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Rectal Bleeding and Anal Bleeding

The spontaneous remission rate for lower gastrointestinal bleeding, even with massive bleeding, is 80% (the same as for upper gastrointestinal bleeding). No source of bleeding can be identified in 12%, and bleeding is recurrent in 25%. Bleeding has usually ceased by the time the patient presents to with  hematochezia and anal bleeding.

Initial Clinical Evaluation of Rectal Bleeding

The severity of rectal blood loss and hemodynamic status should be assessed immediately. Initial management consists of resuscitation with colloidal solutions (hetastarch [Hespan]) or crystalloid solutions (lactated Ringers solution) and blood products if necessary. The source of bleeding should be sought while the patient is being resuscitated.

The duration and quantity of bleeding are assessed; however, the duration of rectal bleeding is often underestimated and the quantity is often overestimated.

Risk factors for rectal bleeding that may have contributed to the bleeding should be assessed, such as the use of nonsteroidal anti-inflammatory drugs, anticoagulants, history of colonic diverticulosis, renal failure, coagulopathy, colonic polyps or hemorrhoids.

Patients may have a history of hemorrhoids, diverticulosis, inflammatory bowel disease, peptic ulcer, gastritis, cirrhosis, or esophageal varices.

Hematochezia. Bright red or maroon blood per rectum suggests a lower GI source; however, 11-20% of patients with an upper GI bleed will have hematochezia as a result of rapid blood loss.

Melena. Sticky, black, foul-smelling stools suggest a source proximal to the ligament of Treitz, but it can also result from bleeding in the small intestine or proximal colon.

Malignancy may be indicated by a change in stool caliber, anorexia, weight loss and malaise.

Associated Findings

Abdominal pain may result from ischemic bowel, inflammatory bowel disease, or a ruptured aortic aneurysm.

Bloody diarrhea suggests inflammatory bowel disease or an infectious origin.

Bleeding with rectal pain is seen with anal fissures, hemorrhoids, and rectal ulcers.

Chronic constipation suggests hemorrhoidal bleeding. New onset constipation or thin stools suggests a left-sided colonic malignancy.

Blood on the toilet paper or dripping into the toilet water after a bowel movement suggests a perianal source.

Blood coating the outside of stool suggests a lesion in the anal canal.

Blood streaking or mixed in with the stool may result from a polyp or malignancy in the descending colon.

Maroon colored stools often indicate small bowel and proximal colon bleeding.

Physical Examination

Postural Hypotension suggests a 20% blood volume loss; whereas, overt signs of shock (pallor, hypotension.