Introduction: Percutaneous nephrolithotomy (PCNL) is considered as the “gold standard” treatment for large (>2 cm) and complex kidney stones. We present a case of transient tone loss of the anterolateral abdominal wall, which is a rare complication after PCNL.

Case Report: A 50-year-old male with a complete staghorn stone of the right kidney underwent standard PCNL in prone position at the 11th intercostal space. On the 6th post-operative day the patient complained on painless bulge in the right flank. Computed tomography (CT) scan in supine position revealed no signs of herniation, retroperitoneal hematoma, or residual fragments. Flank bulge was attributed to the muscle tone loss either because of the 11th intercostal nerve injury by the needle or nerve compression by the Amplatz sheath. Within next six months flank bulge has completely resolved.

Conclusion: Flank bulge after PCNL although rare but possible and transient condition. Nerve injury seems to be the most likely cause.