Lower GI bleeding is often a disease of the elderly which may be life-threatening in this vulnerable population with multiple co-morbidities.  The topic is broad and includes many etiologies of bleeding distal to the ligament of Treitz.  Unlike upper GI bleeds which are often clearly identified on advanced diagnostics, up to 50% of lower GI bleeding sources are never identified.  From time spent working in the ICU and doing follow-up chart review on lower GI bleed admissions, I am not surprised that 80% of lower GI bleeds resolve without specific intervention, requiring only supportive care and careful hemodynamic monitoring.  What may appear (and smell) impressive in the ED does not always require emergent intervention, yet understanding how to determine the severity of bleeding, need for aggressive resuscitation, and diagnostic/consultant resources are key for the emergency provider.

When assessing the critically ill patient with likely lower GI bleed, if possible gather information on recent procedures such as colonoscopy or aortic grafting.  Careful review of medications is high yield, as elderly patients with lower GI bleeds are often on novel anti-coagulants or Coumadin that may require reversal.  The physical exam is more helpful in lower GI bleed than upper GI bleed, as rectal examination may give clues to briskness of bleeding and confirm that bleeding is not from a GU source such as hematuria or vaginal bleeding.  Anoscopy is an easy and quick bedside test to look for internal hemorrhoids. 

Imaging can be confusing in the setting of lower GI bleeding.  There are multiple modalities, but I feel CTA is the most time efficient study for the emergency physician and localizes bleeding that exceeds 0.5cc/min.  Tagged RBC scans are difficult to arrange, more time intensive, although are able to detect 0.1 cc/min of bleeding (and can detect a minimum of 3 cc of pooled blood if bleeding is not active).

As with upper GI bleeding, the primary treatment involves resuscitation and ABC’s with focus on circulatory support via initial crystalloid and then blood products.  Any coagulopathy should be corrected quickly.  The secondary treatment with lower GI bleeding aims to determine the source of bleeding and stop the bleeding – it is important to know the resources available at your emergency department. 

-Flexible sigmoidoscopy, colonoscopy: may identify source and allow use of endoscopic hemostasis techniques (injection sclerotherapy, electrocoagulation, heater probe therapy, banding, and clipping)

-Interventional radiology for embolization

-Surgical intervention (up to 5% of lower GI bleeds require emergent surgery)

Consider NG tube or upper endoscopy to look for brisk upper GI bleed, as hematochezia originates from an upper GI source 10-14% of the time.

References:

“Lower Gastrointestinal Bleeding.”  Tintinalli's Emergency Medicine: A Comprehensive Study

Guide, 7e, Chapter 79