What is the MACE (Malone Antegrade Continence Enema) procedure for patients with severe fecal incontinence or constipation due to underlying neurological conditions?

What is the MACE Procedure?

The Malone Antegrade Continence Enema (MACE) procedure is a surgical technique that creates a catheterizable channel (typically using the appendix) from the abdominal wall to the cecum, allowing patients to administer antegrade enemas to empty the colon and achieve fecal continence. 1

Surgical Technique and Anatomical Approach

The MACE procedure involves creating a continent catheterizable channel to the right colon, most commonly using the appendix as the conduit. 1 The appendix is brought to the abdominal skin surface, creating a small stoma through which a catheter can be inserted to deliver irrigation fluid directly into the cecum. 1

Key technical variations include:

• Imbricated vs. non-imbricated channels: The cecum can be imbricated (folded) around the appendiceal channel to improve continence and reduce perforation risk 2
• Stomal location: The stoma can be placed in the right lower quadrant or at the umbilicus, though umbilical placement in younger patients (<12 years) with imbricated, non-intubated stomas carries higher leakage rates 3
• Surgical approach: Can be performed open, laparoscopically, or robotically, with robotic techniques allowing for imbrication without requiring a large incision 2

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

Primary Indications

The MACE procedure is indicated for patients with fecal incontinence or intractable constipation who have failed conservative medical management. 1

The procedure is particularly beneficial in patients with neurogenic bowel dysfunction, including:

• Spina bifida or myelomeningocele 1
• Spinal cord injury 4, 5
• Cerebral palsy 4
• Other neurologic diseases causing fecal incontinence 4

How the Procedure Works

Patients or caregivers insert a catheter through the MACE stoma and instill 500-1000 mL of irrigation fluid (typically tap water, saline, or solutions containing stimulant laxatives) into the cecum. 1 The fluid travels antegradely (in the normal direction of colonic flow) through the colon, promoting complete evacuation of stool. 1 This process typically takes 20-60 minutes and requires patient or caregiver commitment to regular use. 1

Efficacy and Success Rates

Success rates differ substantially between pediatric and adult populations:

• Children: Approximately 80% achieve complete or near-complete fecal continence 1
• Adults: Only approximately 50% show significant improvement 1, 6

In one adult series, only 50% of patients were still successfully using the MACE after an average follow-up of 41.7 months, with higher failure rates in chronically constipated patients without fecal soiling. 6 Successful treatment is associated with significant improvement in quality of life. 5

Complications and Long-Term Outcomes

Over 50% of patients require revision, reversal, or conversion to a formal stoma within 3 years, making this a procedure with substantial long-term failure rates. 1

Common complications include:

• Stomal stenosis: Occurs in approximately 24% of patients 3
• Stomal leakage: Occurs in approximately 28% of patients 3
• Stomal site infection: More common with permanent button/catheter devices 3
• Catheter false passage with perforation: Occurs in approximately 3.7% of patients and can lead to peritonitis requiring immediate laparotomy 7

Critical technical factors affecting complications:

• Permanent stomal buttons/catheters increase risk of leakage and infection but decrease risk of stenosis 3
• Umbilical stomas in preteen patients with imbricated, non-intubated channels have higher leakage rates compared to right lower quadrant placement 3

Patient Selection and Positioning in Treatment Algorithm

The MACE procedure should be reserved for patients who have failed a rigorous trial of conservative therapy, including optimized bowel routines, dietary modifications, laxatives, and transanal irrigation. 8

According to the American Gastroenterological Association, anterograde colonic enema procedures such as MACE are not effective long-term solutions for adults with defecatory disorders. 1 Best candidates include patients with fecal incontinence that significantly impacts quality of life and those who have failed conservative management. 1

The procedure is positioned after:

• Conservative management (fiber, fluids, scheduled toileting) 8
• Pharmacological management (osmotic and stimulant laxatives) 8
• Transanal irrigation systems 8
• Sacral nerve stimulation (which has higher success rates for fecal incontinence) 4, 9

Critical Pitfalls to Avoid

Do not proceed with MACE without ensuring patients have undergone an adequate trial of less invasive options, including transanal irrigation and sacral nerve stimulation, which have better evidence for efficacy in adults. 4, 8 Many patients undergo surgical therapy without rigorous trials of conservative therapy. 4

Prompt diagnosis of catheter false passage is crucial: Patients presenting with abdominal pain after irrigation or reporting traumatic catheterization should undergo immediate imaging with contrast studies to identify extravasation. 7 Early endoscopic evaluation with catheter placement can preserve continence and decrease morbidity. 7

Set realistic expectations: The high revision rate (>50% within 3 years) and time-intensive nature of daily irrigations (20-60 minutes) must be discussed thoroughly with patients and caregivers before proceeding. 1