Small Bowel Obstruction

What is it?

Normally, the muscular small intestine contracts to move air, fluid, and food through, but with small bowel obstruction, the small intestine does not work as it should and these things can get stuck. The small intestine may be partly or completely blocked. If totally blocked, this can lead to problems such as swelling because of the trapped material. As a result of the swelling, the intestine cannot absorb as it typically does and this can cause dehydration and eventual kidney failure. The intestine wall can also tear, allowing the fluid inside the intestine to leak out leading to infection. The blood supply to the intestine is also impacted with the obstruction and without blood, parts of the intestine can die.

Why does it happen?

Adhesions, or scars inside your abdomen after surgery can press on the intestine
Tumors from in or outside the intestine
Hernias. This is when an organ or tissue pokes through a weak part of muscle or tissue that usually keeps it in place. The intestine may also move through and get trapped and stuck
Narrowing of the intestine (stricture). This can be caused by disorders such as Crohn’s disease, medications, previous radiation therapy, lack of blood supply, or tumors
Twisting of the intestine itself
Trauma. Usually, the jejunum, the second part of the small intestine is affected because it is in the back of the abdominal cavity and can be pressed between the vertebral column.
There are also other rare causes

Regardless of the cause, there is a blockage in the small intestine that does not allow food to pass through leading to swelling as secretions and food cannot continue to move through the GI tract. Also, swallowed air collects and bacteria begins to populate and grow and start breaking down food in the small intestine leading to extra gas. The swelling continues and the intestine no longer can absorb as it usually does and actually secretion into the intestine increases. This can lead to dehydration. With continued swelling, the pressure may be great enough to cause blood to not be able to flow to the intestine.

What are the symptoms?

This depends on where the blockage is and how much is blocked. But, because of the blockage, the small intestine and stomach before the obstruction will swell. Symptoms may include:

Dehydration. The normal function of the small intestine is to absorb the liquid and food we eat.
Abdominal pain, usually crampy in nature, may come in waves every several minutes
Swelling and bloating of the abdomen. It may feel hard to the touch.
Nausea
Vomiting
Inability to pass a bowel movement or gas. It takes 12-24 hours for the colon to completely empty after the onset of obstruction.

How is it diagnosed?

Blood tests to evaluate the level of dehydration and pictures of your abdomen. This may include x-rays or a CT scan.

You will be monitored frequently to make sure there are no signs that the intestine’s blood supply is cut off (strangulation). This is possible if the intestine swells and if blood flow is not restored, the intestine can die and lead to many problems.

How is it treated?

In the hospital, you will be given fluids through an IV and your urine output will be monitored to make sure you are not dehydrated. A nasogastric (NG) tube may be placed. This is a small tube placed down your nose, through your throat, and into your stomach to suck up fluid. Not only may this reduce vomiting by clearing the stomach of fluid and air, it may also improve your comfort level. If your intestine is only partway blocked, you may need no treatment and it will get better on its own. Sometimes people will need surgery; this often happens if you do not improve after a period of observation, if you never have had abdominal surgery, or if closed-loop (the intestine can be obstructed in two locations so there is no outlet from the front or end), or strangulation is suspected. Surgery will remove the blockage and any parts of the intestine that are dead. After the dead part is removed, either the healthy tissue will be reconnected or if this cannot be done right away, part of your intestine will be connected to a stoma (small hole on your abdominal wall), and a bag will be attached to your skin. A surgery may then be performed later to reattach the two portions of the intestine.

When the obstruction is resolved, typically there is decreased distension of the abdomen, you will pass stool or gas and the NG tube will have less output. If the obstruction has clearly resolved, the NG tube can be removed.