Do you always offer colonoscopy (examination of the colon using a flexible tube with a camera) for patients with new onset constipation?

Colonoscopy for New-Onset Constipation

Colonoscopy should NOT be routinely performed for new-onset constipation unless the patient has alarm features (blood in stools, anemia, unexplained weight loss), abrupt onset, age >50 without prior colorectal cancer screening, or family history of early colorectal cancer. 1

Risk Stratification Approach

Patients Who DO Require Colonoscopy

Perform colonoscopy if ANY of the following are present:

• Age >50 years without prior age-appropriate colorectal cancer screening 1, 2
• Alarm features: rectal bleeding, iron deficiency anemia, or unexplained weight loss (>5 kg) 1, 2
• Abrupt onset of constipation (suggests possible mechanical obstruction) 1
• Family history of colorectal cancer in first-degree relative diagnosed <50 years old 1
• Palpable abdominal or rectal mass on examination 2

The 2023 DIRECT guidelines emphasize that hematochezia, unexplained iron deficiency anemia, and unexplained weight loss confer a hazard ratio of approximately 10-fold for early-onset colorectal cancer, making colonoscopy mandatory in these scenarios. 1 Optimally, colonoscopy should be performed within 30 days when alarm symptoms are present. 1

Patients Who Do NOT Require Colonoscopy

The American Gastroenterological Association explicitly states colonoscopy should NOT be performed in patients without alarm features unless age-appropriate screening has not been done. 1, 3, 4

For isolated new-onset constipation in patients without the above risk factors:

• Complete blood count is the only routinely necessary test 1, 4
• Metabolic testing (thyroid, calcium, glucose) is NOT recommended unless other clinical features suggest these disorders 1, 4
• Digital rectal examination with assessment of pelvic floor motion during simulated evacuation should be performed 1, 4

Initial Management Before Considering Colonoscopy

For patients without alarm features, empiric treatment should be attempted first:

• Trial of fiber supplementation and over-the-counter laxatives for 1-2 weeks 1, 4
• Discontinue constipating medications if feasible 1
• Lifestyle modifications including adequate fluid intake and physical activity 5, 6

Specialized testing (anorectal manometry, colonic transit studies) should only be considered after failed empiric therapy, NOT before. 1, 4

Special Consideration: Change in Bowel Habits vs. Isolated Constipation

The 2023 DIRECT guidelines note that while abdominal pain and changes in bowel habits are common presenting symptoms of early-onset colorectal cancer, these symptoms are non-specific and endoscopic evaluation is NOT recommended for all young adults with these symptoms alone. 1 The decision should be individualized based on:

• Presence of other alarm symptoms 1
• Colorectal cancer risk factors 1
• Duration and severity of symptoms 1

Common Pitfalls to Avoid

Do not reflexively order colonoscopy for every patient with new constipation. This represents overutilization of resources and exposes patients to unnecessary procedural risks. 1, 3 The American Gastroenterological Association provides strong recommendations (with moderate-quality evidence) against this practice. 1

Do not skip the digital rectal examination. While a normal examination does not exclude defecatory disorders, it provides critical information about pelvic floor dysfunction and can guide further management without invasive testing. 1, 4

Do not order extensive metabolic panels routinely. Their diagnostic utility and cost-effectiveness are low in the absence of other clinical features suggesting specific endocrine or metabolic disorders. 1, 4