Significance of testicular size measurement in andrology. I. A new orchiometer and its clinical application

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1 FERTILITY AND STERILITY Copyright ~ 1983 The American Fertility Society Printed in U.SA. Significance of testicular size measurement in andrology. I. A new orchiometer and its clinical application Hiroshi Takihara, M.D.* Jisaburo Sakatoku, M.D.* Mitsumasa Fujii, M.D.* Takahito Nasu, M.D. * M. James Cosentino, Ph.D.t Abraham T. K. Cockett, M.D.t:f: The University of Rochester School of Medicine and Dentistry, Rochester, New York, and Yamaguchi University School of Medicine, Ube, Yamaguchi, Japan When performing a physical examination in the andrology clinic, accurate measurement of testicular size is important. Two methods for measuring testicular size have been developed using calipers for measurement and comparison with plastic testicular models. We have developed a new orchiometer, which consists of a graded series of punched-out elliptical rings with the volume of the ellipsoids indicated on each ring. Testicular sizes measured by our orchiometer had a better correlation with real testicular size determined by water displacement of testes after castration when compared with those data obtained by using calipers. By the use of this orchiometer, the normal range of the adult testicular size was> 14 ml in Japan and> 17 ml in the United States. This orchiometer is valuable for the rapid and accurate assessment of sexual maturation in children and men. Fertil Steril 39:836, 1983 Testicular size is an important criterion of male reproductive function and correlates well with semen quality and fertility. Since seminiferous tubules and germinal elements account for approximately 98% of testicular mass, a reduction in the number of germ cells leads to testicular hypoplasia. 1 Two methods have been employed for measurement of testicular size. One is the measurement of testicular length and width by calipers, and another is a comparative palpation using a readymade testicular volumetric model. Both techniques have advantages; however, there are con- siderable variations in the results according to each investigator and his method (Table 1). Measurements by calipers are laborious even with proper positioning of the testis, and comparative palpations using plastic models are not necessarily accurate or precise. This is one of the reasons why testicular size measurements are apt to be downgraded in andrology clinics. The purpose of this study was to establish the accuracy of a new orchiometer, taking advantage of both previous methods, and to set a normal adult range of testicular size with this orchiometer. Received December 15, 1982; revised and accepted January 28,1983. *Department of Urology, Yamaguchi University School of Medicine. 836 Takihara et al. Testicular size, orchiometer tdepartment of Urology, The University of Rochester School of Medicine and Dentistry. *Reprint requests: A. T. K. Cockett, M.D., Department of Urology, Box 656, University of Rochester Medical Center, 601 Elmwood Avenue, Rochester, New York

2 I t } Table 1. Testicular Sizes of Adults Reported by Various Authors Author Sherins and Howards (1978)1 Prader (1966)2 Rundle and Sylvester (1962)3 Barr et al.a (1960) From Hansen and With (1952)5 Lambert (1951)6 From Hansena (1949) Mitz a (1914) Schultzea (1913) Spangaraa (1902) Mean ml afrom Rundle and Sylvester (1962).3 MATERIALS AND METHODS A NEW ORCHIOMETER Range We devised a graded series of punched-out elliptical rings with the number on each indicating the volume of the ellipsoid (Fig. 1). The proper ring was placed over the stretched scrotal skin away from the epididymis up to the midportion of the testis, and the volume was read from the oval ring with the best fit (Fig. 2). This measurement was made during the initial examination. The shape, width, and depth of the testis are postulated to be equal in configuration, and width is also postulated to be two thirds of the length. This new orchiometer comprises 15 models with a volume of 1 to 30 ml (Table 2). NORMAL TESTICULAR SIZE Testicular size was determined in 92 normal male subjects (from newborn to 80 years of age) at the andrology clinics of Yamaguchi Medical School and in 70 normal male subjects in the United States. Sperm count was> 40 million/ml in all of the United States volunteers. ORCHIOMETER ACCURACY RESULTS To confirm the accuracy of this orchiometer, the real testicular volumes, estimated by water displacement after orchiectomy for treatment of prostatic carcinoma, were compared with the measurements by this new orchiometer (26 testes) and those by calipers (38 testes). The correlation coefficient between real testicular size determined by water displacement and the size determined using calipers before surgery was In contrast, the correlation coefficient of the real testis volume and that determined with the new orchiometer was 0.81 (Fig. 3). Again the measurements were determined before surgery. NORMAL TESTICULAR SIZE From the newborn years to puberty-13 or 14 years-there is very little increase in testicular size, and a size of 5 ml or less may be considered juvenile. However, after 13 or 14 years, there is a rapid increase in testicular size; at 17 or 18 years of age, the adult form is achieved (Fig. 4). The normal adult testicular size was found to be ± 1.91 ml in Japan. If the mean ± 2 standard deviations (SD) is taken to define the normal range, we find that range to be 13.8 to 21.4 ml. The normal adult testicular size investigated at Rochester, New York, was 24.8 ± 3.57 ml. Thus, the normal range was 17.4 to 31.9 ml. This suggests that each country should establish its own normal range and that measurement of testicular size with this orchiometer is helpful in assessing the degree of sexual maturation and function in the male. DISCUSSION Normal testicular size in the United States was based on careful examination of volunteers in Rochester, NY, Richmond, CA, Little Rock, AR, and Mobile, AL (Table 2). From testicular mea- Table 2. Orchiometer Dimensions Orchiometer no. Longit,!dinal Transverse axis (volume) axis (longitudinal axis x %) ml mm mm Takihara et al. Testicular size, orchiometer 837

