The clot most often forms in a vein called the "superior mesenteric vein," close to the small intestine. It's one of a number of things that can suddenly lessen blood flow to the intestines, a condition your doctor might call acute mesenteric ischemia.
Symptoms for low blood flow to the intestines tend to be similar whether a venous thrombosis causes it, or something else.
When you have low blood flow to your intestines, the main symptom is pain, especially dull pain around the belly button area. This usually comes on quickly, but it can sometimes develop slowly over weeks or months.
Unlike other problems in your belly, like appendicitis or diverticulitis, the pain doesn't increase greatly when you or your doctor pushes on it. But this may change as the condition develops and tissue in your gut starts to die (necrosis).
In some cases, you might not notice any symptoms with MVT, especially at first.
Other conditions you have seem to trigger MVT in more than 80% of cases. These might include:
- Inflammatory bowel disease (IBD), such as Crohn's disease and ulcerative colitis.
- Infection in your belly area like an abscess, appendicitis, or diverticulitis.
- Sickle cell disease or another condition that makes your blood clot too easily.
- Injury to a blood vessel from an accident or surgery.
- Laparoscopic surgery that raises pressure in your belly.
- Pancreatitis (inflamed pancreas).
- Tumor that pushes on your vein or releases certain substances that cause unnecessary clotting.
- Liver disease (cirrhosis) that causes a buildup of fluid and pressure in the vein that connects the liver to the intestines.
- Decompression sickness, a condition divers get when they rise too quickly from deep water.
MVT can look like other conditions. Your doctor will ask about your symptoms and examine you, especially your belly area. They may take pictures of the inside of your body with imaging tests such as:
Your doctor will look at the images for signs of swelling in the intestines and blockages in the blood vessels around your intestines.
It's important to start treatment right away when MVT causes sudden blood loss to the intestines because it can lead to a serious condition where bowel tissue starts to die
If it seems clear you have acute mesenteric ischemia or your belly is very tender, your doctor might send you straight to surgery either for treatment or to check your abdomen for problems (exploratory surgery).
Your doctor will likely start you right away on anticoagulant medications, which help stop blood clots from forming and building up. These include:
- Unfractionated heparin (typically given in the hospital)
- Low molecular weight heparin
- Vitamin K antagonists
- Novel oral anticoagulants (NOAC)
You will likely continue on these medications for 3 to 6 months, or longer if your doctor finds that you have a chronic condition that makes your blood clot too easily.
When it's clear that MVT has cut off blood to your intestines or that tissue in your bowel has started to die, you will go straight to surgery to stop it.
In some cases, doctors may be able to push a small tube, or catheter, through a vein and stretch the blood vessel with a balloon so that blood can get through or the clot can pass.