Urgent considerations

See Differentials for more details

Severe lower gastrointestinal (GI) bleeding

Initial evaluation of the patient includes assessment of the severity of the GI bleeding and of the risk to the patient. High-risk patients presenting with severe lower GI bleeding need to be identified and aggressively resuscitated. High-risk patients include those with:

  • Hemodynamic instability

  • Serious comorbid states

  • Persistent bleeding

  • A requirement for multiple blood transfusions.

Severe lower GI bleeding has been defined as continued bleeding within the first 24 hours of hospitalization (transfusion of ≥2 units of blood and/or hematocrit decrease of ≥20%).[24][25][26] Acute on chronic bleeding may also present with hemodynamic instability. Resuscitation is required along with diagnostic evaluation and management. 

The following clinical features have been found to be associated with severe bleeding:[24][25][27]

  • Systolic BP <115 mmHg

  • Heart rate >100 bpm

  • Syncope

  • Nontender abdomen

  • Bleeding per rectum during the first 4 hours of presentation

  • Aspirin use

  • More than 2 active comorbid states

  • Shock index ≥1. The shock index is calculated by dividing the patient’s heart rate by the systolic blood pressure and is a marker of hemodynamic instability.

Resuscitation with intravenous fluids and blood transfusions, and correction of any underlying coagulopathy or thrombocytopenia is required.[28] Coagulopathy or thrombocytopenia is corrected with either fresh frozen plasma or platelets respectively. Two large-bore peripheral intravenous catheters or a central venous line are necessary. Blood transfusion need is determined by the patient's age, rate of bleeding, and the presence of comorbid states (e.g., coronary artery disease, cirrhosis, or chronic obstructive lung disease). The presence of orthostatic hypotension, a drop in hematocrit >6%, or continuous active bleeding warrants admission to an intensive care unit for close observation.

The American College of Gastroenterology (AGA) guidelines suggest against giving fresh frozen plasma or vitamin K for patients on warfarin who present with acute GI bleeding (very low certainty evidence).[29] The AGA was unable to make a definitive recommendation regarding the use of prothrombin complex concentrate (PCC) in patients on warfarin with a GI bleed, but noted that administration of PCC may be considered for selected patients: those with a life-threatening bleed, those with a supratherapeutic international normalized ratio considerably in excess of the therapeutic range, or those for whom a massive blood transfusion is undesirable.[29] For patients on direct oral anticoagulants, the AGA guidelines suggest against PCC administration (very low certainty of evidence).[29] Dabigatran reversal with idarucizumab, and rivaroxaban or apixaban reversal with andexanet alfa, are not recommended (very low certainty evidence).[29] 

UK guidelines recommend that anticoagulant drugs should be withheld.[27]

The AGA, and others, recommend colonoscopy as one of the the initial diagnostic procedures.[3]​​[27][30]​​​​ Colonoscopy can be therapeutic as well as diagnostic, using argon plasma coagulation, epinephrine injections, and clips. Early colonoscopy (performed within 24 hours) may potentially improve diagnostic yield in acute lower GI bleeding, but evidence from randomized controlled trials indicates that it does not improve clinical outcomes in these patients.[3][31][32][33][34][35][36] Early colonoscopy may reduce the length of hospital stay.[6][35][37]

Computed tomography (CT) angiography can be used to identify the site of blood loss prior to colonoscopy.[38]​ Transcatheter angiography and intervention may be more appropriate in an unstable patient.[30][38]​

The conditions causing lower GI bleed that are more likely to present with severe bleeding include the following:

  • Angiodysplasia

  • Colonic diverticular disease

  • Dieulafoy lesion

  • Aortoenteric fistula

  • Upper GI bleeding (rapid transport)

  • Postpolypectomy.

Ischemic colitis

Ischemic colitis presents with acute colicky abdominal pain, diarrhea, and hematochezia (bright red rectal bleeding). Exam reveals lower abdominal tenderness. An abdominal CT scan is the initial test to perform if ischemic colitis is suspected. Colonoscopy is usually performed subsequently to confirm the diagnosis. Urgent management is required because of the risk of perforation. Peritoneal signs and absent bowel sounds suggest perforation or transmural infarction, necessitating urgent laparotomy.

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