Factors associated with treatment decisions in pregnant women with symptomatic hydronephrosis presenting to the emergency department: a retrospective cohort study

OBJECTIVE: We aimed to identify the factors associated with the clinician's decision between conservative and invasive treatment for pregnant women with symptomatic hydronephrosis who presented to the emergency department. METHODS: A total of 102 pregnant patients presenting to the emergency department between 2022 and 2025 with symptoms of urinary tract infection or obstruction and diagnosed with hydronephrosis by renal ultrasonography were included in the study. Demographic and obstetric characteristics, hydronephrosis grades, laboratory findings, and treatment approaches were recorded. Statistical analyses included nonparametric tests, categorical comparisons, correlation analysis, logistic regression, Firth's penalized logistic regression, and ROC curve analysis. Multiple comparisons were adjusted using the Benjamini-Hochberg FDR method, and the model was internally validated by bootstrap resampling. RESULTS: Grade 2 hydronephrosis was detected in 46.1% of patients, Grade 3 in 50.0%, and Grade 4 in 3.9%. Conservative treatment was administered to 68.6% of the patients, while 31.4% underwent invasive treatment. Hydronephrosis grade was the most significant factor associated with the treatment decision (AUC: 0.856), with Grade ≥ 3 as the optimal cutoff value. Gestational week showed a negative correlation with hydronephrosis grade. A significant difference was found in leukocyte counts across different grades of hydronephrosis, and a moderate-to-strong positive correlation was detected between leukocyte count and the neutrophil/lymphocyte ratio. In the Firth penalized multivariable logistic regression model, higher hydronephrosis grade (OR: 121.27) and younger age (OR: 0.84) were independently associated with the decision for invasive treatment. CONCLUSION: The grade of hydronephrosis is the dominant factor associated with the clinical decision for invasive intervention in pregnant patients with symptomatic hydronephrosis. While other clinical markers may appear predictive, they largely act as proxies for hydronephrosis severity. Prospective studies with standardized treatment protocols and comprehensive outcome assessment are warranted.