Effect of Oxybutynin on Opioid Use After Urologic Surgery in Children

The goal of this clinical trial is to determine whether giving oxybutynin before urologic reconstruction surgery reduces the amount of opioid pain medication needed in children. Oxybutynin is a medication that helps reduce bladder spasms, which can cause pain and discomfort after surgery. The main question this study aims to answer is: Does giving oxybutynin before surgery reduce the amount of opioid pain medication children need during the first 6 hours after surgery? Researchers will compare oxybutynin with a placebo (a tablet containing no active medication) to see whether oxybutynin reduces opioid use after surgery.

Inclusion Criteria: * All children aged 0 to 17 years old admitted for pyeloplasty or hypospadias repair. There is no minimum weight for inclusion Exclusion Criteria: * Contraindications to anticholinergic medications * Urinary retention disorders * Gastrointestinal obstruction/ileus * Contraindications to anesthetic protocol, including 1) allergy to any anesthetic medication in protocol, 2) refusal of regional technique, 3) contraindications to ketorolac (i.e., recent GI bleed, recent intracranial bleed, renal dysfunction, acute kidney injury)