How to manage postoperative constipation?

Management of Postoperative Constipation

A multifaceted approach to preventing and treating postoperative constipation should include optimized fluid management, early mobilization, early oral intake, laxative administration, and minimization of constipating medications.

Assessment and Prevention

• Rule out impaction or obstruction through physical examination and abdominal x-ray if needed 1
• Discontinue any non-essential constipating medications, particularly opioids 1, 2
• Treat other potential causes of constipation such as hypercalcemia, hypokalemia, hypothyroidism, or diabetes mellitus 1
• Optimize fluid management by avoiding overhydration while ensuring adequate hydration (aim for weight gain <3 kg by postoperative day 3) 1
• Implement opioid-sparing analgesia techniques to reduce constipation risk 1, 2
• Remove nasogastric tubes as early as possible 1

Dietary and Lifestyle Interventions

• Encourage early oral intake with small portions initially, especially after right-sided resections and small-bowel anastomosis 1
• Increase fluid intake to maintain adequate hydration (≥1.5 L/day) 1, 3
• Increase dietary fiber if patient has adequate fluid intake and physical activity 1, 3
• Encourage early mobilization as soon as the patient's condition allows 1
• Consider a bland/BRAT diet (Bananas, Rice, Applesauce, Toast) initially if there are concerns about diarrhea 1

Pharmacological Management

First-line options:

• Bisacodyl 10-15 mg daily to TID with a goal of one non-forced bowel movement every 1-2 days 1, 4
• Polyethylene glycol (1 capful/8 oz water BID), which generally produces a bowel movement in 1-3 days 1, 5

Second-line options:

• Bisacodyl suppository (one rectally daily-BID) 1
• Lactulose 30-60 mL BID-QID 1
• Sorbitol 30 mL every 2 hours x 3, then as needed 1
• Magnesium hydroxide 30-60 mL daily-BID 1
• Magnesium citrate 8 oz daily 1

For severe cases:

• Glycerine suppository with or without mineral oil retention enema 1
• Consider methylnaltrexone for opioid-induced constipation (0.15 mg/kg SC every other day, no more than once a day), except in cases of post-op ileus and mechanical bowel obstruction 1, 6
• Consider prokinetic agents such as metoclopramide (10-20 mg PO QID) 1
• Water-soluble contrast agents and neostigmine may be considered for treating persistent postoperative ileus 1

Special Considerations

• If constipation persists despite first-line measures, perform manual disimpaction following pre-medication with analgesic and anxiolytic 1
• For persistent ileus, consider tap water enema until clear 1
• Discontinue laxatives if diarrhea develops 5
• Do not use laxatives for more than one week without medical supervision 4, 5
• Patients with longer operation times, higher blood loss, and higher postoperative morphine doses are at increased risk for constipation and may require more aggressive prevention 2

Monitoring

• Reassess for cause and severity of constipation if initial interventions are ineffective 1
• Monitor for signs of rectal bleeding, worsening abdominal pain, bloating, or cramping which may indicate a serious condition 4, 5
• Continue to treat and monitor symptoms and quality of life with ongoing reassessment 1