Summary: A 34-year-old female, without comorbidities, presented to the emergency department with sudden right flank pain. Initial workup showed elevated WBC (14.5) and normal creatinine (0.81), but later developed fever spikes and rising CRP (59.50). Gentamicin treatment was initiated. Transferred for a Diuretic Renogram, confirming suboptimal function of the right kidney with obstruction at the renal pelvis/PUJ. Split functions indicated 32% for the right kidney and 68% for the left. Radiological workup included ultrasound, CT KUB with contrast, and CT Urography, revealing right renal acute hydronephrosis without evidence of stones. Management involved symptomatic treatment, but with persistent symptoms, Gentamicin prophylaxis was initiated. The patient was transferred for Renogram, detecting suboptimal right kidney function. A planned stent insertion followed by Robotic-assisted and laparoscopic pyeloplasty was scheduled. Discussion: Uretero Pelvic Junction Obstruction (UPJO) is a partial blockage where the ureter enters the kidney. Congenital UPJO can result from intrinsic narrowing, high ureter insertion, ureteral polyps, or accessory renal artery crossing vessels causing extrinsic compression. Most cases are detected on prenatal ultrasound, while postnatal presentations include UTI, abdominal mass, hematuria, and intermittent flank pain. Diagnosis involves CT urography and diuretic renogram, confirming suboptimal function (<40%) in our case. Conclusion: Diagnosing this case proved challenging, initially resembling kidney stones. CT urography and diuretic Renogram confirmed suboptimal kidney function (32% right, 68% left). Surgical intervention is recommended if function falls below 40%, as prolonged UPJO may lead to severe complications. The patient underwent Robotic-assisted and laparoscopic pyeloplasty, emphasizing the importance of timely intervention in managing UPJO cases.

Keywords: Congenital ureteropelvic junction obstruction in adult.