What are the different types of enemas used to treat severe constipation?

Types of Enemas for Severe Constipation

For severe constipation, suppositories and enemas are the preferred first-line therapy when digital rectal examination identifies a full rectum or fecal impaction. 1

Common Types of Enemas

Saline-Based Enemas

• Normal saline enemas distend the rectum and moisten stools with less irritating effects on rectal mucosa compared to other types, though large volume watery enemas risk water intoxication if retained 1
• Hypertonic sodium phosphate enemas both distend and stimulate rectal motility with uncommon adverse effects 1, 2
  • Contraindicated in patients with renal insufficiency, pre-existing electrolyte disturbances, congestive heart failure, and cirrhosis or ascites 2
  • Should be used with caution in elderly patients, hypertensive patients, and those taking ACE inhibitors, NSAIDs, or diuretics 2
  • Associated with water and electrolyte disturbances, particularly in patients under 18 or over 65 years of age 3

Soap-Based Enemas

• Soap solution enemas (1 mL of mild liquid soap per 200 mL of solution, total volume 1000 mL) may cause chemical irritation of the mucous membranes 1

Osmotic Enemas

• Osmotic micro-enemas contain sodium lauryl sulfoacetate (wetting agent) and osmotic agents (sodium citrate and glycerol) that create an osmotic imbalance bringing water into the bowel to soften stool and stimulate contractions 1
  • Work best if rectum is full on digital rectal examination 1

Stimulant Enemas

• Bisacodyl enemas promote intestinal motility by causing water passage into the intestinal lumen from vessels 1
  • Can cause abdominal discomfort including cramps, pain, and diarrhea 1, 2
  • Preferred over sodium phosphate in patients with renal impairment 2

Oil-Based Enemas

• Retention enemas are held within the large intestine for at least 30 minutes 1
  • Warm oil retention enemas (cottonseed, arachis or olive oil) lubricate and soften stool for easier expulsion 1
  • Arachis oil (peanut oil) is contraindicated in patients with peanut allergies 1
  • Olive oil enemas have shown effectiveness in treating fecal impaction in 77.6% of children with severe chronic constipation 4

Other Types

• Docusate sodium enemas soften stool by aiding water penetration of the fecal mass, taking 5-20 minutes to work 1
  • Common adverse effects include anal or rectal burning and pain, and short-lasting diarrhea 1
• Milk and molasses enemas have been used as a treatment of last resort for unresolved constipation, with retrospective studies showing no significant safety concerns in hospitalized adults 5
• Colonic washout enemas using water (20 mL/kg) have shown effectiveness in children with persistent constipation 6
• PeristeenⓇ anal irrigation system introduces water (500-700 mL) into the bowel using a rectal catheter while sitting on the toilet, stimulating peristalsis and bowel emptying 1
  • Evidence primarily from studies on neurogenic bowel dysfunction in patients with spinal cord injury 1
  • Requires close supervision to ensure safe administration 1

Contraindications for Enema Use

Enemas are contraindicated in patients with:

• Neutropenia or thrombocytopenia
• Paralytic ileus or intestinal obstruction
• Recent colorectal or gynecological surgery
• Recent anal or rectal trauma
• Severe colitis, inflammation or infection of the abdomen
• Toxic megacolon
• Undiagnosed abdominal pain
• Recent radiotherapy to the pelvic area 1, 2

Selection Algorithm

1. For patients with a full rectum identified on digital rectal exam:

   • First-line: Suppositories and enemas 1

2. For patients with normal renal function:

   • Consider sodium phosphate enemas 2

3. For patients with renal impairment:

   • Choose bisacodyl over sodium phosphate 2

4. For patients with fecal impaction:

   • Consider oil retention enemas (olive oil or arachis oil if no peanut allergy) 1, 4

5. For patients requiring frequent bowel preparation:

   • Sodium phosphate is better tolerated if renal function is normal 2

Common Pitfalls to Avoid

• Using sodium phosphate in patients with renal dysfunction can lead to serious electrolyte disturbances 2, 3
• Using any enema in patients with neutropenia or thrombocytopenia increases risk of complications 1, 2
• Failing to consider patient-specific factors like age, comorbidities, and medication use when selecting enemas 2
• Large volume watery enemas risk water intoxication if retained 1
• Overuse of sodium phosphate enemas in patients at risk for electrolyte abnormalities 2
• Using both sodium phosphate and bisacodyl simultaneously could potentially cause excessive bowel stimulation, leading to severe cramping and electrolyte disturbances 2