In short bowel syndrome, bowel is another word for the intestines.
It’s a condition that occurs when either the small intestine and/or the large intestine
become physically shorter when a portion is removed by surgery, or functionally shorter,
when a portion is damaged in a way that makes it nonfunctional.
This can lead to poor absorption of water and vital nutrients from food.
Normally, digestion begins when food is chewed and travels into the stomach where it’s
dissolved by stomach acid, enzymes, and physical churning.
Then, it’s sent to the first portion of the small intestine, which is called the duodenum.
This is where more enzymes are added from the pancreas to digest macronutrients, including
proteins, carbohydrates, and fats, while bile is added from the liver and gallbladder to
help absorb fats.
It’s also where the absorption of some minerals like calcium, iron, and magnesium begins.
The next section is called the jejunum, and it has long projections on its surface, giving
it a large surface area for absorption.
It plays the biggest role in the digestion and absorption of most nutrients, including
the breakdown-products of macronutrients, zinc, water-soluble vitamins, and fat soluble
vitamins, namely A, D, E, and K.
The third section is called the ileum, and it has tight intercellular junctions, allowing
it to efficiently absorb fluid and begin concentrating the intestinal contents.
Unlike the jejunum, the ileum is also capable of undergoing structural and functional adaptations
to compensate for the jejunum if needed.
The final portion is called the terminal ileum, and it absorbs vitamin B12 and bile salts
which are recycled.
It ends with the ileocecal valve, which prevents intestinal contents from going into the large
intestine too quickly and the backward flow of material.
The large intestine functions to absorb water, electrolytes like sodium and potassium, short-chain
fatty acids, and bacteria within it produce vitamin K.
Since each part of the small intestine has a specialized function, as does the large
intestine, the manifestations of short bowel syndrome depend on which portion is no longer
functioning normally.
Diarrhea can result from intestinal contents moving too quickly or from food intolerances
due to loss of certain enzymes.
This can lead to life-threatening dehydration.
An inability to absorb certain vitamins and minerals can lead to a large range of signs
and symptoms, while malabsorption of macronutrients leads to malnutrition and weight loss.
Short bowel syndrome can be present at birth, but typically occurs when part of the small
bowel is removed during surgery.
Common conditions requiring this include necrotizing enterocolitis in babies, and Crohn’s disease
in adults.
Any condition that injures the small intestine and makes part of it nonfunctional can cause
the condition even if the intestinal length is normal.
Diagnosis includes the medical history, lab tests looking for nutritional or electrolyte
deficiencies or a resulting anemia, imaging such as an abdominal X-ray, barium studies,
or MRI, and endoscopy of the upper and lower intestines.
Treatment depends on the symptoms.
Mild cases may require dietary adjustments with slowly increasing food and water intake,
supplements, and diarrhea medications.
Severe cases may include total parenteral nutrition, or TPN, which provides intravenous
nutrition and fluids, and an eventual small bowel transplant.
All right, as a quick recap...Short bowel syndrome occurs when either the small intestine
and/or the large intestine become physically or functionally shorter.
This leads to malabsorption of water and nutrients, and can cause a wide variety of symptoms depending
on the section of bowel involved.
Diagnosis depends on the medical history, lab tests, and abdominal imaging, while treatment
may include dietary adjustments, diarrhea medications, and TPN.