Diarrhea
Common Causes:
- Iatrogenic: Antibiotics, chemotherapy, radiation therapy
- Partial obstruction/impaction (overflow)
- Pancreatic insufficiency
- Infections, HIV/AIDS, secretory diarrhea (chemo-related)
Treatment Strategies:
- Bulk-forming agents: Psyllium
- Anti-motility agents: Loperamide, diphenoxylate/atropine, tincture of opium
- Others: Octreotide, pancreatic enzyme replacement, antimicrobials (if infectious)
Constipation
Etiologies:
- Neurogenic: DM, MS, SCI, Parkinson’s
- Non-neurogenic: Hypothyroidism, hypokalemia, slow transit, pregnancy
- Dietary/Behavioral: Low fiber, dehydration
- Medication-induced: Opioids, antihistamines, antispasmodics, antipsychotics, iron, calcium, aluminum, vinca alkaloids, CCBs, 5HT3 antagonists
Treatment Principles:
- Address reversible causes (hydration, diet, medications)
- Use stool softeners, stimulants, and osmotic agents depending on symptom severity and functional status
- Opioid-induced constipation requires agents targeting gut motility and secretion (e.g., PAMORAs)
Malignant Bowel Obstruction (MBO)
Clinical Presentation:
- Near-universal nausea (90-100%)
- Vomiting (87–100%)
- Colicky abdominal pain (72–80%)
- Absent bowel movements/flatus >72 hrs in 85–93%
- Note: Lack of symptoms may indicate ileus rather than mechanical obstruction
Treatment Considerations:
- Differentiate mechanical vs. functional ileus
- First-line: NG tube decompression, antiemetics, corticosteroids, and bowel rest
- Second-line: Octreotide, anticholinergics, or procedural interventions (paracentesis if ascites is contributing)
Key Takeaway:
Bowel symptoms in palliative care are multifactorial. Early identification of etiology and tailored pharmacologic interventions can significantly improve quality of life. Patient-centered case-based decision-making is crucial, particularly in the setting of malignancy and high opioid use.
Resources
2009 – Muehlbauer – chemo_XRT induced diarrhea
2019 – Crockett – OIC guideline