Lower GI Disease
Small Bowel
The small bowel is the largest and longest part of the GI tract. Its main function is to mix up food with enzymes, which promotes the breakdown of food into molecules that can easily be absorbed into the blood stream.
In scleroderma, a person can have poor motility (propulsion of food particles). This can lead to interference with the food absorption process. It can result in bringing fluid into the gut and can cause diarrhea. The flushing action of the small bowel is also affected, which means that bacteria can find pools of stagnant fluids to grow in. This leads to a condition called small intestinal bacterial overgrowth (SIBO).
All of this together can cause bloating, distention, diarrhea, malabsorption, and in severe cases, malnutrition.
There are many ways to potentially treat the dysmotility and will vary from patient to patient; overall, prokinetics, or stimulants of motility, are the common choice. For all people with scleroderma, however, SIBO is treated with rotating antibiotics.
Large Bowel
Complications in the large bowel affect the colon and the rectum. The colon is much more passive than the small bowel or stomach. It goes into active movement once or twice a day when it pushes stool from the right side to the left side. Typically, when the stool moves to the left side, it sits in the rectum and is stored there until you are ready for a bowel movement.
In scleroderma, the motility in the colon is affected. It is unable to push stool towards the rectum as it should, becomes dilated, and then forms diverticula (bulging pouches in the lining of your colon) which causes problems with pooling of fluid or stool.
Overall, these complications in the large bowel can lead to constipation.
Treating the large bowel typically looks like treating constipation. There are two broad categories of treatment. One uses osmotically active agents; they pull water from our body into the colon to soften the stool. However, this may not always be a good option for people with scleroderma if they have small bowel disease with increased water content. The other option is to use drugs that stimulate the colon to have more motility.
At the bottom of the GI tract is the anal sphincter, which is made up of an internal component and external component. Some people with scleroderma will have some atrophy or weakness of the internal anal sphincter, which is important for maintaining continence.