Introduction and Hypothesis <p>Patients with stage 3 or 4 pelvic organ prolapse (POP) may concurrently have hydronephrosis. Consequences of hydronephrosis, such as acute kidney injury and chronic kidney disease, have significant costs to patients and healthcare facilities. In this study, we evaluate the cost-effectiveness of renal ultrasound to screen for hydronephrosis in patients with stage 3 or 4 POP.</p> Methods <p>We designed a decision tree model comparing screening renal ultrasound versus usual care for patients with stage 3 or 4 POP. In the screening strategy, patients undergo ultrasound and subsequently proceed with pessary or surgery should they screen positive for hydronephrosis or proceed with expectant management, pessary, or surgery should they screen negative. In the non-screening strategy, patients choose treatment as they normally would and those with underlying hydronephrosis either continue to have hydronephrosis or have resolution of hydronephrosis. We modeled a time horizon of 5 years, with a 3% discount rate annually for future costs and quality-adjusted life-years (QALY). This was an IRB-exempt study.</p> Results <p>At a willingness to pay threshold of $150,000/QALY, renal ultrasound was cost-effective when the majority of patients who screen positive for hydronephrosis choose pessary instead of surgery. Screening renal ultrasound is cost-effective if less than 36.3% of patients with hydronephrosis choose surgery. At 5 years, screening renal ultrasound was cost-effective regardless of the prolapse treatment chosen by patients with hydronephrosis.</p> Conclusion <p>Routine renal ultrasound screening of patients with stage 3 or 4 POP is a cost-effective strategy to identify hydronephrosis and guide treatment that mitigates risk of permanent renal damage.</p>