A 3-week-old male infant presents with poor feeding, irritability, and fever of 38.5°C. Urine dipstick shows leucocytes 3+ and nitrites positive. The urine culture grows >10^5 CFU/mL E. coli. After antibiotic treatment, DMSA renal scintigraphy at 4–6 months shows a cortical scar in the left kidney. What is the MOST important investigation to be done acutely and why?
- A Repeat DMSA to assess scar progression
- B Renal biopsy to assess interstitial nephritis
- C Voiding cystourethrogram (VCUG) to exclude vesicoureteral reflux ✓
- D Intravenous urogram to assess kidney size
Correct answer: C. Voiding cystourethrogram (VCUG) to exclude vesicoureteral reflux
Explanation
Voiding cystourethrogram (VCUG) is essential after a first UTI in a child younger than 2 years and in all male infants with UTI, because the risk of vesicoureteral reflux (VUR) is highest in this age group. VUR allows infected urine to reach the upper urinary tract, causing pyelonephritis and ultimately renal scarring (reflux nephropathy). Identifying VUR guides decisions about antibiotic prophylaxis and need for surgical correction. DMSA scintigraphy is performed at 4–6 months post-infection to identify permanent renal scars, not during acute illness.
Reference: Ghai Essential Pediatrics, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.