Infertility & Sexual Dysfunction(구연) (E-188) 총 운동성 정자 수 예측을 위한 정계정맥류 수술 후 정액검사 예측 노모그램의 외부 검증: 다기관 연구 연세의대 세브란스병원 비뇨의학교실¹, 순천향대학교 천안병원 비뇨의학교실², 마리아병원 비뇨의학과³, CHA의과학대학교 서울역센터 비뇨의학교실⁴ 장원식¹, 김기홍², 임경택³, 이종수¹, 허지은¹, 김대근⁴ Objectives: To externally validate the Samplaski’s post-varicocele repair semen analysis nomogram to confirm the predictive accuracy of total motile sperm count (TMC). Materials and Methods: A total of 300 patients who underwent varicocelectomy between July 2016 and July 2019 from 4 multicenters were included in the validation cohort. The validated TMC prediction nomogram included left varicocele grade and semen volume, concentration, and motility. Pearson correlation coefficient and calibration plots were used to determine the predictive accuracy of the nomogram for post-varicocele repair TMC. Locally-weighted scatter-plot smoothing line was used and the calibration plot was assessed. The calibration plot was verified by R-squared which measures of nearness of data to the fitted regression line by linear regression model. Results: There were three surgical techniques used for varicocelectomy among the cases (laparoscopic, 20 cases; inguinal approach, 30 cases; microscopic subinguinal approach, 250 cases). The predictive performance of the externally validated TMC nomogram was revealed by Pearson correlation coefficient (R=0.328; 95% confidence interval (CI) 0.220−0.435; p<0.001). Compared to Samplaski’s nomogram result (R=0.581; CI 0.186−0.729), our study also revealed a statistically significant rate. However, it had a relatively lower correlation coefficient rate and the predicted TMC was lower than the observed post-varicocelectomy TMC. The calibration plot for TMC revealed that the agreement between the predicted TMC and observed TMC was plausible. However, it had low explanatory power in this nomogram model. Conclusion: This external validation of the post-varicocele repair Samplaski’s nomogram reveals its lower correlation coefficient rate to predict post-varicocelectomy TMC. The nomogram demonstrated that the predicted TMC showed a relatively lower count than the observed post-varicocelectomy TMC by externally validated cohort. keywords : Spermatozoa, Varicocele, Nomograms