the caecum, and behind by the upper mesoappendix. Its orifice opens downwards to the left.
- Retrocaecal Recess: The retrocaecl recess lies behind the caecum. It varies in size and extent, and ascends behind the ascending colon, often being large enough to admit an entire finger. It is bounded anteriorly by the caecum (and sometimes the lower ascending colon), posteriorly by the parietal peritoneum and on each side by the caecal folds (parietocolic membranes) passing from the caecum to the posterior abdominal wall. The vermiform appendix frequently occupies (herniates) this recess when in the retrocaecal position.
The intersigmoid recess is present and persists in fetal life and in childhood, but may disappear later in life. It lies posterior to the apex of the V-shaped parietal attachment of the sigmoid mesocolon and it is funnel shaped. It varies in size from a slight depression to a shallow fossa. Its posterior wall is formed by the parietal peritoneum of the posterior abdominal wall. Occasionally the intersigmoid recess is within the layers of the sigmoid mesocolon, and is nearer to the bowel wall than the mesenteric root.