3 Figure 1 Complete orchiometer set. surements reported by others (Table 1), there are considerable variations in the values obtained according to the methods reported by other in vestigators. It is rather difficult to evaluate the exact size of the testis alone during life with indirect measurements, because the epididymis and scrotum may interfere with the measurement. Consequently, any numeric data are only of relative precision. The findings we obtained from 164 normal male subjects are in agreement with previous reports. 2-4 The differences in normal testicular size between the United States and Japan might be due to differences in the body weight or surface area of the subjects. All normal men had> 40 million sperm/ml. Historically, there have been two. methods of indirect measurement. One is measurement of - the longitudinal and transverse axis with calipers, an4 the other is comparative palpation with testicular models of known volume. Using cali.. pers, From Hansen and With 5 first measured the length and width of each testis and determined testicular size on the assumption that the testis was the shape of an ellipsoid. Lambert6 devised the empirical formula as follows: Testicular size (milliliters) = 0.71 x length x width x depth (thickness in anterior or posterior direction). Rundle and Sylvester3 believed that the manipulation necessary to exclude the epididymis introduced greater errors than the as838 Takihara et a1. Testicular size, orchiometer sumption that width and depth were the same. They measured only length and width; thus the size of the testis in milliliters was obtained by using the modified empirical formula of Lambert,6 i.e., testicular size (milliliters) = 0.71 x length x breadth squared. The majority of the workers who examined the patients used a comparative palpation method. 2, 3,7,8 Prader2 designed models having the exact form of ellipsoids, comprising 12 models with a volume of 1 to 25 ml. His method was adopted for the international longitudinal growth studies coordinated by the Centre International de I'Enfance. Schonfeld and Beebe8 obtained the volume of each wax model by water displacement and chose a graded series for further experimentation to determine the magnitude of perceptible differences at various points in the scale of volume. Those were 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.25, 1.5, 1.75,2.0,2.5, 3, 4, 5, 6, 8, 10, 12, 14, 18, and 25 ml. In their measurement, three readings were made for each testis, and their median was recorded as the estimate of its size. Their statistical analysis showed that the errors are not random and independent of volume but are correlated in two ways: first, negative errors tend to occur when large volumes are being estimated, and positive errors occur when small volumes are measured; second, the magnitude of the error varies directly with the volume being estimated. The determination of different diameters in an oval structure is a rather laborious, time-consuming procedure that may be uncomfortable for the patients, especially in the case of children and adolescents, since it involves considerable manipulations of their genitalia. In ' contrast, com- Figure 2 Single orchiometer.

