Appraisal of testicular volumes: volumes matching ultrasound values referenced to stages of genital development

Abstract

BackgroundTesticular volumes obtained with orchidometers or external linear measurements in the scrotum (centimeter ruler or calipers) grossly over-estimate ultrasound volumes, have much variability and may not be accurate or reproducible. The reference of the values obtained by orchidometers or US, to age or Tanner stages is not useful to determine the normal values for stages of puberty, because overlapping of ages and values. Pubertal development is determined by two events, genital and pubic hair development, that should be analyzed independently because one could be out of step with the other. The ultrasound (US) measurement of testicular volumes is the gold standard but is somewhat inconvenient, because it requires another procedure and, mainly, is costly.The solution of the problems would be to determine testicular volumes matching US values, from the width of the testis obtained in the scrotum with a centimeter ruler, by formulas recently described, and to reference them to the stages of genital development.MethodsThe width and length of the testes in the scrotum with a centimeter ruler were obtained in 159 study subjects, in different stages of genital development and adults, for a total of 318 testicular determinations, from the age of 3 to 34 years. The width obtained in the scrotum was corrected by subtracting the values of the double scrotal skin (ss). The formulas were then applied and the testicular volumes matching US values were calculated. The volumes and the range of ages for different stages of genital development were determined. Penile measurements were obtained in 145 subjects and pubic and other hair recorded.Paired and unpaired 2 tail student t-test was used to compare the means of the different groups expressed as means and SD and, in addition the Wilcoxon rank sum test and Bootstrap methods for the testicular volume groups. A p value of 0.05 or less was considered significant.The Institutional Review Board (IRB) of Nationwide Children’s Hospital determined that this study did not require IRB approval.ResultsWith a simple measurement of the width of the testis in the scrotum, with a centimeter ruler, testicular volumes matching US values were calculated and normative values for each stage of genital development were determined.ConclusionThis information should solve present problems.Electronic supplementary materialThe online version of this article (doi:10.1186/s13633-017-0046-x) contains supplementary material, which is available to authorized users.

Anogenital distance and reproductive outcomes in 9‐ to 11‐year‐old boys: the INMA‐Granada cohort study

“…Moreover, as noted above, the association observed between AGD and testicular growth but not Tanner stage may be explained by the fact that pubic hair growth was not graded separately from genital development. It should also be taken into account that Prader's orchidometer may be less accurate than scrotal ultrasound to measure testicular volume in children (Diamond et al ., ; Sotos & Tokar, ), and the correlation of volumes with Tanner stages of genital development may not be useful due to an overlapping of these values (Sotos & Tokar, ). Thus, the partial disagreement between increased testicular volume (>3 mL) and Tanner stage >G1 may also be partly attributable to some degree of misclassification of testicular volume.…”

A medical calculator to determine testicular volumes matching ultrasound values from the width of the testis obtained in the scrotum with a centimeter ruler

“…The determination of the testicular volume is of considerable importance to assess the onset, progression and disorders of puberty, the effect of cryptorchidism and orchiopexy, abnormal testicular development, detection of Klinefelter syndrome, microorchidism or macroorchidism, and a number of other conditions; and in adults, assessment of fertility. Low testicular volume correlates with tubular size, function and spermatogenesis [ 1 ].…”

“…All the clinical methods calculate the volumes by the ellipsoid eq. Width 2 x Length x (π)/6 (W 2 x L × 0.52), grossly overestimate ultrasound (US) volumes by 70 to 80% for adults, 100 to 150% for pubertal, and 150 to 250% for prepubertal subjects, mainly because the inclusion of the scrotal skin and epididymis and may not be accurate of reproducible [ 1 ].…”

“…These formulas equivalent to the US equations were previously validated and results matching US values of different authors previously reported. (For further details on equations and formulas, see reference [ 1 ]).…”

“…Benefit : The information provided by the calculator will solve the problem of overestimation by the orchidometers and the external measurements, problems with the reference of values to age, and Tanner stages [ 1 ], would permit assessment of the beginning and progression of puberty, of micro and macroorchidism, and other conditions mentioned. Assessment of factors affecting differential testicular volumes between the left and right testis (i.e.…”