 be able to find the rectum and may find and damage other, unexpected, structures, such as the posterior urethra, seminal vesicles, vas deferens, and ectopic ureters during the search for the rectum. Finally, without fecal diversion, there is the risk of dehiscence and infection. These complications may compromise the ultimate functional prognosis.
Decision-making for female newborns
The decisions involved in managing the female newborn are less complicated. In 90% of patients, a meticulous perineal inspection will demonstrate the anorectal defect. Waiting 16–24 hours for enough abdominal distension to demonstrate the presence of a rectoperineal fistula or rectovestibular fistula applies to females as well.
The most common anomaly in females is a rectovestibular fistula (Figure 5). Perineal inspection shows a normal urethra, normal vagina, and another orifice, which is the rectal fistula in the vestibule. The safest option for a surgeon without extensive experience in anorectal anomalies when faced with a baby with clinical evidence of a rectovestibular fistula is to perform a diverting colostomy. Colostomy prior to the main repair avoids the complications of infection and dehiscence. Definitive repair of this anomaly in the newborn period should be reserved for surgeons with significant experience repairing these defects. This anomaly has an excellent prognosis and therefore complications that could affect future continence must be avoided.
Unfortunately, the most common referral for redo operations to tertiary centers that care for anorectal anomalies are for patients with rectovestibular fistulas who underwent a failed primary repair in the newborn period.
Occasionally, the fistulas are big enough to decompress the gastrointestinal tract, and may be dilated to facilitate fecal drainage until the baby is older and a definitive repair is performed. Definitive repair involves a posterior sagittal approach. The most delicate part of this operation is the separation of the rectum and vagina, which share a common wall. Females like males can have a rectoperineal fistula and for them an anoplasty in the newborn period should be performed. Like in males, less than 5% of female babies have no clinical evidence of the location of the rectum after 24 hours. They may have imperforate anus with no fistula. A cross-table lateral x-ray should be performed, and will help determine the need for a colostomy.
As discussed previously, the surgeon must decide in the newborn period whether the child requires fecal diversion with a colostomy, or can undergo a primary repair procedure.
The preferred colostomy is a descending colostomy, i.e. made from the descending portion of the colon located in the lower-left quadrant of the abdomen, with separated stomas . The proximal stoma is connected to the upper gastrointestinal tract and drains stool. The distal stoma, also called a mucous fistula, is connected to the rectum and will drain small amounts of mucus material. The advantages of this type of colostomy are many: 1) it defunctionalizes only a small portion of distal colon, 2) in cases of large rectourinary fistulae in which the patient passes urine into the bowel, the urine comes out easily through the mucous fistula, avoiding problems of hyperchloremic acidosis due to urine absorption. Urinary tract infections are also avoided, 3) it is relatively easy to wash and clean the part of the colon distal to the colostomy, 4) distal colostograms are easy to perform, 5) the sigmoid loop is kept distal to the colostomy which provides enough length to reach the perineum during the definitive pull-through procedure, 6) the separated stomas prevent spillage of stool from proximal to distal bowel, which avoids impacted distal stool and urinary tract infections, 7) there is a low incidence of prolapse with this technique. Proximal stoma prolapse in a normally rotated colon should not happen with this technique because the colon is well fixed to the retroperitoneum just before the colostomy rises to the skin level. The distal stoma may prolapse because i