Enema

1. Classification by Purpose

A. Evacuant / Cleansing Enemas

• Normal saline - safest, most widely used base solution; isotonic so minimal electrolyte disturbance
• Phosphate enema (Fleet Enema) - sodium phosphate solution; acts as an osmotic agent drawing water into the bowel. Dosing:
  • 2-4 yr: 33 mL (half of Fleet Pedia-Lax)
  • 5-11 yr: 66 mL (Fleet Pedia-Lax)
  • ≥12 yr and adults: 133 mL or 230 mL (Fleet Enema Extra)
  • Caution: Repeated sodium phosphate enemas can cause hypocalcemia. Use cautiously in children with renal impairment.
• Glycerin enema - hygroscopic agent and lubricant. Retains water intraluminally, stimulates peristalsis; produces evacuation in under 1 hour. Given as 5-15 mL of an 80% solution rectally. May cause local burning or hyperemia.
• Soap suds enema - irritant effect; less commonly used today
• Olive oil retention enema - used to soften hard, impacted stool before evacuation; especially useful to prevent massive fecal impaction (Pye's Surgical Handicraft)
• Mineral oil enema - lubricant; part of disimpaction protocols
• Hypotonic enemas - repeated use can cause hyponatremia; avoided

B. Contrast / Diagnostic Enemas

• Barium enema - historically used for imaging the colon (polyps, carcinoma, diverticulae). Largely replaced by colonoscopy and CT colonography in most centers.
• Water-soluble contrast enema - safer alternative when perforation is a risk (e.g., suspected Hirschsprung disease in neonates). A transition zone on contrast enema (indicating the aganglionotic segment) is the classic radiological sign of Hirschsprung disease. Contrast remaining in the rectum >24 hours post-study is also suggestive. In neonates, a lateral rectal view may reveal abnormal spasm of the distal segment even when a transition zone is not obvious.

C. Therapeutic / Medicated Enemas

• Corticosteroid enemas / foam - used in distal ulcerative colitis and proctitis
• Mesalazine (5-ASA) enemas - first-line for distal UC
• Lactulose enemas - used in hepatic encephalopathy to reduce ammonia absorption
• Sucralfate enemas - radiation proctitis

D. Antegrade Continence Enema (ACE / Malone Procedure)

• Initial enema volume: 20 mL/kg of solution (normal saline, glycerin, bisacodyl, polyethylene glycol, or phosphate as additive)
• Washout time: 30-60 minutes; usually administered in the early evening
• Frequency: typically daily initially, decreasing to alternate days once established
• Steady state may not be achieved for up to 6 months
• Complications include pain/discomfort during instillation (usually resolves within 3 months), buttock pressure sores (use padded toilet seats), and fecal impaction from infrequent washouts
• Water intoxication and electrolyte abnormalities are possible, particularly with large volumes or inappropriate solutions (Campbell-Walsh Urology)

2. Indications

3. Disimpaction Protocol (Pediatric)

• High-dose PEG (1-1.5 g/kg/day for 3-6 days) with or without saline, sodium phosphate, or mineral oil enemas daily for 3-6 days
• Enema volumes: 30 mL (<4 yr), 60 mL (4-10 yr), 120 mL (>10 yr); total volume may be up to 500-1000 mL for heavy fecal loads
• Failure or intolerance may necessitate hospitalization with NGT delivery and IV fluids, or digital disimpaction under anesthesia

4. Complications

5. Administration Technique (General)

1. Position patient in left lateral decubitus (Sim's position)
2. Lubricate nozzle; insert 7-10 cm into rectum
3. Instill fluid slowly; encourage retention for prescribed time
4. Patient should retain fluid for at least 5-15 minutes before defecating (retention enemas: 30-60 minutes)
5. Warm the solution to body temperature to reduce cramping