|Year : 2016 | Volume
| Issue : 3 | Page : 92-95
Testicular Volume Measurement: Comparison of Prader's Orchidometry, Ultrasonography, and Actual Volume by Water Displacement
Suresh Bhat, Manjunath Sathyanarayanaprasad, Ashwin Giridhar, Yateesh Srinivasa, Fredrick Paul
Department of Urology, Government Medical College, Kottayam, Kerala, India
|Date of Web Publication||4-Aug-2016|
Department of Urology, Government Medical College, Kottayam - 686 008, Kerala
Source of Support: None, Conflict of Interest: None
Objectives: To assess the accuracy of Prader's orchidometer and ultrasonography in estimating the volume of testis against the actual volume of testis as measured by Archimedes principle of water displacement. Subjects and Methods: Fifty-six patients with advanced prostate cancer had an estimation of testicular volume by Prader's orchidometer by the same urologist and ultrasonography by the same radiologist. Lambert's formula was used for calculating the volume of testis. All patients underwent bilateral orchiectomy, and the actual volume of the testes was estimated by the water displacement method. Results: Mean age of patients was 71.53 years. The reliability of both the methods was calculated by Bland-Altman plot. The discrepancy of individual measurement and the bias (average discrepancy) was calculated for each method separately, and the plot was derived. In both the plots, the values were more concentrated around the value 0, showing that both were reliable in measuring the volume accurately. Conclusions: The volume of testis measured by Prader's orchidometer correlated with that measured by ultrasonography as well as the actual volume measured by water displacement method. This method is hence useful in office practice, community screening, adolescent clinics, and teen clinics.
Keywords: Infertility, orchiectomy, ultrasonography
|How to cite this article:|
Bhat S, Sathyanarayanaprasad M, Giridhar A, Srinivasa Y, Paul F. Testicular Volume Measurement: Comparison of Prader's Orchidometry, Ultrasonography, and Actual Volume by Water Displacement. J Integr Nephrol Androl 2016;3:92-5
|How to cite this URL:|
Bhat S, Sathyanarayanaprasad M, Giridhar A, Srinivasa Y, Paul F. Testicular Volume Measurement: Comparison of Prader's Orchidometry, Ultrasonography, and Actual Volume by Water Displacement. J Integr Nephrol Androl [serial online] 2016 [cited 2019 Dec 11];3:92-5. Available from: http://www.journal-ina.com/text.asp?2016/3/3/92/187793
| Introduction|| |
Eighty to ninety percent of testicular volume is contributed to by semeniferous tubules which contain the germ cells and the Sertoli cells. A small testis is therefore an indirect evidence of poor testicular function. Hence, reliable and accurate determination of testicular volume are of benefit in evaluating a patient with a variety of testicular growth, development and functional disorders such as undescended testis, attainment of puberty, varicocele, and subfertility.
Several methods have been described to estimate the volume of testis. These include ultrasonography, orchidometry, calipers, etc., Most of the studies have shown the ultrasonographic (US) method to be the most accurate. However, some studies have shown the orchidometric method to be as good as US method. As orchidometric method is simple, convenient, quick, and cost-effective, this method is equally preferred for quantitative assessment of testis.
This study attempts to compare the accuracy of orchidometric and US methods with the actual volume measured by water displacement.
| Subjects and methods|| |
This is a hospital-based cross-sectional study conducted for a period of 12 months in patients with advanced prostatic adenocarcinoma undergoing bilateral orchidectomy as a form of androgen deprivation therapy.
Ethical approval was obtained from the Institutional Review Board of the Hospital. Patients with hydrocele, painful testis, and edematous scrotum or other scrotal masses were excluded. Moreover, those with testicular volume more than 25 mL were excluded since the higher limit of Prader's orchidometer (PDO) is 25 mL. After obtaining informed consent, all subjects who qualified for the study had their scrotum and contents examined, and the testicular volumes measured with a PDO. The testis was isolated and distinguished gently from the epididymis. The skin over scrotum was gently stretched taking care not to compress the testis. Using the orchidometer side by side, the manual comparison between the testis and the beads was made to identify the bead most similar in size to the testis; this indicated the testicular volume.
High-frequency US of 7.5 MHz transducer was used. Ultrasonography was done by a single evaluator for all the cases. Testes were scanned using light pressure to avoid distorting the testicular shape, and grayscale images of the testes were obtained in the transverse and longitudinal planes. At least, three separate transverse and longitudinal images of each testis were recorded, and the testicular length, width, and height were measured using electronic calipers without the inclusion of the epididymis. Testicular volume was calculated using the formula of Lambert: Length × weight × height × 0.71.
Bilateral orchiectomies were performed under spinal or local anesthesia. Volume of each testis was measured using Archimedes principle of water displacement. Each testis was separated from the epididymis and all surrounding layers and placed in a beaker completely filled with water up to the brim. The volume of displaced water was measured which indicated the actual volume of the testis.
Both PDO volume measurements and US measurements were tabulated and compared with the actual volume and each other.
