Constipation Diagnosis and Management

Initial Assessment

The American Gastroenterological Association recommends beginning with a detailed digital rectal examination that includes assessment of pelvic floor motion during simulated evacuation, before ordering any imaging or specialized testing 1, 2
A thorough medical history should include bowel pattern specifics, such as date of last defecation, frequency, stool consistency, and recent changes, as well as the presence or absence of urge to defecate and sensation of complete evacuation, according to the Annals of Oncology 3
The initial evaluation should also assess for red flag symptoms, including blood in stool, mucus, need for digital manipulation to evacuate, and fecal incontinence, as suggested by the Annals of Oncology 3
A medication review should be conducted to identify potential contributing factors, including opiates, anticholinergics, and calcium channel blockers, as recommended by Gastroenterology 1, 2
Lifestyle factors, such as eating and drinking habits, physical activity level, and privacy for defecation, should be evaluated, according to the Annals of Oncology 3
Comorbidities, including pre-existing irritable bowel syndrome, diverticular disease, heart failure, and chronic pulmonary disease, should be assessed, as suggested by the Annals of Oncology 3

The digital rectal examination must assess resting sphincter tone and squeeze augmentation, as recommended by Gastroenterology 1, 2
The examination should also evaluate puborectalis muscle contraction during squeeze, perineal descent during simulated evacuation, and the presence of impacted feces, hemorrhoids, masses, or stenosis, according to Gastroenterology 2 and the Annals of Oncology 3
The patient's ability to "expel my finger" during simulated defecation should be assessed, as suggested by Gastroenterology 2
Abdominal examination should evaluate distension, masses, liver enlargement, tenderness, and bowel sounds, according to the Annals of Oncology 3
Perineal inspection should check for skin tags, fissures, prolapse, anal warts, and perianal ulceration, as recommended by the Annals of Oncology 3

The American Gastroenterological Association recommends ordering only a complete blood count in the absence of other symptoms, as this is the single necessary test 1, 4
Metabolic panels, including glucose, calcium, and thyroid-stimulating hormone, should not be routinely ordered unless specific clinical features warrant them, as suggested by Gastroenterology 1, 4
Corrected calcium and thyroid function should only be checked if clinically suspected based on other symptoms, according to the Annals of Oncology 3

Colonoscopy is indicated only if alarm symptoms are present, such as blood in stool, anemia, or weight loss, or if there is an abrupt onset of constipation, or if the patient is over 50 years old without previous colorectal cancer screening, as recommended by Gastroenterology 1, 4
The American Gastroenterological Association suggests that colonoscopy provides direct visualization and biopsy capability, making it the first-line imaging option 4
Alternatives to colonoscopy include CT colonography, flexible sigmoidoscopy combined with barium enema, but plain abdominal radiographs should be avoided due to limited utility, according to Gastroenterology 1, 4

Specialized functional tests, such as colonic transit studies and anorectal function tests, should only be ordered after a trial of fiber supplementation and over-the-counter laxatives, and if the initial evaluation suggests defecatory disorder or slow-transit constipation, as recommended by Gastroenterology 1
Colonic transit studies are indicated for persistent symptoms despite treatment, or when anorectal tests do not show defecatory disorder, according to Gastroenterology 1, 4
Anorectal manometry is indicated when digital rectal examination suggests pelvic floor dysfunction, or if the patient reports prolonged straining, need for perineal/vaginal pressure to evacuate, or digital evacuation of stool, as suggested by Gastroenterology 1, 2

The Bowel Function Index (BFI) should be used as a validated tool for assessing constipation severity, particularly for opioid-induced constipation, as recommended by the Annals of Oncology 3, 5
Medication should be considered for BFI score ≥30 points with no response to initial laxatives, according to the Annals of Oncology 3

The American Gastroenterological Association recommends not relying solely on digital rectal examination to exclude defecatory disorders, as a normal exam does not rule them out 1, 2
Excessive metabolic testing without clinical indication should be avoided, as it increases costs without proven benefit, according to Gastroenterology 1, 4
Structural evaluation should not be skipped in high-risk patients, such as those with alarm symptoms, age >50 without screening, or abrupt onset, as recommended by Gastroenterology 1, 4
Specialized testing should not be proceeded to before attempting empiric fiber/laxative trial, according to Gastroenterology 1

The American Society of Clinical Oncology recommends checking corrected calcium levels and thyroid function tests only if clinically suspected based on other symptoms 6, 7
Plain abdominal X-ray has limited utility as a standalone tool, but may be useful to image the extent of fecal loading and exclude bowel obstruction 8, 7
Enemas are contraindicated in patients with paralytic ileus or intestinal obstruction, severe colitis, inflammation, or infection of the abdomen 8, 7

The American Gastroenterological Association recommends avoiding bulk laxatives (psyllium) for opioid-induced constipation 8, 7
Magnesium and sulfate salts should be used cautiously in renal impairment due to risk of hypermagnesemia 8, 7

A thorough medical history must elicit specific bowel pattern details, including date of last defecation, frequency, and stool consistency, and assess for contributing factors such as medication review and physical activity level 6
The American College of Gastroenterology recommends using the Bowel Function Index (BFI) as a validated tool for assessing constipation severity, particularly for opioid-induced constipation 6

The European Society for Medical Oncology recommends ensuring privacy and comfort for defecation, positioning, increasing fluid intake, and increasing activity and mobility within patient limits as first-line prevention strategies 8, 7
Osmotic laxatives, such as PEG (17g/day), are preferred first-line options for pharmacologic therapy 8, 7
For elderly patients, PEG (17g/day) offers efficacy with a good safety profile 8, 7
Unless contraindicated by pre-existing diarrhea, all patients receiving opioid analgesics should be prescribed a concomitant laxative prophylactically 8, 7
Combined opiate/naloxone medications reduce opioid-induced constipation risk 8, 7
For unresolved opioid-induced constipation, peripherally acting μ-opioid receptor antagonists (PAMORAs) may be valuable 8, 7
Avoid liquid paraffin for bed-bound patients and those with swallowing disorders 8