A 65-Year-Old Man With a Hugely Distended Abdomen

Prashanth Rawla, MD; Jeffrey Pradeep Raj, MD

Disclosures

October 24, 2019

The diagnosis of ACPO is usually a diagnosis of exclusion that largely depends on the history, clinical signs and symptoms, and findings from radiographic studies.[15] The most important diagnostic tool is plain radiography, which reveals a massive colonic dilatation that involves the cecum, ascending colon, and transverse colon. Other ACPO features include well-defined colonic septa, preservation of haustral markings, and a smooth contour of the inner lumen.[1,10] This helps to rule out causes of mechanical obstruction, small bowel obstruction, or frank perforation.[1] The cecum is the most common region for perforation,[16] and plain radiography enables measurement of the cecal diameter; a cecal dilatation of approximately 12 cm is suggestive of an impending perforation.[17] Contrast enema may be used if plain radiography does not rule out mechanical obstruction of the colon. Similarly, a CT scan may help in ruling out perforation, obstruction, or toxic megacolon.[18] Laboratory studies may indicate investigation for leukocytosis, electrolyte imbalance, and renal insufficiency or azotemia.[19]

The goals of treatment include pain relief, relief of symptoms associated with gut motility, and nutritional support.[20] Thus, management can be classified as conservative, including supportive care and pharmacologic therapy, colonoscopic decompression, and surgical intervention.[20] Patients are advised to eat nothing by mouth. Once perforation and ischemia are ruled out, any underlying cause such as congestive heart failure, sepsis, or respiratory failure should be aggressively treated.[21] Electrolyte imbalance should be corrected by appropriate intravenous management.[21]

Nasogastric decompensation is advised using a nasogastric tube, and drugs that are known to inhibit gastric motility should be reduced or discontinued.[21] In cases of impending perforation, incentive spirometry, intermittent positive pressure ventilation, and airway ventilation should be avoided. Other less effective measures include repeated enemas, use of rectal tubes, and rigid sigmoidoscopy.[22] Pharmacologic therapy represents another important part of conservative management. This involves the use of prokinetic agents (eg, metoclopramide, cisapride)[23] and cholinesterase inhibitors (eg, neostigmine).[24] Cathartic agents such as lactulose, low-dose polyethylene glycol, or daily bisacodyl suppositories to induce rectal emptying can facilitate improvement of symptoms and prevent recurrences.[25]

A flexible colonoscopy, on the other hand, serves a diagnostic and therapeutic purpose by ruling out mechanical obstruction, performing colonic decompression, and obtaining biopsy if a colonic mass is present.[4,10] This procedure is safe and effective; a retrospective study concluded that colonoscopic decompression is superior to neostigmine administration.[26] However, the procedure has certain technical difficulties when compared with other elective diagnostic colonoscopies. These include an inability to prepare the bowel before the procedure and subsequent lack of visibility, minimal air insufflation to avoid the risk of further cecal dilatation, and risk of perforation.[27] However, recurrence after a single decompression is common (18%-65%)[10,26,28] and can be decreased by placing indwelling decompression tubes in the proximal colon.[29] However, these catheters can get blocked. An alternative approach is to use serial colonic decompression.[27,28,29]

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