Effective & Trusted Medications Guide

Visceral angiogram

A visceral angiogram is an x-ray study of the blood vessels of the gastrointestinal tract. The doctor (usually a specially trained radiologist) will insert a thin, long catheter into a blood vessel in the groin and, under x-ray guidance, will advance the tip of the catheter into one of the mesenteric arteries (arteries that supply blood to the gastrointestinal tract). Radio-opaque dye then is injected through the catheter and into the mesenteric artery. If there is active bleeding, the dye can be seen leaking into the gastrointestinal tract on the x-ray film. Visceral angiograms are accurate in locating rapid bleeding in the gastrointestinal tract, but it is not useful if the bleeding is slow or has stopped at the time of angiogram.

The visceral angiogram is not widely used because of its potential complications such as kidney damage from the dye, allergic reactions to the dye, and the formation of blood clots in the mesenteric arteries. It is reserved for patients who have severe and continuous bleeding and in whom colonoscopy cannot locate the site of the bleeding.

Blood tests

Blood tests such as a complete blood count (CBC) and iron levels in the blood play no role in locating the site of gastrointestinal bleeding; however, the CBC and blood iron levels may help to determine whether bleeding is acute or chronic, since an anemia (low red blood cell count) associated with iron deficiency suggests chronic bleeding over many weeks to months. Gastrointestinal conditions commonly causing iron deficiency anemia include colon polyps, colon cancers, colon angiodysplasias, and chronic colitis.

When a large amount of blood is lost suddenly as with moderate or severe acute rectal bleeding, the lost blood and red blood cells are replaced by fluid from the body’s tissues. This influx of fluid dilutes the blood and leads to anemia (a reduced concentration of red blood cells). It takes time, however, for the tissue fluid to replace the lost blood within the blood vessels. Therefore, early after a sudden large episode of bleeding, there may be no anemia. It takes many hours and even a day or more for the anemia to develop as tissue fluid slowly dilutes the blood. For this reason, a red blood cell count early after bleeding is not reliable for estimating the severity of the bleeding.

How is rectal bleeding treated?

Treatments for rectal bleeding include 1) correcting the low blood volume and anemia, 2) diagnosing the cause and the location of the bleeding, and 3) stopping active bleeding and preventing rebleeding.

Correcting low blood volume and anemia

Moderate to severe rectal bleeding can cause the loss of enough blood to result in weakness, low blood pressure, dizziness or fainting, and even shock. Patients with these symptoms usually are hospitalized. They need to be quickly treated with intravenous fluids and/or blood transfusions to replace the blood that has been lost so that diagnostic tests such as colonoscopies and angiograms can be performed safely to determine the cause and location of the bleeding.

Patients with severe iron deficiency anemia may need hospitalization for blood transfusions followed by prolonged treatment with oral iron supplements (tablets). Patients with iron deficiency anemia as a result of chronic gastrointestinal blood loss should undergo tests (such as colonoscopy) to determine the cause for the chronic blood loss.

Unless anemia is severe, patients with mild rectal bleeding from colon polyps, colon cancers, anal fissures, and hemorrhoids usually do not need hospitalization. Mild anemia can be treated with oral iron supplements while tests are performed to diagnose the cause of bleeding.

Determining the cause and location of bleeding

Colonoscopy is the most widely used procedure in the diagnosis and treatment of rectal bleeding. Most colonoscopies are performed after administration of oral laxatives to cleanse the bowel of stool, blood, and blood clots. However, in certain emergency situations such as when the bleeding is severe and continuous, a doctor may choose to perform emergency colonoscopy without first cleansing the large bowel. In trained and experienced hands, the risk of either elective (delayed) or urgent colonoscopy is small. (Colon perforation, the most common complication, is rare). The benefits usually far outweigh the potential risks.

Colonoscopy is useful for both diagnosing the cause and determining the location of the bleeding. Locating the site of bleeding is especially important in diverticular bleeding. Even though most diverticular bleeding stops spontaneously without the need for surgery, patients with severe, recurrent, or continuous diverticular bleeding may need surgery to remove the bleeding diverticulum. Since a patient typically has numerous diverticula scattered throughout the colon, colonoscopy may be able to determine which diverticulum is bleeding prior to surgery. Without accurate knowledge of the location of the bleeding diverticulum, the surgeon might have to perform an extensive colon resection (which is not as desirable as removing a small section of the colon) in order to make sure that the bleeding diverticulum is removed.

Nevertheless, colonoscopy has limitations. During colonoscopy doctors may not find active bleeding from a specific diverticulum. He/she may only find a colon filled with blood along with scattered diverticula. In these situations, the diagnosis of diverticular bleeding is assumed if he/she finds no other cause for the bleeding such as colitis or colon cancer. In these situations, there is always some uncertainty about the location of the bleeding. Small, bleeding angiodysplasias also may be difficult to see and may be missed in a colon filled with blood. This is when radionuclide scans and visceral angiograms may be helpful. If the patient starts bleeding again, an urgent, tagged RBC scan followed by a visceral angiogram may demonstrate the location of the bleeding.

Colonoscopy also cannot positively diagnose bleeding from a Meckel’s diverticulum because the colonoscope usually cannot reach the part of the small intestine in which the Meckel’s diverticulum is located. But colonoscopy still can be helpful in establishing the diagnosis of a bleeding Meckel’s diverticulum. Thus, in a young patient with rectal bleeding, a colonoscopy showing a blood filled colon without another source of bleeding, particularly if accompanied by an abnormal Meckel’s scan, makes the diagnosis of Meckel’s diverticulum bleeding highly likely. Surgical resection of the Meckel’s diverticulum should result in permanent cure with no recurrence of bleeding.