The Malone Antegrade Continence Enema (MACE) procedure is a specialized surgical intervention designed to provide a long-term solution for individuals suffering from severe bowel dysfunction. The procedure involves creating a channel, or stoma, on the abdominal wall that connects directly to the beginning of the large intestine, or colon. This channel allows for the “antegrade,” or forward-moving, administration of enema fluid, which effectively flushes the colon from top to bottom. By enabling regular, predictable, and complete bowel emptying, the MACE procedure aims to establish continence and resolve chronic constipation.
Understanding the Need for the Procedure
The MACE procedure is typically considered a treatment of last resort, reserved for patients whose severe bowel issues have not responded to less invasive medical management, such as diet changes, laxatives, or traditional rectal enemas. It is a surgical option for both adults and children who experience intractable fecal incontinence or refractory chronic constipation. The goal is to provide a reliable method for complete colonic cleanout, which prevents accidental stool leakage and relieves the discomfort of impaction.
A significant portion of patients requiring MACE have underlying neurological conditions that affect bowel function, such as Spina Bifida or sacral agenesis, which impair the nerves controlling the colon and anal sphincter. Other indications include congenital issues like anorectal malformations and Hirschsprung disease, which structurally compromise the digestive tract.
The underlying problem in many of these conditions is that the colon does not propel stool effectively, or the rectum is unable to completely empty. Traditional enemas administered through the rectum only clean the lower part of the colon, which is often insufficient for full evacuation. Prior to the surgery, a full medical workup, including motility tests and imaging, is often performed to confirm the medical necessity of the intervention.
How the Surgery is Performed
The MACE procedure, also known as a Malone appendicostomy, most commonly utilizes the patient’s own appendix to create the functional channel. The appendix is gently separated from surrounding tissues while preserving its blood supply, and its tip is brought out to the skin of the abdomen. This opening on the abdominal wall is called a stoma, and it is usually placed in a discreet location, often at or near the belly button (umbilicus) or in the right lower quadrant.
A specialized technique is used to create a one-way valve mechanism at the connection point between the appendix and the colon. This internal valve, constructed from the patient’s natural tissues, is designed to be “continent,” meaning it prevents the leakage of stool or fluid from the stoma when a catheter is not inserted. If the appendix has been previously removed or is unsuitable, surgeons can create a neo-appendicostomy using a small segment of the small intestine, typically the ileum, to form the channel.
The procedure is often performed using minimally invasive laparoscopic techniques, which involve small incisions and a camera. Following the operation, a temporary tube, such as a Foley catheter, is placed in the new channel and secured to the skin to keep the pathway open while it heals. This tube typically remains in place for a period of two to six weeks, after which the daily bowel routine can begin.
Establishing the Daily Bowel Routine
The success of the MACE procedure relies entirely on establishing a consistent and effective daily bowel management routine. This routine involves the patient or caregiver inserting a lubricated, thin plastic tube, or catheter, through the stoma and into the colon. Once the catheter is in place, it is connected to an enema administration set, often a gravity-flow bag filled with the flushing solution.
The enema solution is typically a mixture of water and salt (saline), although plain tap water is also commonly used. The solution may also be customized with additives like polyethylene glycol (PEG), glycerin, or mineral oil to enhance the flushing effect, especially in cases of hard stool.
The patient is seated on the toilet during the administration, which usually takes about 5 to 10 minutes for the fluid to infuse. After the infusion is complete and the catheter is removed, the patient waits for the solution to work and for the bowel to evacuate, a process that can take between 30 and 60 minutes. The timing and volume of the flush are highly individualized and adjusted until the patient achieves a predictable, clean evacuation, often performed daily or every other day.
Long-Term Outcomes and Quality of Life
The MACE procedure offers a significant long-term benefit by providing patients with independence and control over their bowel function. For many, the ability to predictably empty the bowel eliminates fecal incontinence and chronic constipation, leading to substantial improvement in social participation, school attendance, and overall psychological well-being. Studies have reported high rates of continued MACE use, with many patients successfully managing their symptoms years after the operation.
Despite the functional success, long-term management can present challenges, which often require further intervention. The most common issue is stoma stenosis, which is a narrowing of the opening, necessitating a minor revision surgery to keep the channel wide enough for catheter insertion. Stomal leakage, where mucus or small amounts of stool seep from the opening, is another frequent complication, though it is usually manageable with dressings.
While the success rate, defined as the continued use of the MACE, can be around 70% to 75%, a smaller percentage of patients achieve complete continence without any further issues. Some patients may eventually require more complex surgical procedures if the MACE fails to provide adequate relief over time.