What is the Malone procedure (Antegrade Continence Enema, ACE)?

Malone Procedure (Antegrade Continence Enema, ACE)

The Malone procedure is a surgically-created appendicostomy that provides a catheterizable channel to the cecum for delivering antegrade colonic enemas, primarily used to manage fecal incontinence and constipation in patients who do not respond to medical therapy. 1

Definition and Purpose

• The Malone Antegrade Continence Enema (MACE or ACE) procedure creates a small stoma through which antegrade enemas can be administered to empty the colorectum 1
• It was originally described by Malone for treating intractable fecal incontinence in children but has since been adapted for use in adults 1, 2
• The procedure allows for improved bowel management when retrograde enemas or other conservative measures have failed 1

Surgical Technique

• The traditional approach uses the appendix, which is brought to the abdominal wall to create a small catheterizable stoma 2
• When the appendix is unavailable or stenosed, surgical alternatives include:
  • Creation of a "neoappendix" from the cecum 2
  • In situ technique using windows developed in the appendiceal mesentery for imbrication 3
  • Lateral or medial-based colonic tubes (with lateral tubes having higher rates of stenosis) 4
• The stoma can be placed at different sites:
  • Umbilical (more cosmetically appealing but potentially higher risk of leakage) 5
  • Right lower quadrant (potentially lower complication rates) 5
• If a patient requires both urinary and fecal continence procedures, the appendix can be split into two segments to create both a MACE and a Mitrofanoff channel 1

Clinical Applications

• Primary indications include:
  • Fecal incontinence unresponsive to medical management 1
  • Intractable constipation 1, 2
• Particularly beneficial in patients with:
  • Neurogenic bowel dysfunction (e.g., spina bifida, myelomeningocele) 1, 3
  • Functional constipation resistant to conventional therapies 3
• The procedure is more commonly performed in children but can be effective in selected adult patients 2

Efficacy

• Success rates vary by population:
  • Children: approximately 80% achieve complete or near-complete fecal continence 1
  • Adults: approximately 50% show significant improvement 1
• In one study of 16 adult patients, those who continued using the stoma reported high satisfaction, with reduced defecation time (from 170 to 45 minutes in constipated patients) and significant improvement in fecal incontinence 2
• A larger study of 127 patients (mostly children) reported 91% achieving fecal continence with a mean follow-up of 26.9 months 3

Complications and Limitations

• Overall complication rates are high, with up to 68% of patients experiencing at least one complication 5
• Common complications include:
  • Stomal stenosis (23.7% of patients) 5
  • Stomal leakage (27.8% of patients) 5
  • Stomal site infection 5
  • Rare but serious complications include cecal volvulus and small bowel obstruction 3
• Long-term issues often require surgical revision:

  • 50% of patients require revision, reversal, or conversion to a formal stoma within 3 years 1

• The use of permanent stomal buttons/catheters affects complication rates:
  • Increased risk of stomal leakage and infection 5
  • Decreased risk of stomal stenosis 5

Practical Considerations

• Administration of antegrade enemas is time-intensive:
  • Instillation and washout typically takes 20-60 minutes 1
  • Requires patient or caregiver commitment to regular use 1
• The procedure does not address underlying pelvic floor dysfunction, which is often the primary issue in defecatory disorders 1
• Clinical guidelines suggest that anterograde colonic enema procedures are not effective long-term solutions for adults with defecatory disorders 1

Patient Selection

• Best candidates include:
  • Patients with fecal incontinence that significantly impacts quality of life 1
  • Those who have failed conservative management including dietary modifications, fiber supplements, medications, and retrograde enemas 1
  • Patients with neurogenic bowel dysfunction 3
• The procedure may be considered during planned lower urinary tract reconstruction in patients with concurrent fecal continence issues 1

While the Malone procedure can provide significant improvement in quality of life for selected patients, particularly children with neurogenic bowel, its high complication rate and limited long-term efficacy in adults must be carefully considered when recommending this intervention 1.