noplasty. After colostomy closure, severe diaper rash is common because the perineal skin has never before been exposed to stool.
• Functional Disorders
It is also the most important problem to avoid after definitive repair for female patients with rectovestibular or rectoperineal fistula and for male patients with rectobulbarurethral fistula, imperforate anus without fistula, and rectoperineal fistula. Failure to avoid constipation can result in megarectum and megasigmoid, and can lead to fecal impaction and overflow incontinence. The origin of the problem of constipation is unknown. It was originally thought that the perirectal dissection caused a degree of denervation that resulted in constipation. However, on careful review of the largest series of these patients, it became clear that those with the most benign defects and thus the least amount of perirectal dissection had the worst constipation.
The presence of a megarectum prior to the pull-through does correlate with postoperative constipation. Megarectum is more common in patients for whom a transverse or loop colostomy was performed in the newborn period. Constipation appears to be a hypomotility disorder secondary to chronic bowel dilatation. Or, perhaps it is the hypomotility that causes dilatation, which in turn results in constipation, creating a vicious cycle.
When a patient with a megasigmoid has been shown to be fecally continent, resection of the sigmoid has been found to dramatically reduce the patient's laxative requirements. The descending colon with normal caliber and normal motility is anastomosed to the rectum at the peritoneal reflection. This applies for a select group of patients with enormous daily laxative requirements to keep their colons clean. Performance of a new pull-through operation should be avoided so that the patient's rectal reservoir is preserved. Loss of the rectal reservoir could lead to a worse problem of incontinence with a patient who now has diarrhea.
The key in these patients is to manage constipation proactively and avoid it after the pull-through procedure. The patients must be followed regularly, and laxatives and dietary manipulations are begun at the first sign of constipation.
Occasionally constipation becomes so severe that patients develop chronic fecal impaction and constant soiling. Patients like this are often referred with "fecal incontinence." However, if the patient has a good prognosis type of anorectal anomaly, often this incontinence is actually overflow pseudoincontinence. Once the constipation is managed, they become continent.
Less frequently than constipation, some patients may experience soiling. While in a patient with a good prognosis, this may be overflow incontinence, it may also represent true fecal incontinence in cases of very high imperforate anus or poor muscles and an abnormal sacrum. A contrast enema is helpful in differentiating these two groups of patients. Patients with real incontinence require a bowel management program, which involves cleaning of the child's colon once a day by the use of a suppository, an enema or a colonic irrigation .
Giving the enema after the main meal of the day allows a more efficient cleansing of the bowel by taking advantage of the gastrocolic reflex. Antegrade enema procedures, whereby enema is introduced in a conduit via appendicocecostomy, has been devised to help the patient clean its bowel [30, 31]. The artificial bowel sphincter and electrically stimulated gracilis neosphincter are two relatively new techniques that have been used for the treatment of patients with severe refractory fecal incontinence.
Patients who have undergone abdominoperineal operations for imperforate anus that included resection of the rectum suffer from a tendency to have diarrhea due to a lack of a rectal reservoir. These patients' incontinence is much harder to manage because they pass stool constantly.
Bowel movement pattern prior to potty-training may give an important clue as to the child's potential for continence. For example, a one-year-old child who has undergone a pull-th