Kidney and Ureteral Calculi in a 5-Month-Old Infant: A Case of Ultra-Mini Percutaneous Nephrolithotomy

Aim: Urolithiasis is rare in infancy, yet its incidence has been increasing in recent years, partly due to the widespread use of ultrasonography. Pediatric stone disease is characterized by higher recurrence rates than in adults, necessitating minimally invasive treatment approaches that minimize morbidity and preserve long-term renal function. Case Presentation: We report the case of a 5-month-old male infant who presented with restlessness, fever, and anorexia, with a recent history of recurrent urinary tract infections. Imaging revealed left renal and right ureteral calculi. Right ureteral stones were treated via ureterorenoscopy (4.5 Fr ultra-thin ureteroscope) and Holmium:YAG laser lithotripsy with subsequent double-J stent placement. Renal stones, including a 1 cm lower calyceal and a 2 cm middle calyceal calculus, were managed using Ultra-Mini Percutaneous Nephrolithotomy (UmPNL) with a 9.5 Fr nephroscope, resulting in complete stone clearance. The total operative time was 90 minutes with a fluoroscopy duration of 32 seconds. No intra-operative or post-operative complications, bleeding, or fever were observed. The nephrostomy catheter was removed on post-operative day 1, the Foley catheter on day 2, and the patient was discharged uneventfully. Both ureteral stents were removed four weeks later under sedation. Discussion: Pediatric stone disease in infants is associated with multifactorial etiologies including anatomical, metabolic, and infectious factors. Technical challenges are amplified in this population due to the small collecting system, fragile renal cortex, and narrow ureteral dimensions. Advances in miniaturized endoscopic instruments and the use of Holmium:YAG laser have significantly improved the safety and efficacy of ureteroscopic and percutaneous approaches in children. Compared with extracorporeal shock wave lithotripsy, percutaneous techniques offer higher single-session stone-free rates and eliminate the need for repeated anesthesia. Literature reports confirm the feasibility of percutaneous nephrolithotomy in infants when performed in experienced centers with appropriate equipment. Conclusion: This case demonstrates that combined ureterorenoscopy and ultra-mini percutaneous nephrolithotomy can be safely and effectively performed in infants as young as 5 months, achieving complete stone clearance without complications. In high-volume centers with surgical expertise, such minimally invasive approaches represent a reliable and practical option for the management of infantile urolithiasis.