Epiploic appendages are small adipose protrusions attached by a vascular stalk to the serosal surface of the colon. They frequently arise in association with colonic diverticula.
Their length is 0.5–5 cm, being the largest ones, those located near the sigmoid colon.
The most common sites of acute epiploic appendagitis, in order of decreasing frequency, are areas adjacent to the sigmoid colon, the descending colon, and the right colon.
The epiploic appendages are visible only when they are inflamed or surrounded by fluid (Fig. 1).
Each epiploic appendage is supplied by two small end arteries branching from the vasa recta longa of the colon and is drained by a tortuous vein passing through its narrow pedicle. Their limited blood supply, together with their pedunculated shape and excessive mobility, make epiploic appendages prone to torsion, kinking, or stretching with subsequent venous thrombosis (the venous component of the appendage is affected first because each appendage is supplied by paired arteries but drained by only one vein), that leads to ischemia.
In secondary epiploic appendagitis, the epiploic appendage is inflamed because of another process, such as diverticulitis (Fig. 22), appendicitis, pancreatitis, or cholecystitis.
Acute epiploic appendagitis is associated with obesity, hernia, and unaccustomed exercise.
The condition most commonly manifests in the 4th to 5th decades of life, predominantly in men.
Clinically, acute epiploic appendagitis manifests with acute onset of focal abdominal pain, which is typically pointed out by the patient with one finger, most often in the left lower quadrant. It may be mistaken clinically for acute diverticulitis (left lower quadrant, LLQ), for acute appendicitis (right lower quadrant, RLQ), for cholecystitis (right upper quadrant, RUQ) or for gynecological disease in women (lower abdomen area).
Unlike acute epiploic appendagitis, acute diverticulitis is more likely to manifest with evenly distributed lower abdominal pain and to be associated with nausea, fever, and leukocytosis.
Although most patients with acute epiploic appendagitis do not report any change in their bowel habits, a minority experience constipation or diarrhea.
The condition is self-limiting, and most patients recover with conservative management (NSAIDs) in less than 10 days. Rarely, acute epiploic appendagitis may result in adhesion, bowel obstruction, intussusception, intraperitoneal loose body, peritonitis, or abscess formation.