Improvement of the reversible unilateral ureteral obstruction model.

The reversible unilateral ureteral obstruction (RUUO) model is pivotal for studying obstructive nephropathy (ON) but has limitations, including procedure complexity and inconsistent recanalization success. We developed a simpler, reliable, and efficient RUUO model, and utilized advanced auxiliary examination methods to assess hydronephrosis and renal function changes, providing evidence for procedural success. Male Sprague-Dawley rats were divided into control and experimental groups. Baseline data on glomerular filtration rate (GFR) and magnetic resonance imaging (MRI) were obtained from the control group. The experimental group was subdivided based on obstruction durations of 3, 7, 10, and 14 days. Unilateral ureteral obstruction models were created followed by obstruction release to establish the RUUO models. Dynamic renal scintigraphy with single-photon emission computed tomography was used to measure left kidney GFR pre-recanalization and on day 7 and 14 post-recanalization. MRI was used to evaluate hydronephrosis resolution. Key surgical modifications included complete removal of ligated ureter segments and wider ureter-bladder anastomosis, improving consistency and 93.35% recanalization success rate. MRI and Tc-DTPA dynamic renal scintigraphy indicated varying degrees of renal functional recovery. The 3-day obstruction group showed near-complete restoration within 1 week of recanalization. Conversely, extended obstruction durations significantly impaired recovery. The 14-day group demonstrated marked functional decline due to progressive renal fibrosis observed at 2 weeks post-recanalization. The optimized model offers simplified surgical techniques, enhanced recanalization success, and high reproducibility. These findings highlight the importance of early recanalization in preserving renal function, and provide a robust framework for future research on ON, including therapeutic strategies.