What is the appropriate management for a patient presenting with no bowel movement (constipation) and abdominal pain?

Management of Constipation with Abdominal Pain

Immediate Priority: Rule Out Bowel Obstruction

The first and most critical step is to determine whether this represents a mechanical bowel obstruction requiring urgent surgical evaluation, versus functional constipation that can be managed conservatively. 1, 2

Clinical Assessment to Differentiate Obstruction from Functional Constipation

History findings suggesting mechanical obstruction:

• Intermittent colicky abdominal pain that worsens after eating 1
• Regular vomiting (green/yellow if proximal, feculent if distal obstruction) 1, 2
• Absolute constipation (no passage of stool or gas) 2
• Previous abdominal surgeries (adhesions cause 55-75% of small bowel obstructions) 1
• Sudden onset of severe, maximally intense pain 3

Physical examination findings suggesting obstruction:

• Abdominal distention with visible peristalsis 1
• High-pitched or absent bowel sounds 4
• Severe direct tenderness, involuntary guarding, rigidity, or rebound tenderness (suggests advanced obstruction or perforation) 4
• Signs of dehydration or sepsis: tachycardia, fever, hypotension, dry mucous membranes 4

Laboratory red flags for obstruction:

• Marked leukocytosis with bandemia 4
• Elevated lactate (suggests bowel ischemia, though ischemia can occur without hyperlactatemia) 1
• Electrolyte abnormalities from vomiting and dehydration 1

Immediate Diagnostic Imaging

Obtain CT abdomen/pelvis with IV contrast immediately if obstruction is suspected. 1, 2 This is the gold standard for:

• Confirming mechanical obstruction versus functional ileus 2, 4
• Identifying transition point between dilated and normal bowel 1
• Detecting complications: perforation, ischemia, closed-loop obstruction 1
• Distinguishing complete from partial obstruction 2

Management Algorithm Based on Diagnosis

If Complete Mechanical Obstruction Confirmed

Immediate surgical consultation is mandatory. 2, 3

Medical resuscitation while awaiting surgery: 4

• NPO (nothing by mouth) 4
• Aggressive IV fluid resuscitation 4
• Nasogastric tube decompression 4
• IV broad-spectrum antibiotics 4
• Correct electrolyte abnormalities 4

Do NOT use prokinetic agents (metoclopramide) in complete obstruction—they can cause perforation. 2

Surgery is required for: 4

• Complete obstruction not resolving with conservative management
• Signs of bowel perforation, ischemia, or necrosis
• Clinical deterioration despite medical therapy

If Partial Obstruction Without Ischemia

Trial of non-operative management is appropriate. 2

• NPO with IV hydration 4
• Nasogastric decompression 4
• Water-soluble contrast (gastrografin) is both diagnostic and therapeutic 2
• Serial abdominal exams and labs to monitor for deterioration 4

Proceed to surgery if: 2

• Evidence of strangulation develops
• Failure to resolve with 48-72 hours of adequate decompression
• Clinical deterioration

If Functional Constipation (No Obstruction on Imaging)

Conservative management is appropriate, but identify and treat reversible causes first. 2

Medication Review

Stop or reduce opioids if possible—they are a common cause of constipation with abdominal pain. 1

• Opioid-induced bowel dysfunction causes constipation and worsening abdominal pain 1
• Consider peripheral mu-opioid antagonists (naloxone, methylnaltrexone) if opioids cannot be stopped 1
• Avoid cyclizine long-term (anticholinergic effects worsen constipation) 1

Review other constipating medications: 2

• Anticholinergics, calcium channel blockers, antidepressants 1

Correct Metabolic Abnormalities

• Electrolyte disturbances (hypokalemia, hypercalcemia) 2
• Hypothyroidism 2

Dietary and Lifestyle Modifications

First-line treatment: 5

• Small, frequent meals 5
• Adequate hydration 5
• Avoid high-fat foods 5
• Regular exercise 1

Soluble fiber supplementation (ispaghula 3-4g/day, titrated gradually) is effective for constipation and abdominal pain, but avoid insoluble fiber (wheat bran) which worsens symptoms. 1, 5

Pharmacologic Management

For constipation without alarm features, laxatives are appropriate: 1

• Polyethylene glycol (osmotic laxative) is first-line 6
• Loperamide should NOT be used (worsens constipation) 1

Stop laxatives and seek urgent evaluation if: 6

• Rectal bleeding develops
• Nausea, bloating, cramping, or abdominal pain worsens
• Diarrhea develops (may indicate obstruction resolving or overflow)

For abdominal pain with constipation: 5

• Antispasmodics (dicyclomine, hyoscyamine, peppermint oil) as first-line 5
• Tricyclic antidepressants (amitriptyline 10mg, titrated to 30-50mg) as second-line for refractory pain 1, 5

Red Flags Requiring Urgent Referral

Refer immediately to gastroenterology or surgery if: 5

• Age >50 with new-onset symptoms 5
• Weight loss, nocturnal symptoms, rectal bleeding 5
• Family history of GI malignancy or inflammatory bowel disease 5
• Failure to respond to first-line therapies within 8-12 weeks 5
• Alarm features on imaging 5

Common Pitfalls to Avoid

Do not assume functional constipation in patients with prior abdominal surgery—adhesive obstruction is often missed because imaging may not show a clear transition point if bowel is fixed by adhesions. 1 Obtain CT during an episode of severe pain for best diagnostic yield. 1

Do not use prokinetics in suspected obstruction—they increase perforation risk. 2

Do not overlook narcotic bowel syndrome in chronic opioid users—escalating opioids worsens pain through hyperalgesia. 1 Treatment requires opioid reduction, not escalation. 1

Do not delay imaging in elderly patients or those with vascular risk factors—mesenteric ischemia presents with pain out of proportion to exam and requires urgent intervention. 7