Differential Diagnosis for High INR and Rectal Bleeding

The patient's presentation of a high International Normalized Ratio (INR) and rectal bleeding suggests a complex interplay of coagulopathy and gastrointestinal pathology. The differential diagnoses can be categorized as follows:

• Single Most Likely Diagnosis

  • Warfarin overdose or supratherapeutic anticoagulation: This is the most likely diagnosis given the high INR, which is a direct indicator of the anticoagulant effect of warfarin. Rectal bleeding in this context could be due to the anticoagulated state, making even minor bleeding sites significant.

• Other Likely Diagnoses

  • Gastrointestinal malignancy: Although less directly linked to a high INR, gastrointestinal cancers can cause rectal bleeding. If the patient is on anticoagulation therapy for another condition (e.g., atrial fibrillation), the high INR could be coincidental.
  • Diverticulitis or diverticulosis: These conditions can cause rectal bleeding and might be more common in the elderly population, who are also more likely to be on anticoagulants.
  • Peptic ulcer disease: While more commonly associated with upper GI bleeding, peptic ulcers can occasionally cause lower GI symptoms, including rectal bleeding, especially if the patient has a high INR.

• Do Not Miss Diagnoses

  • Upper GI bleed with rapid transit: Although the patient presents with rectal bleeding, an upper GI source (e.g., esophageal varices, ulcers) with rapid transit could mimic lower GI bleeding. Missing this diagnosis could be fatal due to the potential for significant blood loss.
  • Ischemic bowel disease: This condition could cause rectal bleeding and might be exacerbated or complicated by anticoagulation. It requires prompt diagnosis and treatment to prevent severe outcomes.
  • Infectious colitis: Certain infections (e.g., Clostridioides difficile) can cause significant lower GI symptoms, including bleeding. The presence of a high INR could complicate the clinical picture and management.

• Rare Diagnoses

  • Hemorrhagic telangiectasia (Osler-Weber-Rendu syndrome): A rare genetic disorder that leads to the formation of abnormal blood vessels, which can cause bleeding, including rectal bleeding.
  • Amyloidosis: A condition characterized by the deposition of amyloid proteins in various tissues, which can lead to bleeding due to vascular fragility or gastrointestinal involvement.
  • Vasculitis: Certain types of vasculitis can affect the gastrointestinal tract and cause bleeding, although this would be a rare cause of rectal bleeding in the context of a high INR.

Workup in the Emergency Department

• Immediate Steps:
  • Stabilize the patient with fluid resuscitation and blood transfusions as needed.
  • Administer vitamin K and consider fresh frozen plasma (FFP) or prothrombin complex concentrate (PCC) to reverse anticoagulation if due to warfarin.
• Diagnostic Tests:
  • Complete blood count (CBC) to assess for anemia and thrombocytopenia.
  • Coagulation studies (PT/INR, aPTT) to evaluate the extent of anticoagulation.
  • Type and screen for potential blood transfusion.
  • Electrolyte panel and renal function tests to assess for any electrolyte imbalances or renal dysfunction that could contribute to bleeding.
  • Imaging studies (e.g., CT abdomen/pelvis) to evaluate for a source of bleeding, especially if the patient is stable enough for the study.
  • Endoscopy (upper and/or lower) to directly visualize the gastrointestinal tract for sources of bleeding.
• Consultations:
  • Gastroenterology for assistance with endoscopy and management of gastrointestinal causes.
  • Hematology for guidance on anticoagulation reversal and management of coagulopathy.