Rectal and Large Intestinal Atresia / Stenosis (also called anal atresia)
Rectal and large intestinal atresia or stenosis is the term used to describe a group of rare congenital conditions of the lower gastro-intestinal tract (bowel). It can range from absence of these structures to malformations of the anus and rectum (called colon, rectum or anal atresia). If these lower gastrointestinal structures are present but only partially open to the passage of stool the condition is called colon/rectum/anal stenosis. In anal stenosis, the anus will look normal externally but it will not be connected to the bowel.
Another variation of the condition is called imperforate anus, where internal structures are normal but the anus is closed over with skin. Babies may have small tube-like openings (called fistulas) from the bowel that open onto the skin of the perineum or that drain into the vagina or urethra. These various abnormalities may be low (in which case the nerves and muscles will be correctly formed but skin covers the anal opening). Other times the atresia or stenosis is higher in the pelvis; if high, nerves may be malformed and muscle structures can be affected.
Imperforate anus is usually discovered during the baby's newborn examination. The baby will have an unusual appearing anus coupled with abdominal distention, as the baby is unable to pass meconium (the first stool after birth, dark and sticky in consistency). Anal stenosis may not be immediately discovered but symptoms such as abdominal distention and poor feeding will be noticed soon after birth.
During early fetal life the bowel and surrounding structures may fail to develop, perhaps due to lack of blood supply to that area of the body. These conditions are sometimes detected before birth because of polyhydramnios (excess amniotic fluid). The cause is unknown. In some families, there is a hereditary pattern of several members having the condition, but this is not often the case. Maternal diabetes as well as prenatal alcohol use may be related to this disorder.
Anal atresia or stenosis occurs in about 3 of 10,000 live births, with slightly more males affected. Imperforate anus occurs in 1 of 5000 live births. Our program has been tracking rectal and large intestinal atresia/stenosis among live births in select counties since 2005 and are gradually expanding statewide.
- Using data from births to Hennepin and Ramsey county residents between 2012-2016, we found that 3.6 babies were born with rectal and large intestinal atresia/stenosis per 10,000 births.
- Using this data, we estimate about 24 babies are born with rectal and large intestinal atresia/stenosis every year in Minnesota.
Parental education and support are essential, and local, regional and national organizations may be very helpful.