Acute Pyelonephritis MCQ — NEET PG Practice Question | NEETPGAI
Acute Pyelonephritis
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stethoscope Medicine
A 28-year-old woman presents with 2 days of high-grade fever with rigors, severe right flank pain with costovertebral angle tenderness, dysuria, and vomiting. Urinalysis shows marked pyuria, WBC casts, positive nitrites, and bacteriuria. Renal ultrasound with color Doppler reveals mild global kidney enlargement with preserved corticomedullary differentiation. The structure marked **A** (wedge-shaped hypoperfused area in the upper pole) is identified on color Doppler imaging. What is the most likely diagnosis and what does this finding represent?
A. Acute pyelonephritis with focal area of reduced perfusion due to ascending infection and localized inflammation
B. Acute pyelonephritis with focal renal infarction due to septic emboli from hematogenous spread
C. Renal abscess with complete loss of perfusion requiring immediate percutaneous drainage
D. Acute glomerulonephritis with immune complex deposition causing segmental hypoperfusion
Explanation
Why option 1 is correct
The wedge-shaped hypoperfused area on color Doppler in the setting of acute pyelonephritis with ascending infection from the bladder represents focal renal inflammation and reduced perfusion characteristic of acute pyelonephritis. This patient has the classic triad of fever, flank pain, and costovertebral angle tenderness with pyuria, WBC casts, positive nitrites, and bacteriuria—all hallmarks of acute pyelonephritis. The wedge-shaped pattern on ultrasound with color Doppler reflects localized inflammation and edema in the renal parenchyma, typically in the distribution of a renal lobe, resulting in decreased perfusion. According to IDSA Guidelines and Harrison's Internal Medicine, acute pyelonephritis most commonly results from ascending infection (70–80% uropathogenic E. coli), and imaging findings such as wedge-shaped hypoperfusion on color Doppler are typical of focal pyelonephritis without abscess formation or obstruction.
Why each distractor is wrong
Option 0 (Renal infarction from hematogenous septic emboli): While hematogenous spread can occur in acute pyelonephritis (particularly with S. aureus or Candida in immunocompromised patients), it is uncommon and accounts for a minority of cases. The clinical presentation and urinalysis findings (pyuria, WBC casts, nitrites, bacteriuria) are far more consistent with ascending infection from the bladder. Renal infarction would typically present as a wedge-shaped area of non-perfusion on imaging but is not the primary mechanism in this case of ascending acute pyelonephritis.
Option 2 (Renal abscess requiring immediate drainage): A renal abscess would show a fluid collection with rim enhancement and would typically present with persistent fever despite antibiotics or clinical deterioration. This patient has uncomplicated acute pyelonephritis with preserved corticomedullary differentiation and no evidence of a discrete fluid collection. Abscess formation is a complication that develops in a minority of cases, not the typical presentation.
Option 3 (Acute glomerulonephritis with immune complex deposition): Acute glomerulonephritis presents with hematuria, proteinuria, hypertension, and edema—not with the acute bacterial infection markers (nitrites, bacteriuria, WBC casts) seen here. The clinical and laboratory picture is diagnostic of bacterial infection, not immune-mediated glomerular disease. Segmental hypoperfusion is not a feature of acute glomerulonephritis.
High-YieldNEET PG
Wedge-shaped hypoperfusion on renal ultrasound color Doppler in acute pyelonephritis reflects focal renal inflammation from ascending infection and is a typical imaging finding in uncomplicated acute pyelonephritis—not abscess, not infarction.
IDSA Guidelines for Acute Pyelonephritis 2010; Harrison's Internal Medicine
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