Differential Diagnosis

The patient's presentation is complex, with multiple potential causes for her symptoms. Here's a categorized differential diagnosis:

• Single most likely diagnosis
  • Retroperitoneal hemorrhage: The patient is on warfarin, which increases the risk of bleeding. The severe low back pain, hypotension, and elevated INR support this diagnosis. The patient's hematocrit is low, indicating significant blood loss.
• Other Likely diagnoses
  • Pancreatitis: The patient's elevated amylase and lipase levels suggest pancreatitis. However, the absence of abdominal pain initially and the presence of severe low back pain make this diagnosis less likely.
  • Bowel infarction: The patient's abdominal pain, elevated BUN and creatinine, and low blood pressure could suggest bowel infarction. However, the lack of abdominal tenderness and the presence of severe low back pain make this diagnosis less likely.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
  • Perforated peptic ulcer: Although the patient's stool is negative for occult blood, a perforated peptic ulcer could still be present. The patient's abdominal pain, low blood pressure, and elevated BUN and creatinine make this diagnosis possible.
  • Sepsis: The patient's low blood pressure, elevated BUN and creatinine, and minimal responsiveness to deep stimuli could suggest sepsis. Although the patient's urinalysis does not show evidence of a urinary tract infection, sepsis from another source is still possible.
• Rare diagnoses
  • Aortic dissection: The patient's severe low back pain and hypotension could suggest an aortic dissection. However, this diagnosis is less likely given the patient's age and the absence of other symptoms such as chest pain or unequal blood pressures in the arms.
  • Spinal epidural hematoma: The patient's severe low back pain and minimal responsiveness to deep stimuli could suggest a spinal epidural hematoma. However, this diagnosis is rare and would require further imaging to confirm.