Management of Constipation in Patients with an Abnormally Long Colon

Initial Assessment and Evaluation

The American Gastroenterological Association recommends starting with lifestyle modifications, including increased fluids and exercise, then initiating osmotic laxatives (polyethylene glycol 17g daily) as first-line pharmacologic therapy, escalating to stimulant laxatives (bisacodyl 10-15mg daily) if needed, while ruling out fecal impaction and mechanical obstruction through digital rectal examination 1, 2
A careful digital rectal examination should be conducted to assess pelvic floor motion during simulated evacuation and identify fecal impaction or defecatory disorders 3, 2
Mechanical obstruction should be ruled out through physical examination and abdominal x-ray if clinically indicated, as recommended by the National Comprehensive Cancer Network 4, 5
Non-essential constipating medications, such as anticholinergics, opioids, and antacids, should be discontinued whenever feasible, according to the National Comprehensive Cancer Network 5, 6
A complete blood count should be obtained as the only routine laboratory test needed in the absence of alarm symptoms, as suggested by the American Gastroenterological Association 3, 2

The American Gastroenterological Association recommends initiating polyethylene glycol (PEG) 17g once daily as the preferred first-line pharmacologic agent, with moderate-quality evidence for increasing complete spontaneous bowel movements (mean difference 2.90 per week) and durable response over 6 months 1
Fluid intake should be increased to adequate levels, particularly in patients with low baseline fluid consumption, as recommended by the American Gastroenterological Association 1
Physical activity should be encouraged when appropriate, though evidence for its effectiveness is limited, according to the National Comprehensive Cancer Network 4, 5

Bisacodyl 10-15mg daily should be added to three times daily, with a goal of one non-forced bowel movement every 1-2 days, as recommended by the National Comprehensive Cancer Network 4, 5, 6
Alternative stimulant options include senna (2-3 tablets BID-TID) or glycerol suppositories, according to the National Comprehensive Cancer Network 4, 2

Lactulose 30-60mL BID-QID or sorbitol can be used as osmotic alternatives, as recommended by the National Comprehensive Cancer Network 4, 5, 7
Prokinetic agents, such as metoclopramide 10-20mg PO QID, can be used if gastroparesis is suspected, according to the National Comprehensive Cancer Network 4, 5, 7

Glycerine suppository ± mineral oil retention enema should be administered if digital rectal examination identifies impaction, as recommended by the National Comprehensive Cancer Network 4, 5
Manual disimpaction should be performed following premedication with analgesic ± anxiolytic, according to the National Comprehensive Cancer Network 4, 5
Tap water enema should be used until clear if needed, as recommended by the National Comprehensive Cancer Network 4, 5

Stimulant laxatives, such as senna ± docusate, should be prescribed prophylactically when initiating opioids, as recommended by the Annals of Oncology 8, 6
Bulk laxatives should be avoided as they are ineffective for opioid-induced constipation, according to the National Comprehensive Cancer Network 6, 7
Methylnaltrexone 0.15mg/kg subcutaneously every other day (maximum once daily) can be considered for refractory opioid-induced constipation, except in postoperative ileus or mechanical obstruction, as recommended by the National Comprehensive Cancer Network 4, 5, 6, 7

Patients with persistent symptoms despite adequate medical therapy or severe obstructed defecation should be referred for anorectal physiology testing and colonic transit studies, as recommended by the American Gastroenterological Association 2