What are anorectal malformations?
Anorectal malformations are types of colorectal conditions that comprise a wide spectrum of diseases, which can affect boys and girls, and involve the anus and rectum as well as the urinary and reproductive tract (vagina and uterus in females).
Approximately one in 4,000 children is born with an anorectal malformation. There is a very large spectrum of defects and treatments associated with anorectal malformations.
Anorectal malformations are slightly more common in males versus females.
With an anorectal malformation, several abnormalities can occur, including the following:
- The anal passage may be narrow
- A membrane may be present over the anal opening
- The rectum may not connect to the anus
- The rectum may connect to part of the urinary tract or the reproductive system through a passage called a fistula
What causes anorectal malformations?As a fetus is growing in its mother's uterus before birth, different organ systems are developing and maturing. The lower end of the intestinal tract forms fairly early in pregnancy, generally at 5 to 7 weeks.
In a fetus, the lower portion of the large intestine and the urinary tract start off as one large mass of cells. Certain steps have to take place in the first three months of development in the uterus for the rectum and anus to separate from the urinary tract and form properly. Sometimes, these steps do not occur as they should, and the rectum and/or anus may not develop normally. Nothing that the mother did during pregnancy can be shown to have caused the malformation.
Defects may range from the very minor and easily treated (with an excellent functional prognosis), to those that are complex, with varying diagnoses and treatments that depend on the gender of the child.
How are anorectal malformations diagnosed?Your child's doctor will perform a physical examination when your baby is born, and will look at the anus to see if it is open. Diagnostic imaging tests may be done to further evaluate the problem, such as:
- Abdominal X-rays. Diagnostic test which uses invisible electromagnetic energy beams to produce images of internal tissues, bones, and organs onto film. X-rays may evaluate the presence of air or stool within the newborn’s abdomen, as well as size of intestinal loops.
- Abdominal ultrasound (also called sonography). A diagnostic imaging technique which uses high-frequency sound waves and a computer to create images of blood vessels, tissues, and organs. Ultrasounds are used to view internal organs and to assess blood flow through various vessels.
- Computed tomography scan (also called a CT or CAT scan). A diagnostic imaging procedure that uses a combination of X-rays and computer technology to produce horizontal, or axial, images (often called slices) of the body. A CT scan shows detailed images of any part of the body, including the bones, muscles, fat, and organs. CT scans are more detailed than plain X-rays.
- Magnetic resonance imaging (also called a MRI). A diagnostic procedure that uses a combination of large magnets, radiofrequencies, and a computer to produce detailed images of organs and structures within the body.
- Lower GI (gastrointestinal) series (also called barium enema). A lower GI series is a procedure that examines the rectum, the large intestine, and the lower part of the small intestine. A fluid called barium (a metallic, chalky, liquid used to coat the inside of organs so that they will show up on an X-ray) is given into the rectum as an enema. An X-ray of the abdomen shows strictures (narrowed areas), obstructions (blockages), and other problems.
- Upper GI (gastrointestinal) series (also called barium swallow). Upper GI series is a diagnostic test that examines the organs of the upper part of the digestive system: the esophagus, stomach, and duodenum (the first section of the small intestine). A fluid called barium (a metallic, chalky, liquid used to coat the inside of organs so that they will show up on an X-ray) is swallowed. X-rays are then taken to evaluate the digestive organs.
How are anorectal malformations treated?The treatment of an anorectal malformation may depend on the following:
- The extent of the problem
- The overall health of the child and medical history
- The opinion of the doctors involved in the child's care
- Expectations for the course of the disease
- Your opinion and preference
- Narrow anal passage. Infants who have the type of malformation that causes the anal passage to be narrow may not need an operation. A procedure known as anal dilatation may be done periodically to help stretch the anal muscles so stool can pass through.
- Anal membrane. Infants with this type of opening and will have the membrane removed in surgery. Anal dilatations may need to be done to help with any narrowing of the anal passage that is present, especially during the formation of scarring.
- Lack of rectal/anal connection, with or without a fistula. These infants will need a series of operations in order to have the malformation repaired.
- First, an operation is done to create a colostomy. With a colostomy, the large intestine is divided into two sections and the ends of intestine are brought through openings in the abdomen. The upper section allows stool to pass through the opening (called a stoma) and then into in a collection bag. The lower section allows mucus that is produced by the intestine to pass into a collection bag. By doing a colostomy, the child's digestion will not be impaired and he or she can grow before time for the next operation. Also, when the next operation is done on the lower section of intestine, there will not be any stool present to infect the area.
- The nursing staff and other health care professionals that work with your child's surgeon can help you learn to take care of the colostomy. Local and national support groups may also be of help to you during this time.
- The next operation attaches the rectum to the anus and is usually done within the first few months of life. The colostomies remain in place for a few months after this operation so the area can heal without being infected by stool. (Even though the rectum and anus are now connected, stool will leave the body through the colostomies until they are closed with surgery.) A few weeks after surgery, parents may be performing anal dilatations to help the child get ready for the next phase.
- Two to three months later, an operation is done to close the colostomies. The child is not allowed anything to eat for a few days after surgery while the intestine is healing. Several days after surgery, the child will start passing stools through the rectum. At first, stools will be frequent and loose. Diaper rash and skin irritation can be a problem at this stage. Within a few weeks after surgery, the stools become less frequent and more solid, often causing constipation. Your child's doctor may recommend a high-fiber diet (including fruits, vegetables, juices, whole-wheat grains and cereals, and beans) to help with constipation.
What is the long-term outlook for this disorder?Children who had the type of malformation that involves an anal membrane or a narrow anal passage are usually able to gain good control over their bowel movements after repair of anorectal malformation.
Children with more complex variations of anorectal malformation may have need to participate in a bowel management program in order to help them have control over their bowel movements and prevent constipation.
The nurses and other health care professionals that work with your child's doctors can help tailor a program to your child's needs.