Clinical scenario: Recurrent flank pain & Hydronephrosis | Diagnosis
A 10-year-old boy presents with recurrent episodes of severe left flank pain associated with vomiting, usually occurring after drinking large volumes of water during football matches. Between episodes, he is completely asymptomatic. Urinalysis is normal, and renal function is preserved. Ultrasonography demonstrates intermittent left hydronephrosis without ureteric dilatation.
What is the most likely diagnosis?
A. Nephrolithiasis
B. PUJ obstruction
C. Vesicoureteral reflux
D. Ureterocele
E. Posterior urethral valves
Correct answer & Explanation:
Correct answer: B. PUJ obstruction
Explanation:
This child has Dietl’s crisis, the classic presentation of intermittent PUJ obstruction.
Features include:
- Episodic severe flank pain
- Vomiting
- Triggered by increased urine flow (e.g., excessive fluid intake or diuretics)
- Hydronephrosis without ureteric dilatation
- Normal renal function between attacks
The obstruction is often caused by an aberrant lower-pole crossing vessel or an intrinsic narrowing of the pelviureteric junction.
Why the other options are incorrect:
- A. Nephrolithiasis – Usually causes hematuria and may show a calculus on imaging.
- C. Vesicoureteral reflux – Typically presents with recurrent febrile UTIs.
- D. Ureterocele – Causes distal ureteric obstruction and bladder abnormalities.
- E. Posterior urethral valves – Occur in infant boys with bladder outlet obstruction and bilateral urinary tract changes.
Key point:
Intermittent flank pain after heavy fluid intake with hydronephrosis but no hydroureter is highly suggestive of intermittent PUJ obstruction (Dietl’s crisis).
