Anal atresia is one such defect (abnormality) that occurs while the baby is still growing in the mother’s body before it is born. This defect or malformation occurs in the baby during the fifth to seventh week of the mother’s pregnancy.
With these defects, the anus (the end of the large intestine, the opening through which feces pass) and the rectum (the large intestine just above the anus) do not develop normally.
Prevalence of anal atresia.
Anal atresia affects up to 1 in 5,000 babies and is slightly more common in males.
No one knows the exact reason why some babies will have anal atresia. The exact cause of anal atresia is not known. In some cases, environmental factors or the use of medications during pregnancy may play some role, but none have been fully confirmed.
During a bowel movement, stool passes from the large intestine into the rectum and then to the anus. The anal nerves help us feel the need to defecate and start muscle activity. The muscles in this area help control when we have a bowel movement.
When you have anal atresia, any of the following can happen.
The anal opening may be narrow, or misplaced in front of where it should be.
There may be a membrane (covering) over the anal opening.
The rectum may not be connected to the anus.
The rectum may be connected to the urinary tract or part of the reproductive system through an opening called a fistula, and no anal opening is present.
Complications and concerns.
Depending on the type and severity of anal atresia, many problems can occur.
When the anal opening is narrowed or misplaced just before its correct position, it may be difficult for the child to defecate, causing constipation and discomfort.
If there is a membrane covering the anal opening, the baby may not be able to have a bowel movement until the membrane is surgically opened.
If the rectum is not connected to the anus and there is no fistula (abnormal connection between the rectum and the urinary tract or vagina) present, there is no passage for stool to leave the intestinal canal. The baby will not be able to pass stool. This leads to intestinal obstruction (stool is trapped in the baby’s body).
When the rectum is not connected to the anus, but a fistula is present, stool can pass through the fistula instead of the anus. This can cause a urinary tract infection.
Risk factors for anal atresia.
Although most children with anal atresia are the only child in their family with the disease, there are some cases where other family members have the disease together.
Associated diseases.
Nearly 50% of children with anal atresia have other abnormal defects. These often include
Spinal deformities such as hemivertebrae, missing vertebrae and spinal cord embolism, renal and urinary tract malformations such as horseshoe kidney and partial duplication of the urinary tract, congenital heart defects, defects and malformations of the trachea and esophagus, limb (especially forearm) defects, Down syndrome, congenital megacolon, and duodenal atresia.
Diagnosis of anal atresia.
After the baby is born, the doctor will check the baby for any problems. When the doctor examines the baby, he or she will check to make sure that the baby’s anus is open and in the right place. If atresia is found, multiple tests will be performed to further clarify the problem and to see if other problems exist.
An abdominal x-ray will give the doctor a picture that shows the general location of the atresia. X-rays also let the doctor know if there are problems with the spine and sacrum (the triangular bone just below the lumbar spine),.
Ultrasound of the abdomen and ultrasound of the spine – These tests are used to look at the urinary tract and spine. They also help the doctor determine if spinal cord tethering (an abnormality in which the ends of the spinal cord are improperly fixed) is present. Spinal cord tethering can lead to neurological problems such as incontinence (uncontrolled bowel movements) and leg weakness as the child grows.
Echocardiography C This test is performed to detect heart defects.
Magnetic resonance imaging/ MRI – In some cases, this test is needed to make a definitive diagnosis of spinal cord tethering or other spinal problems.
Repair of anal atresia.
Treatment recommendations will depend on the type of anal atresia, the presence of associated deformities and their type, and the general health of the child. However, most babies with anal atresia will require surgical treatment.
Recto-perineal malformations.
Babies with recto-perineal malformations require a procedure called anoplasty, which involves moving the anus into a proper position, into having muscles that can control defecation (control of toileting and, in this case, bowel movements).
Colostomy performed in a baby with anal atresia without fistula.
Newborns with anal atresia in boys and girls without fistulas will require one or more surgeries for correction. Colostomy surgery is usually done early.
With a colostomy, the large intestine is divided into two segments, and the ends of the intestine are then passed through small openings in the abdominal wall (the small openings will be in your child’s stomach).
The upper section allows feces to pass through an opening called a stoma and into a collection bag. The mucus coming from the intestine is drained through the opening in the lower section of the intestine.
By performing this procedure, digestion will remain intact and growth will continue until the next surgery is needed. By changing the original route of the stool, there is less risk of infection when the next surgery is completed.
Those nurses and other health care workers who work with your child’s doctor will help you learn how to perform stoma care, and they will help you when you are ready to care for your child at home. Local and national assistance groups may also be very helpful during this time.
The next procedure will create the connection between the rectum and the new anal opening. This procedure is usually performed on the child’s buttocks.
In some cases where the rectum terminates in the abdomen (high lesions), laparoscopic surgery (surgery through a small hole, usually without an incision) or traditional open surgery (surgery through an incision) can be used to bring the rectum down to the anal opening.
After the rectum is lowered to the anal opening, the colostomy will remain in place for six to eight weeks. Stool will continue to leave the body through the stoma until the stoma is surgically closed. The colostomy will have to be left in place so that the new anus heals without infection from stool, and the child will be allowed to undergo a dilation procedure (schedule that includes slowly stretching the anus to the correct size for the child’s age).
After anal atresia surgery.
For several weeks after surgery, the child’s parents are taught to perform anal dilatation to ensure that the anal opening is large enough to allow normal passage of stool.
The colostomy is closed by another surgery at least 6 to 8 weeks later. A few days after surgery, the child begins to pass stool through the rectum (anal opening). Soon after surgery, stools may be more dilute and more frequent than usual. Diaper rash and skin irritation will also be a problem. Your doctor and nurse will help you with the care needed to keep the diaper area healthy.
The stools will be less frequent and a little harder for a few weeks after the procedure. Anal dilation should continue for several weeks or months.
Some infants may become constipated. To avoid this, we encourage a high fiber diet to be given next. Laxatives may be needed before the age of toilet training.
In cases of severe constipation, a bowel treatment program may be needed depending on the specific needs of the child. The program may include educating the child and parents on the use of laxatives, stool softeners, enemas, and bowel training techniques.
Toilet training for children with anal atresia.
Toilet training should begin at a general age, usually around the child’s third birthday. Children with anal atresia are generally slower to gain bowel control and are dependent on the type of deformity and the surgery to repair it, and some children may not be able to gain good bowel control. Each child’s case will be slightly different and will be determined with the help of your doctor.
Long-term outlook.
Children with anal atresia with recto-perineal fistulas usually have good bowel control after surgical repair.
However, children with more difficult types of anorectal malformations may need to participate in a bowel therapy program to help them achieve control of their bowel movements and prevent constipation.
Nurses and other health care professionals who work with your child’s doctor can probably make a plan for your child’s individual needs.