What is the appropriate workup for a patient who has not had a bowel movement for 10 days?

Workup for 10 Days Without a Bowel Movement

A patient who has not had a bowel movement for 10 days requires immediate assessment for fecal impaction and bowel obstruction, followed by targeted testing only if alarm features are present.

Immediate Clinical Assessment

Digital Rectal Examination (Essential First Step)

• Perform a thorough digital rectal examination to rule out fecal impaction, which is the most urgent concern after 10 days without defecation 1.
• Assess for hard stool in the rectal vault, which indicates impaction requiring immediate disimpaction 1.
• Evaluate pelvic floor motion during simulated evacuation (ask patient to "bear down" and "squeeze") to detect dyssynergic defecation 1.
• Check for perianal soiling, anal tone, and puborectalis muscle function 1.

Physical Examination for Obstruction

• Perform abdominal examination and obtain an abdominal X-ray to rule out mechanical bowel obstruction, especially if the patient has abdominal distension, severe pain, or systemic toxicity 1.
• CT imaging is preferable to plain X-ray if perforation or severe complications are suspected 1.

Laboratory Testing (Minimal and Targeted)

Basic Blood Work

• Obtain only a complete blood count (CBC) as the sole routine test 1.
• The American Gastroenterological Association specifically recommends against routine metabolic panels (thyroid-stimulating hormone, glucose, calcium) unless other clinical features warrant them, as their diagnostic yield is extremely low 1.

When to Expand Testing

• Order metabolic tests (TSH, calcium, glucose, creatinine) only if specific symptoms suggest secondary causes: unexplained weight changes, polyuria, muscle weakness, or other systemic symptoms 1.

Alarm Features Requiring Further Investigation

Red Flags That Mandate Colonoscopy

• Age >50 years without prior colorectal cancer screening 1.
• Acute onset of constipation (sudden change from normal bowel habits) 1.
• Rectal bleeding, unexplained anemia, or unintentional weight loss 1, 2.
• Family history of colorectal cancer or inflammatory bowel disease 2.

When Colonoscopy Is NOT Needed

• Do not perform colonoscopy in patients without alarm features, even with chronic constipation 1.
• Young patients (<50 years) with gradual onset constipation and no red flags do not require structural evaluation 1, 2.

Medication Review (Critical Step)

• Discontinue or adjust constipating medications before further testing, if clinically feasible 1.
• Common culprits include opioids, anticholinergics, calcium channel blockers, iron supplements, and antacids containing aluminum or calcium 3, 4.

Specialized Testing (Only After Initial Management Fails)

Anorectal Manometry and Balloon Expulsion Test

• Reserve anorectal testing for patients who fail empiric laxative therapy, not as initial workup 1, 5.
• These tests identify defecatory disorders (dyssynergic defecation) that may respond to biofeedback therapy 4, 5.

Colonic Transit Study

• Perform colonic transit testing only if symptoms persist despite adequate laxative therapy and normal anorectal testing 1, 5.
• This identifies slow-transit constipation, which may require different management 4, 5.

Common Pitfalls to Avoid

• Do not order extensive metabolic panels routinely—the American Gastroenterological Association explicitly recommends against this due to low yield and poor cost-effectiveness 1.
• Do not skip the digital rectal examination—it is the single most important diagnostic maneuver and must include assessment of pelvic floor motion, not just a cursory check 1.
• Do not assume testing is needed before treatment—most patients should receive empiric laxative therapy first, with testing reserved for non-responders 1, 3.
• Do not confuse patient-reported "constipation" with medical definitions—patients often describe bloating, straining, and incomplete evacuation rather than infrequent stools, so clarify their specific symptoms 3.

Immediate Management While Completing Workup

If impaction is confirmed on digital examination:

• Administer glycerin suppository ± mineral oil retention enema 1.
• Perform manual disimpaction with pre-medication (analgesic ± anxiolytic) if needed 1.
• Follow with aggressive oral laxative regimen: bisacodyl 10-15 mg daily, polyethylene glycol 17g twice daily, and consider lactulose 30-60 mL twice daily 1, 6.

If no impaction but severe constipation:

• Start bisacodyl 10-15 mg daily plus polyethylene glycol (MiraLAX) 17g in 8 oz water twice daily with goal of one non-forced bowel movement every 1-2 days 1, 6.
• Ensure adequate hydration (at least 64 oz daily), as polyethylene glycol requires fluid to work effectively 6.