Percutaneous Nephrolithotomy (PNL) was accepted as a treatment modality for large renal stones since 1980. Although radiation exposure during PNL is within the safe limits for expert endourologist, the mutagenic hazard is still present especially in pediatric population. Therefore, employing an alternative imaging technique during PNL would be of added advantage. So, the investigators want to compare the efficacy of ultrasound guided PNL with the conventional (fluoroscopy guided) PNL in pediatric population. If ultrasound guided PNL was as effective as conventional one, this means that many children could be protected from the variable hazards of radiation exposure.

The incidence of pediatric urolithiasis varies by geographic area. Most cases of pediatric urolithiasis are associated with anatomic or metabolic abnormalities or urinary tract infection . PNL can be performed safely and effectively in children by experienced surgeons, resulting in a high stone-free rate and lower requirement for ancillary treatment. In adults, PNL is performed under fluoroscopic or ultrasound guidance. In pediatric age group, fluoroscopic guidance was preferred in most of the reported studies. However, fluoroscopy exposes the patient to radiation. The International Commission on Radiological Protection recommends that whole body exposure in adults should be limited to an effective dose of 20 mSv per year over 5 years. In young children, it is particularly important to protect the developing gonads and thyroid gland, as the long-term effects of exposing these organs to radiation are still unclear. In contrast to fluoroscopic guidance, ultrasound guidance does not expose the patient to radiation, it also can provide real-time monitoring during the puncturing procedure. The path and depth of the needle, and the anatomy in and around the kidney, are clearly visible on ultrasound examination

Inclusion Criteria:

• All kidney stones in pediatric age group and indicated for PNL.

Exclusion Criteria:

• Children unfit for the procedure or non indicated for it.
• Parental refusal.