This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Surgery
[{'content': 'DTPA scan of hypertensive young lady is normal, USG shows small kidney on left side. Next investigation will be - \nSelect and explain. \nA. CT Scan abdomen, B. Retrograde pyelogram, C. Digital subtraction angiography, D. DMSA', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Hypertension in a young female is most probably due to renal artery stenosis (cause fibromuscular dysplasia)\nDTPA scan which shows the GFR comes to be normal because of increased renin activity.\nDigital subtraction angiography or Doppler U/S will show the stenosis.\nNow MRA (Magnetic resonance angiography) has replaced all previous modalities as the most sensitive (>95%) and specific test (95%) for the diagnosis of renal artery stenosis.\nBut the most definitive diagnostic procedure is bilateral arteriography with repeated bilateral renal vein and systemic rennin determinations.', 'role': 'assistant'}]