Perforated diverticulitis is a complication of diverticulitis and entails the rupture of an infected diverticulum in the large intestine, primarily the colon. Diverticulitis is a condition that involves a microbial inflammation of the diverticulum.
Diverticula are small pouches that develop in any part of the intestine and are mainly found in the colon. They are commonly observed during colonoscopy amongst the population aged over 60 years old. Diverticula alone are asymptomatic; however, inflammation may occur due to a fecal obstruction at the site of a diverticulum that causes infection of the latter, leading to a condition known as diverticulitis or diverticular disease. Perforation of an infected diverticulum is a grave complication that occurs when the inflamed pouch ruptures into the peritoneal cavity.
The symptoms caused by perforated diverticulitis are the same as those seen in any other case of intestinal perforation and subsequent peritonitis. The complication involves either free perforation with purulent peritonitis or fecal peritonitis, which correspond to Hinchey's classification of perforated diverticulitis as stage III and IV respectively .
In contradistinction to gastric or duodenal perforation, which lead to alarming, sudden-onset symptoms and generalized pain, perforated diverticulitis, which mainly affects the large intestine, may develop in the presence of pre-existing symptoms, related to the underlying disease (diverticulitis), such as pain in the lower mid- or left quadrant of the abdomen. The symptom of abdominal pain in the lower abdomen may increase in intensity over time, in cases of perforation, and tends not to be of sudden onset. It is also described by the patients as localized, and so is the abdominal tenderness caused by peritonitis. Additional symptoms that complete the clinical picture are vomiting, nausea and loss of appetite. All aforementioned symptoms are exacerbated with the progression of time, with the patients eventually presenting with generalized tenderness and pain in the abdominal area and distention. Generally, perforated diverticulitis is not a complication frequently observed in a clinical setting; even if it occurs, stages III and IV of Hinchey's classification are the less common types of complicated diverticular disease  .
Patients with a history of diverticulosis who report a gradually increasing sensation of pain in the lower abdomen, tenderness in the same region and distention are potential candidates for perforated diverticulitis. The physical examination is expected to reveal:
With regard to imaging modalities that can aid in the diagnosis of perforated diverticulitis, the first step is a plain abdominal radiograph. Intestinal perforation is illustrated in an x-ray by air, located in the subdiaphragmatic regions, a visible falciform ligament, and air-fluid levels. However, plain radiographs are not of much assistance in cases of a perforated diverticulum, since this type of condition does not lead to air that is visible in radiographs. Ultrasonography (US), on the other hand, is a valuable tool in order to detect a suspected perforation, since it can detect free air within the peritoneal cavity. It can also differentiate between a case of diverticular perforation, an appendicular perforation or a gastric perforation. Lastly, a computerized tomography scan (CT) can detect a diverticular abscess, localized perforated diverticula and a variety of alterations in the soft tissues adjacent to the colon, thus rendering a diagnosis possible. A CT scan can also help to evaluate the need for a conservative or surgical treatment in patients with diverticulosis and newly-occurring symptoms . Regarding blood laboratory tests, studies have detected a strong correlation of CRP> 200 mg/l and perforated diverticulitis .