Diagnostic value of ultrasound in different positions for detecting nutcracker syndrome during physical examination...

To examine the ultrasonographic parameters and diagnostic efficacy of nutcracker syndrome (NCS) in two positions and thus to ensure accurate recruitment.

According to the presence or absence of left varicocele, 184 teenagers from Air Force medical selection in 2024 were classified into the NCS-positive group or the control. Receiver operating characteristic (ROC) curve analysis was used to evaluate the diagnostic performance of ultrasound parameters in the seated anteversion and supine position. Independent predictors were determined via regression analysis. Individual and combined diagnostic prediction models were developed based on these independent predictors through nomogram and the calibration curve.

ROC curve analysis showed the superior diagnostic efficacy for NCS in the seated anteversion position. Regression analysis identified two independent diagnostic predictors: the diameter ratio between the dilatation and stenosis of the left renal vein (D2/D1) and the peak velocity (V1) at the stenosis.And the combination of these two diagnostic parameters (the cutoff value of D2/D1: 2.38 and the cutoff value of V1: 69.5 cm/s) achieved an AUC of 0.821 with a sensitivity of 68.3 % and a specificity of 84.3 %. The calibration curve demonstrated good consistency between the predictions made by the nomogram and actual clinical observations.

This study established the diagnostic criteria at the seated anteversion position for NCS, indicating that D2/D1 and V1 of left renal vein serve as independent diagnostic parameters. In the future, these criteria can enhance accuracy in aviation recruitment medical examinations.