Small Intestine Atresia and Stenosis
The digestive tract is a very long, coiling tube that starts at the mouth and ends at the anus. The main parts of the digestive tract are the mouth, the esophagus, the stomach, the small intestine, the colon and the anus. The small intestine is responsible for most of the digestion and the absorption of the nutrients from the food that is eaten. The small intestine has three segments. The first segment, the duodenum, is connected to the stomach. The second segment is the jejunum and the final segment, the ileum, connects to the colon, also known as the large intestine.
Small intestine atresia (SIA) means that there is a complete blockage or interruption somewhere in the course of the small intestine. Small intestine stenosis (SIS) means that there is a narrowing of the passage within the small intestine. Both of these conditions either completely block or significantly impede the passage of food through the digestive tract. Either situation makes it very difficult or impossible to digest food, absorb nutrients and eliminate waste through the large intestine. An interruption, blockage or narrowing of the small intestine may occur anywhere along its length.
Most of the time, SIA is not believed to be familial. In the instances where a recurrence has been reported within a family, the pattern of inheritance suggests autosomal recessive inheritance.
Few studies have investigated the prevalence (how often the condition occurs) of small intestine atresia or stenosis. Of those that have, the prevalence of an atresia or stenosis has been reported to be from 1.3 to 2.9 per 10,000 live births. In the published medical literature, there is quite a bit of variation in the estimated prevalence rates. Recently, a large population-based study using information from several European birth defects registries estimated the prevalence of any type of SIA to be 1.6 per 10,000 live births; duodenal atresia at 0.9 per 10,000 live births; and jejuno-ileal atresia at 0.7 per 10,000 live births. Males and females are affected in equal numbers.
Common Associated Conditions
According to the large, European population-based study, 20.6% of any type of small intestine atresia or stenosis was associated with a chromosomal disorder. Of the individuals with SIA of any type who were single babies (not part of a twin, triplet or other multiple pregnancy), about a quarter (26.7%) had another major birth defect in addition to the SIA. Additional body systems that were observed to be affected included cardiac, craniofacial, digestive (in addition to the SIA), and urinary systems, and limbs.
Short-Term Treatment and Outcomes
In the short term, the first order of business involves surgery to open up or reconnect the small intestine so the digestive tract can process, absorb nutrients, and allow the passage of food. Following surgery, the digestive tract has to be allowed to heal and be slowly trained to process and move food along its passage. This process may take many days or even weeks. If other birth defects are present, these may need to be repaired at this time, also.
Long-term Treatment and Outcomes
Long-term treatment and outcome depend on several factors. In some cases, the small intestine is greatly shortened and this is likely to result in a digestive tract that doesn't work well to digest and absorb nutrients. This is called short bowel syndrome and it may make recovery more complicated and make recovery take longer. Recently, a surgical procedure called serial transverse enteroplasty (STEP) procedure has been developed that works to lengthen the short intestine.
In the case of SIA in a baby with a chromosomal or other genetic condition, other issues may be present and, based on what other problems are either known or suspected, an individualized treatment plan will need to be developed and carried out. If another body system is involved, there may or may not need to be interventions to repair this body system at or close to the same time that the small intestine is repaired.
Complications can occur after surgery as the intestine and incisions heal. If a fever develops that is higher than 101 Fahrenheit or if the incision begins to look red and swollen or infected, it may signal that an infection is developing. If vomiting continues or the baby is not starting to eat normally, this needs to be evaluated by the baby's care team. Lastly, if it seems as if the baby is not urinating as much or as often as usual, it may be that he is not absorbing enough water and is becoming dehydrated. This will be evident if she is not wetting her diapers as often as usual.
Potential Effects on Children's Development
If the SIA is an isolated finding (there are no other medical issues and it is not a feature of a syndrome or more complex condition) it is very possible that the baby's development will not be greatly impacted. There is a likelihood that developmental delay or intellectual disability could be a part of a spectrum of features (e.g. a syndrome). If there is reason to suspect that the baby has a chromosomal or genetic condition or other body systems are affected, then development may also be affected. In any case, following up with care providers and screening the baby for developmental milestones can often rule out these concerns. If there are developmental delays, identifying and characterizing them as early as possible may help to guide interventions that will help assure the best outcomes possible.