4 'Co 'Co <D E E... A <D E E... <D <D () () as 12 as 12.. a. r=0.58 a. r=0.81.! '" <D <D a; a; 3: 3: >- 8-8.J:l >-.J:l : <D <D E 6 E 6 :::l :::l (5 (5 > >... as as "3 "3.2 () U; OLe I I I I I I ~ L I I I I I I <D <D o i Testicular Size Calculated by CaIi(:2rs(m!) B Testicular Size Measured by Punched-out Orchiometer (m!) Figure 3 (A), Correlation of testicular volumes measured by using calipers versus those determined by water displacement. (B), Correlation of testicular volumes measured by using the present orchiometer versus those determined by water displacement. parative palpation by the testis model with known volume is convenient and more acceptable, but not necessarily precise. 8 Stearns et al. 9 furthermore determined testicular size in 116 men both by measuring testicular length (mean of longest diameter of both sides in centimeters) with a caliper and by estimating the mean testicular size using the Prader orchiometer. They found a significant correlation between testicular length and size (r = 0.749, P < 0.001). This implies that the accuracy of conventional orchiometer can be improved by taking advantage of both techniques. Errors can be introduced when the length and breadth are measured separately, because the testis is soft and easily turned in the scrotum. Consequently, we have advocated the punched-out elliptical orchiometer,... E -; 20. ~ en....!!! :::l () :; 10 <D _ c:: CII <D -... :::i: Age Figure 4 Testicular size of male subjects from newborn to 80 years of age. which ensures measuring length and width at the same time. This elliptical orchiometer does, indeed, have the advantage of both techniques and is convenient, precise, and more accurate than the method using calipers (r = 0.58 versus r = 0.81). Recent advancement of ultrasonography provides high-resolution sectional images of the testis and adjacent structures Miskin and Bain 12 produced a clear picture of the testis and obtained a direct and accurate measurement of testicular width. Testicular width measured by ultrasonography was compared with that measured clinically with calipers. As expected, when measured manually, there is a slight overestimation of testicular width, probably related to the inclusion of subcutaneous tissue in the measurement. For routine clinical use, however, orchiometer measurement is more practical and economical than ultrasonographic measurement. Thus, we advocate the use of our orchiometer for the rapid and accurate assessment of testicular volume during physical examination. Acknowledgments. We wish to thank Dr. Yoshiyuki Schimizu and Dr. Yoshikazu Koshido, Department of Urology, Yamaguchi University School of Medicine, for the clinical management of the patients discussed, and Mrs. Sue Yells for assistance with the illustrations and manuscript. REFERENCES 1. Sherins RJ, Howards SS: Male infertility. In Campbell's Urology, Vol 1, Edited by JH Harrison, RF Gittes, AD Perlmutter, TA Stamey, PC Walsh. Philadelphia, W. B. Saunders, 1978, p 715 Takihara et al. Testicular size, orchiometer 839

5 r 2. Prader A: Testicular size: assessment and clinical importance. Triangle 7:240, Rundle AT, Sylvester PE: Measurement oftesticular volume: its application to assessment of maturation and its use in diagnosis of hypogonadism. Arch Dis Child 37:514, Laron Z, Zilka E: Compensatory hypertrophy of testicle in unilateral cryptorchidism. J Clin Endocrinol Metab 29: 1409, From Hansen P, With TK: Clinical measurements of the testes in boys and men. Acta Med Scand (Suppl) 142:457, Lambert B: The frequency of mumps and of mumps orchitis, and the consequences for sexuality and fertility. Acta Genet (Suppl) 2:1, Hurxthal LM: Hypogenitalism during the usual time of puberty. JAMA 136:12, Schonfeld WA, Beebe GW: Normal growth and variation in the male genitalia from birth to maturity. J Urol 48:759, Stearns EL, MacDonnell JA, Kaufman BJ, Padua R, Lucman TS, Winter JSD, Faiman C: Declining testicular function with age: hormonal and clinical correlates. Am J Med 57:761, Takihara H, Valvo JR, Tokuhara M, Cockett ATK: Intratesticular cysts. Urology 20:80, Gronvall S, Brunner N, Jacobsen GK, Holm HH: Ultrasound in the detection of testicular tumors. Int J Androl (Suppl) 4:185, Miskin M, Bain J: The use of echography in the evaluation of testicular disorders. In Progress in Reproductive Biology, Vol 3, Edited by J Bain, ESE Hafez, BN Barwin. Basel, S. Karger, 1978, p Takihara et ai. Testicular size, orchiometer