Question:hard
What is the investigation of choice for screening renovascular hypertension with bilateral renal artery stenosis?
What is the investigation of choice for screening renovascular hypertension with bilateral renal artery stenosis?
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Captopril renogram needs a normal kidney to compare against; in bilateral stenosis, use Duplex Doppler instead.
Updated On: Jul 8, 2026
- Duplex Doppler study
- Captopril enhanced radionuclide scan
- USG
- MR angiography
Show Solution
The Correct Option is A
Solution and Explanation
Step 1: Understanding the Question:
We need the best screening test for renovascular hypertension in a patient where both renal arteries could be narrowed.
Step 2: Key Formula or Approach:
Screening tests for renal artery stenosis fall into two types: functional tests that compare the two kidneys against each other (like the captopril renogram), and direct flow measuring tests that look at each artery on its own (like Duplex Doppler). The choice between them depends on whether the disease is one sided or both sided.
Step 3: Detailed Explanation:
A captopril renogram works by showing a difference between a healthy kidney and a stenosed one after the drug is given. This side-to-side comparison breaks down when both kidneys are equally affected, since there is no normal side left to compare against. Duplex Doppler ultrasound instead measures the actual speed of blood in each renal artery directly, so it can flag narrowing on either or both sides without needing a healthy reference kidney. It is also cheap, quick, and avoids contrast or radiation, which suits it well as a first screening step. Plain ultrasound alone only shows kidney shape and size, not flow, so it misses the stenosis itself. MR angiography gives a detailed picture of the artery anatomy but is usually kept as a confirmatory test after screening flags a problem.
Step 4: Final Answer:
In bilateral renal artery stenosis, Duplex Doppler study is the screening test of choice because it does not depend on comparing one kidney to the other.
\[ \boxed{\text{Duplex Doppler study}} \]
We need the best screening test for renovascular hypertension in a patient where both renal arteries could be narrowed.
Step 2: Key Formula or Approach:
Screening tests for renal artery stenosis fall into two types: functional tests that compare the two kidneys against each other (like the captopril renogram), and direct flow measuring tests that look at each artery on its own (like Duplex Doppler). The choice between them depends on whether the disease is one sided or both sided.
Step 3: Detailed Explanation:
A captopril renogram works by showing a difference between a healthy kidney and a stenosed one after the drug is given. This side-to-side comparison breaks down when both kidneys are equally affected, since there is no normal side left to compare against. Duplex Doppler ultrasound instead measures the actual speed of blood in each renal artery directly, so it can flag narrowing on either or both sides without needing a healthy reference kidney. It is also cheap, quick, and avoids contrast or radiation, which suits it well as a first screening step. Plain ultrasound alone only shows kidney shape and size, not flow, so it misses the stenosis itself. MR angiography gives a detailed picture of the artery anatomy but is usually kept as a confirmatory test after screening flags a problem.
Step 4: Final Answer:
In bilateral renal artery stenosis, Duplex Doppler study is the screening test of choice because it does not depend on comparing one kidney to the other.
\[ \boxed{\text{Duplex Doppler study}} \]
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