Is passing blood after bariatric surgery normal?

Conditions Expert Dr. Otis Brawley Chief Medical Officer,
American Cancer Society

Expert Answer:

I will talk a bit about bariatric surgery, but first let me say that bright red blood in the bowels is always something that should be seen by a physician or capable health-care provider very quickly. I believe significant blood merits a trip to the emergency room, even in the middle of the night. Sustained small amounts of bright red blood need to be assessed within the next several days. Intermittent bleeding should be assessed within the week. This needs to be addressed quickly, as large amounts of blood can be lost, leading to weakness and fatigue or even loss of consciousness and worse.

The most common cause of bright red blood per rectum is a non-serious condition, bleeding hemorrhoids. This is easily diagnosed. There are external hemorrhoids that can be easily seen and internal hemorrhoids that require a scoping procedure to see and diagnose. Other causes of bright red blood in stool are polyps in the colon, diverticula (a weakening in colonic wall), inflammatory bowel diseases such as ulcerative colitis and Crohn's disease, or colon cancer. An uncommon but seen complication of some types of bariatric surgery is gastric and duodenal ulcers. These ulcers can bleed, but the blood is usually digested, causing the stool to be black. Bright red blood in stool generally means it is from the colon.

There are several kinds of bariatric surgery. These are procedures to decrease the size of the stomach. Decreasing the size of the stomach creates a feeling of satiety or fullness of the stomach earlier. It lowers the limit on how much food one can eat at one time. Some gastric bypass operations are also designed to pass food through a shorter part of bowel so that fewer calories are absorbed.

These procedures, when incorporated with a bariatric diet, often cause loss of more than half of one's excess weight. Candidates are typically people with moderate to severe obesity and a disease related to the obesity, such as diabetes, hypertension or sleep apnea. Significant gastroesophageal reflux disease due to obesity can also be treated with some bariatric procedures.

All the bariatric surgeries run a risk of side effects. During the period of weight loss (the first six months), a significant proportion of patients will have mood changes and body aches, feel tired or flu-like, feel cold and have dry skin and hair loss.

The most common long-term side effects are vitamin deficiencies and malnutrition. We especially see deficiencies of iron, vitamin B12, vitamin D and folate.

Less-common complications include hypoglycemia, dehydration, gallstones, kidney stones and bleeding stomach ulcers.

A few folks who get certain operations such as the gastric bypass are at risk for "dumping syndrome." Food moves too quickly through the bowels, leading to nausea and vomiting, diarrhea, dizziness and sweating. Most who get this relate it to eating very high-fat foods or very sweet foods.

It is possible for someone with a dumping syndrome who has eaten red foods such as tomatoes, red peppers or raspberries to have a red residue in their stool that could be mistaken as blood. A physician would do a laboratory test to confirm that the red is blood.