What are the recommendations for managing constipation in inpatients?

Inpatient Constipation Management

Start with polyethylene glycol (PEG) 17g dissolved in 8 ounces of liquid twice daily as first-line pharmacological therapy for hospitalized patients with constipation, as this has the strongest evidence for efficacy and safety. 1, 2

Initial Assessment

Obtain a focused history targeting:

• Current bowel movement frequency, stool consistency (Bristol scale), straining severity, and sensation of incomplete evacuation 2
• Complete medication list identifying constipating agents: opioids, anticholinergics, calcium channel blockers, and iron supplements 2
• Baseline fluid intake, dietary fiber consumption, and current activity level 2
• Privacy concerns, toilet access limitations, and mobility restrictions 2

Perform physical examination:

• Abdominal exam assessing for distension, tenderness, and palpable stool 2
• Digital rectal examination to identify fecal impaction or rectal masses 2
• Rule out bowel obstruction if severe symptoms present, considering abdominal X-ray if clinically indicated 3

Non-Pharmacological Interventions (Implement Concurrently)

Environmental modifications:

• Ensure privacy and comfort during toileting, as environmental factors significantly impact bowel function 2, 3
• Position patient with small footstool to assist gravity and facilitate easier defecation 2, 3
• Maintain regular toileting schedule, particularly after meals to leverage gastrocolonic response 2, 3

Lifestyle measures:

• Increase fluid intake to at least 2 liters daily, especially for patients with low baseline consumption 2, 3
• Encourage mobility within patient limits—even simple bed-to-chair transfers improve bowel function 2, 3
• Do NOT increase dietary fiber without adequate fluid intake and physical activity, as fiber without sufficient hydration worsens constipation 3

Pharmacological Management Algorithm

First-Line: Osmotic Laxatives

Polyethylene glycol (PEG) is the strongly recommended first-line agent:

• Dosing: 17g (one heaping tablespoon) dissolved in 8 oz water twice daily 2
• Increases complete spontaneous bowel movements by 2.9 per week compared to placebo 1, 2
• Moderate certainty of evidence with durable response over 6 months 1
• Common side effects: abdominal distension, loose stool, flatulence, nausea 1

Alternative First-Line: Stimulant Laxatives

Stimulant laxatives are equally appropriate first-line options, particularly for opioid-induced or medication-related constipation:

• Senna: 2-3 tablets (8.6mg each) two to three times daily, titrated to effect (maximum 8-12 tablets daily) 2
• Bisacodyl: 10-15mg orally 2-3 times daily 2

Second-Line Options

If PEG or stimulant laxatives fail:

• Lactulose: 30-45mL (20-30g) three or four times daily, adjusted to produce 2-3 soft stools daily 1, 4
• Improvement may occur within 24 hours but may take 48 hours or longer 4

Management of Fecal Impaction

When digital rectal exam identifies full rectum or fecal impaction, suppositories and enemas are preferred first-line therapy:

• Bisacodyl suppository: 10mg once or twice daily 2
• Glycerin suppositories for mild cases 2
• Lactulose retention enema: 300mL lactulose mixed with 700mL water or saline, retained 30-60 minutes, repeated every 4-6 hours if needed 4
• Contraindication: Enemas are contraindicated in neutropenic or thrombocytopenic patients 2

Prophylactic Management

For patients receiving opioids:

• Initiate prophylactic laxatives (senna or PEG) concurrently with opioid initiation, rather than waiting for constipation to develop 2, 3
• Patients do not develop tolerance to opioid-induced constipation, requiring ongoing prophylactic treatment 2
• Methylnaltrexone (peripherally acting μ-opioid antagonist) can be considered for opioid-induced constipation persisting despite laxative therapy 1

Advanced Therapies (Outpatient Transition)

For patients not responding to over-the-counter options before discharge:

• Strongly recommended: Linaclotide, plecanatide, prucalopride 1
• Conditionally recommended: Lubiprostone 1

Critical Pitfalls to Avoid

• Do not discontinue laxatives prematurely—ensure adequate trial periods before escalating therapy 1
• Do not rely solely on lifestyle modifications for symptom control, as evidence shows limited influence when used alone 3
• Discontinue non-essential constipating medications after medication review 3
• Advise against home remedies or over-the-counter products purchased online, as these may interfere with prescribed treatments 3
• If diarrhea accompanies constipation, rule out fecal impaction with overflow 3

Special Populations

Elderly inpatients (24-50% prevalence):

• Enhanced risk of complications requiring particular attention 2
• Avoid long-term magnesium-based laxatives due to potential toxicity 5
• PEG is particularly attractive in frail elderly patients who cannot maintain adequate hydration for bulk-forming laxatives 2