Differential Diagnosis

The patient's presentation of sudden sharp abdominal and low back pain, along with a pulsatile mass on abdominal examination, suggests a vascular origin. Here's a categorized differential diagnosis:

• Single most likely diagnosis

  • Abdominal aortic aneurysm (B): The presence of a pulsatile abdominal mass, severe pain, and a history of hypertension and significant tobacco use strongly supports this diagnosis. The patient's age and risk factors also align with the typical demographic for abdominal aortic aneurysms.

• Other Likely diagnoses

  • Myocardial infarction (A): Although the primary complaint is abdominal and back pain, myocardial infarctions can sometimes present with atypical pain patterns, especially in older adults. The patient's history of hypertension and tobacco use also increases the risk for coronary artery disease.
  • Mesenteric ischemia (D): This condition involves insufficient blood flow to the intestines and can cause severe abdominal pain. The patient's history of tobacco use and hypertension are risk factors, but the presence of a pulsatile mass is more suggestive of an aneurysm.

• Do Not Miss diagnoses

  • Aortic dissection: While not listed among the options, aortic dissection is a critical diagnosis that must be considered in any patient presenting with severe, sudden-onset back or abdominal pain, especially with a history of hypertension. It can be deadly if missed.
  • Ruptured abdominal aortic aneurysm: This is a subset of abdominal aortic aneurysm but is critical to identify immediately due to its high mortality rate if not promptly treated.

• Rare diagnoses

  • Diverticulitis (C): Although diverticulitis can cause severe abdominal pain, it typically presents with fever, changes in bowel habits, and tenderness in the lower left abdomen, which does not fully align with this patient's presentation. The presence of a pulsatile mass and the pattern of pain make this diagnosis less likely.
  • Other vascular or non-vascular causes: There are numerous other rare conditions that could potentially cause the patient's symptoms, including other types of aneurysms, arterial thrombosis, or even non-vascular causes like pancreatitis or musculoskeletal issues. However, these are less likely given the specific findings and risk factors presented.