Nontraumatic large bowel perforation: spectrum of etiologies and CT findings

Abstract

Large bowel perforation is an abdominal emergency that results from a wide range of etiologies. Computed tomography is the most reliable modality in detecting the site of large bowel perforation. The diagnosis is made by identifying direct CT findings such as extraluminal gas or contrast and discontinuity along the bowel wall. Indirect CT findings can help support the diagnosis, and include bowel wall thickening, pericolic fat stranding, abnormal bowel wall enhancement, abscess, and a feculent collection adjacent to the bowel. Common etiologies that cause large bowel perforation are colon cancer, foreign body aspiration, stercoral colitis, diverticulitis, ischemia, inflammatory and infectious colitides, and various iatrogenic causes. Recognizing a large bowel perforation on CT can be difficult at times, and there are various entities that may be misinterpreted as a colonic perforation. The purpose of this article is to outline the MDCT technique used for evaluation of suspected colorectal perforation, discuss relevant imaging findings, review common etiologies, and point out potential pitfalls in making the diagnosis of large bowel perforation.

Gastrointestinal perforation: clinical and MDCT clues for identification of aetiology

“…Axial images of 2-mm slice thickness should be obtained at a non-contrast and a portal phase (100 mL, 70-80 s following intravenous administration of lowosmolarity iodinated contrast medium) [1,[6][7][8][9][10][11][12]. In suspected ischemic infarction, a biphasic technique in the arterial and portal phases, following 120-150 mL of contrast, is required for the detection of vascular changes and perfusion abnormalities [3].…”

“…In blunt trauma, an added late 3-5-min phase is needed to exclude low-flow active bleeding [3,13]. Review of images in multiple window settings is indispensable, since extraluminal air and foreign bodies are better visualised in lung and bone window settings, respectively [2,[6][7][8][9][10][11][12][14][15][16][17][18]. Multiplanar reformations can greatly increase the accuracy in localisation of perforation site [2,[6][7][8][9][10][11][12][14][15][16][17][18].…”

“…Evaluation of colorectal perforation following contrast per os requires a preparation time of 3 h, especially in patients with diminished bowel motility [11]; thus, some institutions recommend administration of intrarectal contrast [10,11,13]. This should be performed cautiously and in small quantities to avoid further rupture of a friable colonic wall (i.e.…”

“…Malignancy is the commonest cause, accounting for 36% of perforations [48]. Perforation may also be iatrogenic (20%), diverticula-related (19%) and less commonly due to trauma, foreign body ingestion, faecal impaction, ischemia, inflammatory bowel disease, endometriosis, connective tissue disease, radiotherapy, drugs and spontaneous [4,6,7,10,11,49]. The site of perforation is often linked with its cause [4,8,10]; therefore, neoplastic, spontaneous, diverticular (in western countries), blunt trauma and ischemic perforations commonly occur on the left side of colon, whereas inflammatory bowel disease, diverticulitis (in eastern countries) and penetrating trauma perforations tend to be right-sided.…”

“…The rectosigmoid is most commonly affected in iatrogenic manipulations and foreign bodies [4,6]. The cecum may perforate when it reaches 12-14 cm in diameter as a result of a rapid increase in intraluminal pressure in bowel obstruction with a competent ileocaecal valve, toxic megacolon, stercoral colitis and acute colonic pseudo-obstruction [4,8,11]. Extraluminal gas limited in the pelvis or within retroperitoneal compartments suggests colorectal perforation with the exception of right-sided retropneumoperitoneum which may also result from duodenal perforation.…”