Pediatric Imperforate Anus (Anorectal Malformation) Treatment & Management

Updated: Aug 08, 2016
  • Author: Nelson G Rosen, MD, FACS, FAAP; Chief Editor: Carmen Cuffari, MD  more...
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Treatment

Medical Care

Newborns with imperforate anus should not be fed and should receive intravenous hydration. Life-threatening comorbidities take precedence and must be treated first.

If a urinary fistula is suspected, broad-spectrum antibiotics can be administered, although anaerobic coverage is unnecessary within the first 48 hours of life. Any cardiac murmurs identified upon physical examination should be evaluated using echocardiography prior to surgical intervention. The remainder of treatment includes diagnostics and surgical evaluation and management.

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Surgical Care

The decision-making process aims to determine which children should undergo primary repair in the neonatal period and which children require colostomy and definitive repair in a staged fashion. Children with anorectal malformations may undergo one or several of the following surgical procedures based on the child's presentation, physical examination findings, and imaging study findings.

  • Neonatal colostomy

    • A colostomy is performed in children who are not amenable to primary pull-through either because of malformation complexity (any urinary fistula in boys, vestibular fistula and cloaca in girls, no fistula in either sex >1 cm from perineal skin) or associated comorbidity.

    • The colostomy is usually fashioned through a left lower quadrant incision. The colon is divided at the point where the descending colon meets the sigmoid colon, and both ends are brought to the abdominal wall. By fashioning the colostomy at this location, the entire sigmoid colon is kept in place; thus, when the pull-through is eventually performed, a large portion of the colon is available for the surgeon to bring down to the perineal skin.

    • The mucous fistula (the downstream segment) should be very small, flush with the skin, and far enough from the proximal end to be outside the colostomy appliance (or under the flange) to avoid continued urinary soiling with feces.

    • During this operation, the distal segment of the colon must be exhaustively irrigated to clean out the impacted meconium, which is always significant. This prevents postdiversion urinary sepsis and allows for effective distal colostography.

  • Primary neonatal pull-through without colostomy

    • Many pediatric surgeons opt for primary pull-through in children with perineal fistulas (or no fistulas) and close (< 1 cm) rectal pouches on 24-hour lateral pelvic radiography. Some pediatric surgeons who specialize in colorectal problems often offer the same procedure for girls with vestibular fistulas.

    • Cystoscopy is usually performed to rule out associated malformation. This is performed immediately prior to the pull-through operation. A Foley catheter is inserted following the cystoscopy.

    • The preferred surgical approach is the posterior sagittal approach developed by Peña et al.

      • The child is placed in the prone position with generous padding under the face and chest and a large bolster under the hips to elevate the area of interest.

      • A muscle stimulator is used to show the precise position of the rectal muscle complex to enable exact division at the midline. The midline for this operation is defined by the line that precisely divides the muscle complex in half.

      • Dissection proceeds until the rectal pouch is identified. The pouch is then mobilized until adequate length is obtained and the rectum is fully separated from its attachment to the genitourinary tract. Even if the structures do not communicate, they remain intimately associated until fully mobilized. This step ensures that the surgeon does not miss a fistula that was missed on urinalysis findings.

      • Once the rectum has been mobilized, the muscle stimulator is used to mark the anterior and posterior limits of the muscle complex. The perineal body is then reconstructed, and the rectum is tacked down in the middle of the muscle complex. The posterior wound is closed and anoplasty is performed.

  • Posterior sagittal pull-through with colostomy

    • This approach is used in boys with rectourinary fistula (bulbar, prostatic, or bladder-neck fistula), in girls with cloaca or vestibular fistula, and in patients of either sex who do not have a fistula when the rectal pouch is further than 1 cm on 24-hour lateral prone abdominal radiography.

    • The approach is also used in children who may have malformations that were amenable to primary neonatal pull-through but were unable to undergo such a procedure because of extreme prematurity or other comorbidity.

    • Colostomy is performed after 24 hours (or immediately if one of the above diagnoses is made based on either physical examination findings or meconium in the urine).

    • Several weeks following colostomy, distal colostography is performed, and the specifics of the malformation are clarified.

    • Cystoscopy is usually performed to clarify anatomy and to rule out associated malformation. This is performed immediately prior to the pull-through operation. A Foley catheter is inserted following the cystoscopy, except in girls with cloaca.

    • The reconstructive procedure varies based on the malformation, but the essential concepts include identifying and separating the rectum from other structures, dividing and ligating any fistulas, and fully reconstructing the pelvic anatomy with placement of the rectum within the confines of the muscle complex. Procedures for specific malformations are as follows:

      • Vestibular fistulas are directly visible but have the longest common wall between the rectum and vagina and require significant delicate mobilization to avoid holes in either structure.

      • The posterior sagittal approach is used in boys with bulbar or prostatic urethral fistulas. The rectum is isolated and opened, and the fistula is identified through progressive distal opening. Once the fistula is identified, the rectum proximal to it may be mobilized, and the fistula is then ligated. Reconstruction then proceeds with primary pull-through, as described above.

      • Abdominal (open or laparoscopic) and posterior sagittal approaches are best in boys with bladder-neck fistulas because the fistula is best identified in the abdomen.

      • Cloaca procedures are complex. A short – common-channel cloaca can be repaired using total urogenital mobilization. The posterior sagittal wound is opened into the cloaca, which is then further proximally opened until the urethral orifice is identified and catheterized. The rectum is then sought. In girls with 2 hemivaginas (50%), the rectum opens in the vaginal septum, although significant asymmetry may be present. After identification, the rectum is separated from the urogenital tract and completely mobilized. The urogenital tract is then mobilized as a solitary structure until the urethral orifice reaches the perineum. This is then reconstructed, and the muscle is marked to enable creation of an adequate vaginal opening and perineal body without impinging on rectal space.

      • A long – common-channel cloaca repair often necessitates formal separation of the bladder and vagina, which requires laparotomy and ureteral catheterization. Vaginal replacement is sometimes necessary if the vaginal length is insufficient for reconstruction.

  • Colostomy closure: Once the wound has completely healed and postoperative dilations have achieved their goal (ie, the neoanus is at the desired size), the colostomy may be closed in traditional surgical fashion.

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Consultations

The following consultations may be indicated:

  • Pediatric surgeon: Early consultation with a pediatric surgeon experienced with these anomalies is essential. Ill-conceived procedures during the newborn period may have lifelong consequences for the patient.

  • Neurosurgeon: Consultation with a neurosurgeon is warranted if a tethered spinal cord is present (25% of all cases).

  • Urologist: The need for consultation with a urologist depends on the malformation and the individual pediatric surgeon.

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Diet

After the obstruction is relieved using colostomy, primary pull-through, or dilation, children do not require special diet. The most common complication of imperforate anus repair is constipation or anal incontinence; therefore, diet can be a crucial part of management. Many patients may require laxatives, enemas, or other medications or irrigations in addition to dietary manipulations. [7] Children should avoid constipating foods, such as those included in the bananas, rice, applesauce, and toast (BRAT) diet. High-fiber and laxative foods (whole-grain foods and breads, dairy, fruits, vegetables, greasy foods, spicy foods) should be encouraged. Unfortunately, dietary manipulation is often of limited effectiveness because of the fussy nature of most children regarding diets. Fiber supplements and laxatives can be critically important in avoiding constipation, which can significantly affect prognosis.

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Activity

Children with anorectal malformations are often otherwise healthy. Activity limitations are usually related only to the period around their surgical procedures.

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