GI Bleeding

The gastrointestinal tract is a common source of blood loss, and you will undoubtedly work with patients who need workup for GI bleeding. We've collected some of the fundamental facts that you should know about the subject - this should not be considered an exhaustive source on the topic, but it may be useful as an introduction or as a reference on the subject. It may also be worthwhile to review the abdominal exam page.

 

Anatomy

Bleeding in the GI tract can arise from any source along its course. This includes:

The esophagus can be supplied by many arteries (with much individual variation), including small aortic feeders, the left bronchial artery, the inferior thyroid, the inferior phrenic, the celiac trunk, and splenic, and the short gastric arteries. The stomach is supplied by the gastric artery and celiac artery. The small intestine is supplied by the celiac artery. The appendix, ascending colon (right colon), and half of the transverse colon are supplied by the SMA (superior mesenteric artery, a branch of the aorta). The distal transverse, descending, sigmoid and rectum supplied by IMA (inferior mesenteric artery, also off the aorta).

Upper vs. Lower

The first step in evaluating a GI bleed is determining if the source is upper GI or lower GI. "Upper" refers to anything above the ligament of Treitz, which separates the 4th part of the duodenum from the jejunum. Obviously, lower GI refers to anything in the jejunum or beyond. It's estimated that about 95% of GI bleeds occur either above the ligament of Treitz or below the ileocecal valve (ie in the large intestine), which is convenient for gastroenterologists - these are the same areas that can be explored with either a gastroscope or colonoscope.

You may suspect an upper source if there is:

  1. hematemesis or coffee-ground emesis
  2. melena
  3. an elevated BUN with no other clear explanation
  4. hemodynamic instability (much less often a problem as an immediate consequence of a colonic bleed) even without other evidence of an upper source
  5. a background of cirrhosis or active alcohol intake

Hints that the source is more likely lower:

  1. bright red blood per rectum, or maroon stool (hematochezia)
  2. occult blood loss
  3. crampy lower abdominal pain
  4. tenesmus
  5. risk factors for ischemic colitis (ASCVD)

By history, upper GI often accompanied by vomiting of "coffee-ground" material, &/or passage of melena, which is blood that has been digested and passed out the anus. It tends to be dark red to black, has a sticky or tar-like consistency, and has a distinctive pungent odor. If blood flow or intestinal motility is brisk, blood will not be fully digested, and may appear fresh and bright red on passage. The first diagnostic test to help narrow the diagnosis is simple placement of an NG (nasogastric) tube to wall suction, or irrigated with tap water. If the source of the bleed is upper, frank blood, clots, or coffee-ground material will often be suctioned. Be aware that a negative aspirate does NOT rule out upper GI bleed. This test can be followed by EGD (esophagogastroduodenoscopy - endoscopy of the GI tract from mouth to duodenum) for confirmation that there is a currently bleeding upper source (or not).

Lower GI bleeding is assumed if the initial upper GI workup is negative, or if the presentation clearly suggests a lower GI source. Digital rectal exam (DRE) is often performed, although recent studies cast doubt on its diagnostic utility. Note if stool is tarry (black - melanotic, suggesting and upper GI source), blood streaked (suggesting lower GI source, including hemorrhoids), bright red (suggesting either briskly passed upper bleed vs. lower bleed), or maroon, suggesting a proximal colonic bleed, such as you would see with an AV malformation in the ascending colon or cecum. 

Colonoscopy is often performed as the initial invasive examination. However, if bleeding is brisk, a nuclear tagged RBC GI bleed scan may be performed as the initial examination. In this test, radiolabeled red blood cells are injected into the patient's circulation, and the patient is observed by a device that can detect these cells if they are in sufficient concentrations. If blood is collecting in the patient as a result of a bleed, the area of collection is highlighted on the scan. The procedure takes about 1 hour. If the scan is positive, it can be followed by a selective arteriogram to localize and identify the etiology of the bleed.

Causes of upper GI bleed include:

Of these causes, nearly 90% of upper GI bleeds are caused by 4 factors: peptic ulcers (gastric or duodenal), gastritis, esophagogastric varices, and Mallory-Weiss tear.

Causes of lower GI bleed include:

Of these causes, the most common are anorectal lesions such as those caused by internal hemorrhoids, anal fissures, or local trauma. In older populations or patients with chronic renal failure, AVM (arterio-venous malformation) is very common.

 

Diagnosis

Begin with history and physical exam. History must include:

Physical exam should include:

Initial labs should include:

HCT and Hgb may remain elevated in the initial stages of a bleed, as volume will not yet be repleted - hemagram should be repeated q6 hours while bleeding continues. A BUN:Creat ratio of >30 suggests that an upper GI bleed has occurred or is occurring. INR and PTT may reveal an existing coagulopathy - which may be highlighted by abnormal LFT's. In other words, you need to search for the underlying cause of the coagulopathy, and a common reason is hepatic dysfunction or biliary obstruction (remember that the liver produces the majority of the clotting factors that circulate in the blood).

Many authorities also recommend an initial EKG to rule out MI, as ischemia 2o "silent" MI can be a cause of GI bleeding. Finally, chest x-ray and abdominal x-ray (or CT) may be appropriate - both are useful for assessing fluid (blood) in body cavities, as well as possibly picking up cancerous foci.

Treatment

Initial intervention must include rapid assessment of hematologic status - is the patient volume depleted, is HCT dangerously low? Saline or other isotonic fluid should be started, and blood products should be given if HCT <24 or Hgb <8.5 and if bleeding is still continuing. Recent evidence supports not giving blood products if bleeding has stopped, the underlying cause can be fixed, and the low HCT doesn't pose a risk to the patient otherwise (as it would in a patient with cardiac disease, for example). 

O2 is also useful in patients with low HCT or Hgb, as they have limited ability to transport the oxygen they do inhale. Coagulopathy should be corrected. If NSAIDS have recently been used, consider platelets or FFP. If coumadin (warfarin) has been used, consider vitamin K &/or FFP. Heparin can be reversed with protamine, although simply discontinuing heparin infusion is often sufficient.

Different sources of bleeding are treated differently. Ulcers in the stomach or duodenum can be cauterized via EGD, or injected with saline &/or epinephrine. Esophageal varices can be controlled with rubber band ligation or injection sclerotherapy. AVM's can be cauterized. Other small intestinal bleeds are often treated with either angiographic intervention (such as embolization), with endoscopic cauterization, or with surgery. 

Large bowel bleeds can also be treated surgically or with angiographic intervention, or with colonoscopic intervention. AVM's can be cauterized, polyps can be removed by snare electrocautery or with a hot biopsy forceps, and internal hemorrhoids can be managed with diet, sitz baths, topical steroids, rubber band ligation, or surgical resection.