Guideline Update - Management of Acute Lower Gastrointestinal Bleeding

Educational Objective:

Cite recent guideline changes for managing the early stages of an acute lower gastrointestinal bleed in a borderline stable patient.

Key Point:

Some of the recommendations in the 2023 ACG guideline on acute lower gastrointestinal bleeding depart significantly from the (now outdated) 2016 guidelines:

New (2023): “We suggest performing a CT angiography (CTA) as the initial test in patients with ongoing, hemodynamically significant hematochezia (conditional recommendation, low-quality evidence).”

Old (2016): “Colonoscopy should be the initial diagnostic procedure for nearly all patients presenting with acute LGIB (strong recommendation, low-quality evidence).”

Explanation:

CTA plays an increasing role in the diagnosis (90% sensitivity, 92% specificity) and management of LGIB specifically because of its ability to rapidly obtain images without the need for a bowel preparation. In addition, multiphase CTA can be typically completed within minutes, even in hemodynamically unstable patients.

It can furthermore precisely localize the source of both arterial and venous bleeding in upper as well as lower GIB, which is especially helpful in patients with significant hematochezia (the above patient) because hematochezia is a symptom shared by both upper and lower GI bleeds.

Finally, a CTA may delineate the vascular anatomy, which facilitates radiographic embolization. 

Patients with a negative CTA often benefit from a conservative wait and see strategy and can be spared enduring an endoscopic procedure. In a retrospective study of patients undergoing CTA for LGIB, nearly 80% of patients with a negative CTA had no further clinical or radiologic evidence of rebleeding and settled spontaneously without the need for endoscopic or radiologic intervention.

Patient factors associated with a positive CTA include recent bowel resection or endoscopic intervention, transfusion of more than 3 units of PRBC per day, use of anti- platelet agents, tachycardia, and hypotension. In addition, obtaining a CTA within 4 hours of hematochezia onset increases the likelihood of a positive test.

CTA is not useful in patients with minor bleeds or in whom the bleeding has clinically subsided because the rate of bleeding is usually too low to be detectable on a CTA.

Other points:

The 2016 guidelines recommend a specific red blood cell to platelet transfusion ratio for patients requiring massive transfusions. By contrast, the 2023 guidelines no longer discuss algorithms for massive transfusions, but instead state that platelet transfusions should be administered in the setting of severe GI bleed to maintain a platelet count of > 30 x 10⁹ L (or > 50 x 10⁹ L if endoscopy will be performed). 

The 2023 guidelines add a new recommendation that there is no benefit to routine platelet transfusion for patients on antiplatelet medication.

They also add a new recommendation that they strongly (!) advise AGAINST using antifibrinolytic agents such as tranexamic acid in the context of a GI bleed because it is associated with an increase in venous thromboembolic events and seizures while not showing a positive impact on e.g. mortality from LGIB, all-cause mortality or all-cause bleeding.

Another important change for the 2023 guidelines is that they are more restrictive in recommending reversal of intentional anticoagulation. They state that most patients do NOT require reversal of their anticoagulated state.

The (now outdated) 2016 guidelines: “Endoscopic hemostasis may be considered in patients with an international normalized ratio of 1.5- 2.5 prior to or concomitant with the administration of reversal agents. Reversal agents should be considered prior to endoscopy in patients with an INR > 2.5 (conditional recommendation, very low quality evidence). 

By comparison, the 2023 guideline states:

“Although most patients with LGIB who are on vitamin K antagonists are unlikely to require reversal, we suggest reversal of patients who present with a life-threatening LGIB AND (!) have an INR substantially exceeding the therapeutic range.” For such hyper-anticoagulated patients, 4-factor PCC is preferred over fresh frozen plasma.  

They furthermore state:

“For patients on direct oral anticoagulants, we suggest reversal only for the small subset of patients who present with a life-threatening LGIB that does not respond to initial resuscitation and cessation of the anticoagulant alone.” 

Patients on one of the new oral anticoagulants should receive the specific antidote to their particular medication (idarucizumab for reversing dabigatran; andexanet for reversing apixaban or rivaroxaban). 

The above patient met none of these criteria and did not require reversal of his unknown agent. The patient also did not meet criteria for packed red blood cell transfusion.

Both the 2016 and 2023 guidelines recommend a restrictive transfusion strategy to a goal hemoglobin of 7.0 g/dL (versus a liberal strategy to a hemoglobin of 9 g/dL).