Abscess in the Abdomen and Intra-Abdominal Locations

What is an intra-abdominal abscess?

An intra-abdominal abscess is a localized collection of pus in the abdominal cavity. The abscess is usually confined to a small area by a barrier formed by adhesions between the abdominal organs and the omentum (the fold of peritoneum that supports the organs). An intra-abdominal abscess is a serious surgical condition and it can result in a lengthy hospitalization and may also be life-threatening. The symptoms of intra-abdominal abscess are often vague which can sometimes delay patients from seeking medical attention or delay the diagnosis. This often increases the mortality and morbidity resulting from intra-abdominal abscess.

How does an intra-abdominal abscess develop?

Microorganisms enter the peritoneal cavity following an injury or disease of the abdominal organ. These microorganisms stimulate a response from the body’s protective mechanism with release of numerous inflammatory cells into peritoneal cavity. When there is release of inflammatory cells, the peritoneum, the omentum and abdominal organs tend to wall off the infection and localize the site of infection. This can lead to reduced oxygen in the affected area and promotes the growth of anaerobic bacteria. The process also reduces the effectiveness of immune cells to combat the infection at the site. The cellular and bacterial debris resulting from the actions of immune cells accumulate and enlarge the abscess cavity. Delay in treatment initiation can lead to progression of the abscess to a generalized infection with septicemia and shock.

Intra-abdominal Abscess Location

The peritoneum and omentum are important protective structures in the abdominal cavity. The peritoneal coverings of the intestines tend to stick together in the presence of infection in the abdominal cavity. The omentum also reacts during infection by forming adhesions to peritoneal surfaces that surround the focus of infection. These reactions can seal off the intra-abdominal infections leading to collection of pus in various localized spaces in the abdominal cavity. This is known as an abscess.

The major spaces in the peritoneal cavity are the :

• subphrenic spaces (spaces below the diaphragm)
• pelvis
• lesser sac
• right and left paracolic gutter

The different intra-abdominal abscess are located as follows :

• Sub-phrenic abscess – abscess in the spaces below the diaphragm
• Pelvic abscess – abscess in the recto-vesicle pouch in males and recto-uterine pouch in females
• Diverticular abscess – abscess in relation to perforated diverticulitis
• Appendicular abscess – abscess in relation to perforated appendicitis
• Retroperitoneal abscess – abscess in relation to kidney in peri-renal or para-renal spaces
• Hepatic abscess – abscess developing in liver
• Interloop abscess – abscess present in relation to the loops of small intestine
• Pancreatic abscess – abscess in infected pancreatic cyst

Subphrenic spaces are present below the diaphragm. It is formed in relation to the attachments of the liver. In a subphrenic abscess the subphrenic spaces is filled with pus.The important subphrenic spaces are the right and left subphrenic spaces (space between the diaphragm and the liver), right and left subhepatic spaces (spaces below the liver) and the Morison’s pouch or hepatorenal recess (space that separates liver and kidney).

The right and left paracolic gutters are the spaces situated between the posterior abdominal wall (back) and the colon. The paracolic gutters are connected to the subphrenic spaces above and pelvic space below. It can allow passage of infected peritoneal fluid from one space to the other intra-abdominal spaces.

An abscess in lesser sac can result from infections originating from pancreas or appendix. Movement of infected fluid from other spaces can also lead to development of an abscess in lesser sac.

The pelvic cavity of men and women differ due to the difference in the pelvic organs. In men, the  recto-vesical pouch lies between the rectum and urinary bladder. The corresponding structure in women is the recto-uterine pouch or pouch of Douglas, which lies between the rectum and the uterus. The infected peritoneal fluid, blood or pus from abdominal or pelvic organs tend to collect in the pelvic cavity. This can lead to abscess formation in the recto-vesical pouch in men and recto-uterine pouch in women.

There are potential spaces behind the peritoneum called retroperitoneal space where an abscess can form. The retroperitoneal spaces comprise of perirenal and pararenal spaces. Abscess developing in relation to the kidney can collect in these spaces.