The agreement of PDO and US with actual measurement was found out by drawing Bland-Altman plot where X axis represents the mean of the measurements and Y axis, the difference between two paired measurements. The agreement was quantified by constructing limits of agreement (mean of differences ± 1.96 standard deviation of differences). The Bland and Altman plot was drawn for finding out an agreement between PDO and actual as also between US value and actual measurement. Bland and Altmann recommended that 95% of the data points should lie within ± 1.96 standard deviation of the mean difference.
| Results|| |
Fifty-six patients were included in the study, with a total number of testes being 112. The mean age of patients was 71.53 years. The discrepancy of individual measurement and the bias (average discrepancy) were calculated for each method separately [Table 1].
|Table 1: The 95% limits of agreement for Prader's orchidometer and ultrasonographic |
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Bland-Altman plot was constructed between testicular volume measured by PDO and actual measurement. The mean and standard deviation of the differences were 1.52 and 2.019, respectively [Table 1]. The calculated 95% limits of agreement (mean of the differences ± 1.96 standard deviation) were −2.44 to 5.48. From the plot [Figure 1], it was clear that maximum values were within these limits and only four values were outside these limits.
Similarly, Bland-Altman plot was drawn for analyzing agreement between US value and actual value. The mean and standard deviation of differences were −1.90 and 2.54. The 95% limits of agreement were −6.96 to 3.02 [Table 1]. Here also, the Bland-Altman plot showed wider limits of agreement with very few values outside the limits of agreement [Figure 2].
|Figure 1: Bland-Altman plot with the representation of confidence interval limits for mean and agreement limits|
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|Figure 2: Bland and Altman plot with the representation of confidence interval limits for mean and agreement limits|
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| Discussion|| |
Precise measurement of testicular volume is important for evaluating testicular function because 80-90% of testicular volume is contributed to by seminiferous tubules and hence indirectly represents the quality of spermatogenesis. Estimation of testicular volume is essential in various clinical conditions in urology like monitoring of testicular development in boys with delayed puberty, varicocele, and following orchidopexy and varicocelectomy. In boys, testicular enlargement is the first sign of the onset of puberty. Up to puberty, testicular volume is about 4 mL. Delay in puberty can be identified and appropriate early referrals can be made. Estimation of the testicular volume is also useful in differentiating obstructive (normal volume) and nonobstructive (low volume) azoospermia.
In infertile patients, testicular volume predicts the quality of semen. Using punched out orchidometer, Arai et al. showed that when the total testicular volume was 30 cc, 20 cc, and 10 cc, these infertile patients had normal, severe oligospermia, and azoospermia, respectively. 
The PDO is the most popular means of measurement of testicular volume. Other methods are US, punched out orchidometry, and Seager's calipers. The advantages of PDO are that it is simple to perform, convenient, cheap, rapid, and needs hardly any expertise. This method is ideal in the outpatient clinics. However, the disadvantage is that it may overestimate the testicular volume because of intervening scrotal layers.
Schiff et al. in 159 patients presenting for infertility found no difference in the volume of testes estimated by US and PDO. Mean right testis volume was 18 ± 9 cc by US versus 18 ± 6 cc by PDO (P = 0.5); mean left testis volume was 17 ± 6 by US and 17 ± 8 cc by PDO (P = 0.8). 
Sakamoto et al. found a strong correlation between the actual volume of testis and that measured by PDO (P = 0.0001).  Paltiel et al. on the other hand did not find a statistically significant correlation between PDO and actual testicular volumes (P = 0.12).  Takihara et al. using punched out orchidometer reported good correlation with actual testicular volume. 
Mbaeri et al. in their study found that PDO overestimated testicular volume by about 2.66 ± 2.37 mL. In this study, it was found that PDO volume measurements correlated strongly with the actual testicular volumes measured by water displacement using Pearson correlation coefficient (P = 0.0001).  Goede et al. in 53 boys found a strong correlation between volume measurement by the orchidometer and US.  Kwak et al. in 457 adult males reported that when testicular volume was 15 mL or less, the testicular volumes measured by PDO (13.29 ± 1.94 mL) were significantly smaller than those measured by US (14.83 ± 2.76 mL). In contrast, the group with over 15 mL did not show any significant difference in the volumes measured by PDO (21.21 ± 2.58 mL) versus US (20.77 ± 4.26 mL). 
Ultrasonography is considered to be the best method to measure the volume of testis by many. However, it is costly, time-consuming, and may be inconvenient for the patient. Another disadvantage is that there are several formulae to calculate the actual volume giving different values. During US measurement, the test is easily becomes compressed, resulting in distortion of shape and dimensions. In addition, if the axis of the testis is not perpendicular when using US, the ellipsoid formula is not accurate. The shape of the testis is neither uniform nor necessarily ellipsoid, as has been proposed when applying the different formulae in use. To overcome these disadvantages, Shiraishi et al. advised usage of punched out orchidometer. In their study, the volume of testis measured by punched out orchidometer very closely correlated with the actual volume as measured by water displacement method.
Conditions such as adolescent varicocele and delayed puberty need to be diagnosed early as appropriate early referrals can be made. As most of the outpatient departments are busy, health workers can be trained to do orchidometry to screen adolescents for identification of conditions that need timely referral. The method is also practical in office practice, community screening, adolescent clinics, and teen clinics.
| Conclusions|| |
The volume of testis in adults as measured by PDO correlated with that measured by US, as well as the actual volume measured by water displacement method. As it is a cost effective, rapid and simple method with minimal training required, this can be done in clinics even by a technician.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
| References|| |
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[Figure 1], [Figure 2]