Lower gastrointestinal bleeding refers to blood loss originating from a site distal to the ligament of Treitz. Patients with LGI bleeding present with hematochezia meaning the passage of maroon, bright red blood, or clots per rectum. It is important to remember that 10-15% of cases of bright red blood per rectum have an upper GI source. This is universally a medical emergency.

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Gastroenterology – Lower GI Bleeding: A Practical Approach
Whiteboard Animation Transcript
with Maitreyi Raman, MD
https://medskl.com/Module/Index/lower...

Lower GI bleeds can be a medical emergency as it may represent an upper GI source with rapid transit, and the patient can be hemodynamically unstable, and at high risk of death. It may also be the presenting symptom for colorectal cancer.

When confronted with a patient with a lower GI bleed there are 3 things that are critical:

1. Assess hemodynamic status,
2. Ensure hemodynamic stability through volume resuscitation, and
3. Determining the cause of the bleeding.

The initial focus must involve an assessment of hemodynamic status. Is the patient hypotensive or tachycardic? If “yes” is answered to either of these questions, transfer immediately to the ER for assessment and stabilization.

The next immediate steps should focus on volume resuscitation: insert 2 large bore IV’s, and provide a fluid bolus. Get blood work and remember to type and screen as they may need a transfusion. In addition, assess coagulation status as coagulopathies may need to be reversed.

Once stable – establish the cause of the bleed. An UGI source with rapid transit must be considered. An upper endoscopy is often indicated to rule out an upper GI source in the face of hemodynamic instability.

Up to half of cases of lower GI bleeding is caused by diverticulosis. Diverticulosis is usually painless. Causes of lower GI bleeding associated with pain and cramping include - Ischemic colitis, infectious colitis, and inflammatory bowel disease Hemorrhoidal bleeding is also frequent, and typically occurs with hard stool and constipation. Patients will often complain of blood on the toilet paper after wiping.

Always consider the possibility of colorectal cancer, especially in elderly patients or those with a positive family history. Rarer causes of rectal bleeding include radiation colitis and NSAID colitis. Colonoscopy is often the necessary diagnostic test to confirm the etiology for LGI bleeding, and management strategies should focus on addressing the etiology for the bleed.