What is the recommended bowel regimen for managing fecal impaction?

Bowel Regimen for Fecal Impaction

For fecal impaction, perform manual disimpaction with pre-medication (analgesic ± anxiolytic), followed immediately by enemas (glycerine suppository ± mineral oil retention enema or tap water enema), then initiate oral polyethylene glycol (PEG) with a maintenance laxative regimen to prevent recurrence. 1

Immediate Management Algorithm

Step 1: Confirm Diagnosis and Rule Out Contraindications

• Perform digital rectal examination (DRE) to identify the large mass of dry, hard stool in the rectum 2, 1
• Critical caveat: If impaction is in the proximal rectum or sigmoid colon, DRE may be non-diagnostic and you'll need imaging (abdominal x-ray or CT) 2
• Rule out absolute contraindications before proceeding: neutropenia (WBC < 0.5 cells/μL), thrombocytopenia, paralytic ileus, intestinal obstruction, recent colorectal/gynecological surgery, recent anal/rectal trauma, severe colitis, toxic megacolon, undiagnosed abdominal pain, or recent pelvic radiotherapy 2, 1

Step 2: Distal Fecal Impaction Treatment (Rectum)

• Pre-medicate with analgesics ± anxiolytics before the procedure to prevent vagal stimulation and potential bradycardic arrest 2, 1
• Perform manual disimpaction: Digital fragmentation and extraction of the stool mass 2, 1
• Follow immediately with enemas to facilitate passage of remaining stool 2:
  • Glycerine suppository ± mineral oil retention enema (warm oil: cottonseed, arachis, or olive oil) 2
  • Alternative options: hypertonic sodium phosphate enema, docusate sodium enema, or bisacodyl enema 2
  • Tap water enema until clear if needed 2

Step 3: Proximal Fecal Impaction Treatment (Sigmoid/Proximal Colon)

• Once distal colon is partially emptied, administer oral PEG solutions containing electrolytes to soften or wash out proximal stool 2, 1
• Dosing: PEG 1 capful (17g) in 8 oz water twice daily 2
• In absence of complete bowel obstruction, this lavage approach is the primary treatment for proximal impaction 2, 1

Step 4: Adjunctive Laxatives (If Initial Treatment Insufficient)

Consider adding these agents sequentially if impaction persists 2:

• Bisacodyl suppository (one rectally daily-BID) 2
• Lactulose 30-60 mL BID-QID 2
• Sorbitol 30 mL every 2 hours × 3, then PRN 2
• Magnesium hydroxide 30-60 mL daily-BID (use cautiously in renal impairment due to hypermagnesemia risk) 2
• Magnesium citrate 8 oz daily 2
• Metoclopramide 10-20 mg PO QID as a prokinetic agent 2

Maintenance Bowel Regimen (Critical to Prevent Recurrence)

Implement immediately after successful disimpaction 1:

First-Line Maintenance Laxatives

• Osmotic laxatives (preferred): PEG 17g daily, lactulose, or magnesium salts 2, 1
• Stimulant laxatives: Senna, cascara, bisacodyl, or sodium picosulfate 2, 1
• Titrate bisacodyl 10-15 mg daily-TID with goal of 1 non-forced bowel movement every 1-2 days 2

Laxatives to AVOID

• Do not use bulk laxatives (psyllium) in patients with opioid-induced constipation or limited mobility 2, 1

Non-Pharmacologic Measures

• Increase daily water intake 2, 1
• Increase dietary fiber to 30 g/day if patient has adequate fluid intake and physical activity 2, 3
• Discontinue non-essential constipating medications 2
• Educate patients to attempt defecation at least twice daily, usually 30 minutes after meals 1

Special Populations

Opioid-Induced Constipation

• All patients on opioids should receive prophylactic laxatives (osmotic or stimulant preferred) 2
• If standard laxatives fail, consider peripheral opioid antagonists: methylnaltrexone 0.15 mg/kg subcutaneously every other day (contraindicated in post-op ileus and mechanical obstruction) 2
• Combined opioid/naloxone medications reduce OIC risk 2

Elderly Patients

• Higher risk population requiring particular attention 1
• PEG 17g/day offers efficacious and tolerable solution with good safety profile 1
• Ensure toilet access for patients with decreased mobility 1

Common Pitfalls to Avoid

• Never skip pre-medication before manual disimpaction—vagal stimulation can cause bradycardia and hemodynamic instability 1, 3
• Don't use enemas in neutropenic patients (WBC < 0.5)—risk of sepsis is prohibitive 2, 1
• Don't assume DRE rules out impaction—proximal impactions require imaging 2, 1
• Don't forget maintenance therapy—recurrence is extremely common without preventive measures 1, 3
• Watch for overflow diarrhea—watery stool leaking around impaction can be mistaken for diarrhea, delaying diagnosis 2

When to Escalate Care

• Surgical resection is reserved for complications: stercoral ulceration, perforation, or peritonitis 2, 4, 3
• Consider endoscopic intervention for severe cases unresponsive to medical therapy 5, 3
• Post-treatment colonic evaluation (flexible sigmoidoscopy, colonoscopy, or barium enema) should be performed after impaction resolves to identify underlying causes 5