An antegrade nephrostogram is a diagnostic medical procedure used to evaluate the upper urinary tract, particularly the kidneys and ureters. It involves the insertion of a thin, flexible tube called a nephrostomy catheter through the skin and into the renal pelvis of the kidney, typically guided by imaging techniques such as fluoroscopy or ultrasound. Once in place, a contrast dye is injected through the catheter, allowing for real-time visualization of the upper urinary system as the dye travels through the ureters and into the bladder. This procedure helps doctors identify blockages, strictures, or other abnormalities in the urinary tract, assisting in the diagnosis and planning of appropriate treatment for the patient.