INSIGHT ON PATHOGENESIS OF VARICOCELES: RELATIONSHIP OF VARICOCELE AND BODY MASS INDEX MATTHEW E. NIELSEN, STEPHEN ZDERIC, STEPHEN J. FREEDLAND, AND JONATHAN P. JAROW ABSTRACT Objectives. Varicoceles, present in 15% to 20% of men, are the most common abnormal finding among men presenting with infertility, yet controversy exists regarding their etiology. Anecdotal experience suggests that varicoceles are more prevalent in lean men, supporting the “nutcracker” effect of the superior mesen- teric artery compressing the left renal vein over the aorta. We examined this hypothesis in a large adult population. Methods. A total of 2106 men were evaluated for infertility or erectile dysfunction from 1990 to 1996. The men were examined for the presence and severity of a varicocele. The association between age, height, body mass index, year of evaluation, and reason for consultation and the presence and severity of a varicocele was examined using logistic regression analysis. Results. The mean age was 47 years (range 18 to 85), and the median body mass index was 26.4 kg/m 2 (range 15.4 to 53.3). A varicocele was present in 398 men (18.9%). Stratified by grade, 59 (14.8%) were grade III, 155 (38.9%) were grade II, and 184 (46.2%) were grade I. The prevalence of varicoceles in the erectile dysfunction group (12.7%) was significantly less (P 0.001) than in the infertile group (32.2%). Multivariate logistic regression analysis revealed a statistically significant inverse relationship between body mass index and the presence of a varicocele. Conclusions. Varicoceles were less likely to be diagnosed among obese men. Although this suggests that the “nutcracker” phenomenon or other biophysical effects of increased adiposity may play a role in the pathogenesis, other factors could not be excluded as contributing to our findings. UROLOGY 68: 392–396, 2006. © 2006 Elsevier Inc. V aricocele, a dilation of the veins of the pam- piniform plexus in the scrotum, is a common entity in urologic practice. Population-based stud- ies, largely school and military screening physical examinations, have led to estimates of varicocele prevalence in the general population of 15% to 20%. 1–3 Conversely, the prevalence of varicocele among men attending an infertility clinic ranges from 30% to 40%, making it the most common abnormal physical examination finding in pa- tients presenting for evaluation of male factor infertility. 4–6 The pathogenesis of varix formation, although somewhat unclear, is thought to be related to var- ious factors resulting in an increased pressure in the veins of the pampiniform plexus and its venous drainage. Classically, these include absent or in- competent venous valves in the internal spermatic veins, persistent embryologic venous collaterals, and increased venous pressure in the left renal vein. 7 The observation of an approximate 75% to 90% left-sided predominance suggests that the an- atomic relationships of the left internal spermatic vein at its insertion into the left renal vein are of particular relevance, including possible compres- sion of the left renal vein between the aorta and superior mesenteric artery, colloquially referred to as the “nutcracker phenomenon.” 8 Anecdotal experience has led to the suggestion that varicocele may be more common in tall, lean men, although a study of body composition in ad- olescents with varicocele found no significant rela- This study was supported by the American Foundation for Uro- logical Disease/American Urological Association Education and Research Scholarship Award. From the Department of Urology, Johns Hopkins Hospital, Bal- timore, Maryland; and Children’s Hospital of Philadelphia, Phil- adelphia, Pennsylvania Reprint requests: Matthew E. Nielsen, M.D., James Buchanan Brady Urological Institute, Johns Hopkins School of Medicine, 600 North Wolfe Street, Baltimore, MD 21287-2101. E-mail: nielsen@jhmi.edu Submitted: August 5, 2005, accepted (with revisions): Febru- ary 1, 2006 ADULT UROLOGY © 2006 ELSEVIER INC. 0090-4295/06/$32.00 392 ALL RIGHTS RESERVED doi:10.1016/j.urology.2006.02.005