Shoulder Pain Associated with Constipation: Evaluation and Management
Direct Answer
Shoulder pain associated with constipation most likely represents referred pain from diaphragmatic irritation due to severe fecal impaction causing colonic distension, bowel obstruction, or in rare cases, perforation with peritonitis—this is a potentially serious condition requiring immediate evaluation to exclude life-threatening complications. 1, 2
Pathophysiology of Referred Shoulder Pain
- Diaphragmatic irritation from intra-abdominal pathology causes referred pain to the shoulder via the phrenic nerve (C3-C5 nerve roots), which shares the same dermatome as the shoulder. 3
- In the context of severe constipation or fecal impaction, colonic distension can irritate the diaphragm, particularly when the transverse or splenic flexure is involved. 1, 2
- Referred shoulder pain preceding or accompanying abdominal symptoms is an important warning sign of serious intra-abdominal illness, including perforation and peritonitis. 3
Immediate Assessment Required
Red Flag Symptoms to Evaluate
- Assess for signs of bowel obstruction: absolute constipation (no passage of stool or flatus), abdominal distension, vomiting, and colicky abdominal pain worsening after oral intake. 4
- Evaluate for peritoneal signs: severe abdominal pain, rigidity, guarding, rebound tenderness, and hemodynamic instability suggesting perforation. 1, 2
- Document the temporal relationship: shoulder pain that precedes abdominal pain by hours is particularly concerning for serious pathology. 3
- Obtain vital signs to assess for tachycardia, hypotension, or fever indicating systemic complications. 2
Physical Examination Priorities
- Perform abdominal examination evaluating for distension, masses, tenderness, rigidity, and bowel sounds (absent sounds suggest ileus or obstruction). 5
- Conduct digital rectal examination to assess for fecal impaction, which is palpable as a hard mass in the rectum. 5, 6
- Examine the shoulder itself to exclude intrinsic shoulder pathology (though this is less likely given the temporal association with constipation). 7
Diagnostic Workup
Imaging Studies
- Order an acute abdominal series (plain radiographs) immediately to assess for fecal loading, bowel obstruction, and free air under the diaphragm indicating perforation. 6, 1, 2
- If plain films are inconclusive or clinical suspicion remains high, obtain CT abdomen/pelvis to identify the extent of impaction, bowel wall integrity, and exclude perforation or stercoral ulceration. 2
- Plain abdominal X-ray is useful to image the extent of fecal loading and exclude bowel obstruction, though it has limited utility as a standalone tool. 5
Laboratory Testing
- Obtain complete blood count to assess for leukocytosis suggesting infection or perforation. 5
- Check metabolic panel including electrolytes, as severe constipation can cause metabolic derangements. 5
Treatment Algorithm
If Bowel Obstruction or Perforation Suspected
- Immediate surgical consultation is mandatory for signs of complete intestinal obstruction (absolute constipation, severe pain, distension, vomiting) or peritonitis. 4, 1, 2
- Make the patient NPO (nothing by mouth), place nasogastric tube for decompression if vomiting, initiate IV fluids, and obtain urgent imaging. 2
- Surgical resection of involved colon or rectum is reserved for cases complicated by perforation and peritonitis. 1, 2
If Fecal Impaction Without Obstruction
- Manual disimpaction or fragmentation is the first-line treatment for rectal fecal impaction. 6, 1, 2
- Administer distal softening with oil retention enema followed by oral polyethylene glycol (PEG) solution via mouth or nasogastric tube. 6, 2
- Use rectal lavage with sigmoidoscopic assistance or water-soluble contrast media (Gastrografin) to identify extent and aid in removal. 2
- Avoid enemas if paralytic ileus, complete obstruction, severe colitis, or perforation is suspected. 5
Post-Acute Management
- After resolution of impaction, perform colonic evaluation with flexible sigmoidoscopy, colonoscopy, or barium enema to exclude structural pathology (stricture, mass, diverticular disease). 6, 1
- Initiate preventive therapy with PEG 17 grams daily as first-line maintenance laxative. 8, 5
- Increase dietary fiber to 30 grams/day and water intake to prevent recurrence. 1, 2
- Discontinue constipating medications if feasible (opioids, anticholinergics, calcium channel blockers). 5
Critical Pitfalls to Avoid
- Do not dismiss shoulder pain as musculoskeletal without thoroughly evaluating for intra-abdominal pathology when constipation is present. 3
- Do not delay imaging in patients with severe constipation and referred shoulder pain, as this combination suggests serious complications. 1, 2
- Do not use bulk laxatives (psyllium) or stimulant laxatives in the setting of suspected bowel obstruction, as they can worsen the condition. 5
- Do not perform aggressive enema administration if complete obstruction is suspected, as this increases perforation risk. 5, 2
- Do not assume the shoulder pain is from hemiplegic shoulder pathology (as in stroke patients) without first excluding acute abdominal emergencies. 4
Special Considerations
High-Risk Populations
- Elderly, institutionalized, and incapacitated patients are at highest risk for fecal impaction and its complications. 2
- Patients on chronic opioid therapy require prophylactic laxatives from the start of opioid use to prevent severe constipation. 4, 5
When Shoulder Pain Persists After Constipation Resolution
- If shoulder pain continues after successful treatment of constipation, then evaluate for intrinsic shoulder pathology including rotator cuff injury, impingement, or cervical spine disorders. 7
- Consider that chronic constipation may have been coincidental rather than causative if shoulder examination reveals primary shoulder pathology. 7