[1] Melena is four-times more likely to come from an upper gastrointestinal bleed than from the lower GI tract; however, it can also occur in either the duodenum and jejunum, and occasionally the portions of the small intestine and proximal colon.

Lower gastrointestinal series evaluation can be performed with anoscopy, flexible sigmoidoscopy, colonoscopy, rarely barium enema, and various radiologic studies.

[6] The history in these patients should focus on factors that could be associated with potential causes: blood coating the stool suggests hemorrhoidal bleeding while blood mixed in the stool implies a more proximal source; bloody diarrhea and tenesmus is associated with inflammatory bowel disease while bloody diarrhea with fever and abdominal pain especially with recent travel history suggests infectious colitis; pain with defecation occurs with hemorrhoids and anal fissure; change in stool caliber and weight loss is concerning for colon cancer; abdominal pain can be associated with inflammatory bowel disease, infectious colitis, or ischemic colitis; painless bleeding is characteristic of diverticular bleeding, arteriovenous malformation (AVM), and radiation proctitis; nonsteroidal anti-inflammatory drug (NSAID) use is a risk factor for diverticular bleeding and NSAID-induced colonic ulcer; and recent colonoscopy with polypectomy suggests postpolypectomy bleeding.

The full effect of vitamin K is not obtained for 12–24 hours, unlike fresh frozen plasma which immediately reverses clotting abnormalities.

The effects of fresh frozen plasma last about 3–5 hours and large volumes (> 2–3 L) may be required to completely reverse clotting abnormalities, depending on the initial prothrombin time.

Evidence of possible benefit in patients with cirrhosis and GI bleeding has been demonstrated, although the optimal dose is unclear and recombinant activated factor VII is very expensive.

The role of anoscopy and flexible sigmoidoscopy in inpatients with acute lower GI bleeding is limited, as most patients should undergo colonoscopy.

[citation needed] Colonoscopy is the test of choice in the majority of patients with acute Lower GI bleeding as it can be both diagnostic and therapeutic.

[2][10] If a patient is suspected of having severe blood loss they will most likely be placed on a vital sign monitor and administered oxygen either by nasal cannula or simple face mask.

[2] Individuals at high risk of another heart attack but not meeting the above criteria should continue their aspirin during the LGIB event but stop the other antiplatelet medication for 1–7 days following cessation of the bleed.

One recent study identified poor kidney function (creatinine > 150 μm), age over 60 years, abnormal haemodynamic parameters on presentation (low blood pressure) and persistent bleeding within the first 24 hours as risk factors for worse outcome.

[2] It is most likely that a surgical consult will be ordered if the patient is unable to be stabilized by non-invasive techniques, or if a perforation is found that requires surgery (e.g., subtotal removal of the colon).