An 80-year-old male patient is recovering from a 3-vessel CABG he underwent 2 weeks prior when he develops abdominal pain with distension and obstipation. His heart rate is 115 bpm and his laboratory test results are notable for a WBC of 15 and potassium of 2.6. He is on a scheduled narcotic regimen prescribed by pain medicine for chronic back pain and ciprofloxacin for a UTI. He denies any history of melena and states his last screening colonoscopy was 4 months ago, which was normal. An obstructive series is ordered demonstrating the following findings:
What is the next BEST step in the management of this patient?A. Administer neostigmine with atropine available as needed
Correct Answer: B
This patient has imaging findings concerning for a large bowel obstruction that is most likely caused by a sigmoid volvulus as seen by the presence of an inverted U-shaped colon that is distended and extending from the pelvis to the right upper quadrant along with paucity of air in the rectum. Abdominal radiographs can only diagnose sigmoid volvulus in 60% of cases and usually require CT imaging or contrast enema. The most appropriate next step requires CT of the abdomen/pelvis and surgical consultation. CT is useful to rule out other causes of obstruction such as a tumor, impacted stool, or foreign body. The management of sigmoid volvulus requires sigmoidoscopy to evaluate the mucosa, and if no signs of ischemia are present, the next step would be an attempt at endoscopic detorsion with elective sigmoidectomy, as there is a 60% recurrence rate of nonsurgical management. If the mucosa is ischemic the patient would require an emergent sigmoidectomy. The patient’s age and history of recent antibiotic exposure places him at risk of C. difficile colitis and toxic megacolon, and occasionally C. difficile colitis presents with ileus but empiric treatment without a positive stool sample is unlikely to improve the patient’s symptoms. Nasogastric tubes function even in large bowel obstructions independent of a competent ileocecal valve but serial abdominal examinations would lead to perforated sigmoid colon in this patient. The obstructive series shows no significant stool burden, and constipation is unlikely to be driving this process. Intestinal pseudoobstruction (Ogilvie syndrome) is a diagnosis of exclusion and usually involves dilation of the entire colon. It is more common in cardiac surgery patients and supportive care including correction of electrolytes, especially hypokalemia, and avoidance of narcotics are beneficial. Neostigmine can be used for treatment of patients refractory to supportive care. However, neostigmine can cause significant bradycardia (which can be treated with atropine), and thus needs to be administered in a monitored setting. However, a mechanical obstruction must be ruled out before administration of neostigmine, as this can lead to proximal colonic perforation. Further management includes colonic decompression.