N. Rehan  ( National Health Survey of Pakistan, Pakistan Medical Research Council, Islamabad. )

Semen characteristics were studied among 200 fertile Pakistani men aged 24 to 48 years. Each subject had fathered atleast two children. The mean±SD values of volume, sperm density, motility percentage, grade of motility and percentage of oval sperms were 3.11±1.2 ml, 58.21±26.41 millIon/mi, 61 .2±21 .3%, 3.01±0.94 and 70.2±15.36% respectively. There was no deteriorating effect of age on semen quality except some decrease in semen volume. The comparison has been made with studies from other countries (JPMA44:62, 1994).

Semen analysis is the most important test to assess the fertility potential of a male. The decision to institute any therapeutic intervention hinges on the result of semen analysis. Unless reference values are available for the population being dealt with, the interpretation of results becomes difficult. A perusal of pertinent literature reveals that the maximum number of studies on the semen analysis relate to Caucasian population of USA^1-4. Through there are certain reports from Europe^5-7 and South America⁸, yet there is a paucity of studies outlining the reference values for oriental and African populations. The present study is the first report to define reference values of semen parameters of fertile Pakistani males.

The study is based on the semen analysis of 200 Pakistani males of proven fertility, who voluntarily participated in the study. Each individual has fathered atleast two children. The semen specimens were col­lected by masturbation after a minimum abstinence of 3 days and analyzed within 2 hours of production accord­ing to WHO’s standardized methods⁹.

The age of the study population ranged from 24 to 48 years with a mean (± SD) of33. 17±4.96 years. The age distribution of the subjects is shown in Table I.

The mean longitudinal diameter of testes was 4.35±0.43 cm for left testes and 4.37±0.42 cm for right testes, whereas the corresponding figures for transverse diameter were 2. 47±0.50 cm and 2.52±0.14 cm respec­tively (Table II).

The results of semen analysis are summarized in Table III.

The volume of the semen ranged from 1 ml to 8.2 ml. The frequency distribution is shown in Figure 1.

The mean volume was 3.1±1.2 ml. In 76% cases the volume ranged between 1 ml and 5 ml. The sperm density, i.e., sperm count/mi ranged from 13 to 184 millions. The mean sperm density was 79.48± 33.8 millions when arithmetic mean was calcu­lated and 58.21±26.41 millions according to geometric mean (Figure 2).

The percentage of actively motile sperms varied from 11 to 92%. The mean motility was 61.2±21.3%. The relative frequency distribution is shown in Figure 3.

The grade of motility ranged from 1 to 4 with a mean value of 3.01 ± 0.94. The percentage of sperms with oval forms ranged from 46 to 93% with a mean value of 70.2±15.36% (Figure 4).


Table IV shows the semen characteristics among different age groups. Except a progressive decrease in semen volume with advancing age, there was no sig­nificant change in other parameters.

The mean testicular size of fertile Pakistani males is the same as reported for Caucasian population. According to Williams and Warwick¹⁰, the average dimensions of testes ranged from 4 to 5 cm in length, 2.5 cm in breadth and 3 cm in antero posterior diameter. In fact there is a dearth of studies on this aspect of andrology. The few studies, which exist, have not used uniform scales of measurements and as such the comparison becomes difficult.

Table V shows the comparisons of our findings with other reports^{1-8,  11-13}. Although the findings of the present study are similar to other studies from various continents of the world, yet there were few note worthy differences. In our series, the percentage of fertile men with a sperm density of less than 20 million/mi was lower (2%) as compared to various studies from West^1-7. MacLeod and Gold¹ reported that only 5% of his patients had a sperm density of less than 20 million/ml. Rehan and Sobrero has put this figure at 7%². In the studies of Nelson and Bunge¹⁴ and Smith and Steinberger⁴, cor­responding values are 20.12% and 18.35% respectively, while the researchers from Kenya¹¹ found that 4% African population has a sperm density of less than 20 million/mi. Wang et al¹² in their study of 1239 Chinese men found that8% had a sperm of less than 20 million/mi. No case of polyzoospermia, i.e., sperm density of more than 250 million/ml was seen in the present study. The frequency distribution of motile and oval sperms in the present series was similar to that observed among Caucasians and Chinese. The mean sperms density in our series (58 million/ml) is in total agreement with the findings of Rajan from India¹³, who also reported in mean sperm density of 58 million/ml Our figures also agree with the observations of Akhtar¹⁵. Our findings agree with other reported series^4,6,14 that with advancing age the parameter most likely to suffer is semen volume. These findings however differ from the results reported by Schwartz et al⁵ who noted decreased motility and morphology. Inspite of these differences, all andrologists agree that the fertilizing capacity of sper­matozoa per se, does not deteriorate with age.

1. MacLeod, J. and Gold, R.Z. The male factor in fertility and infertility IlL Analysia of motile activity in the spermatozoa of 1000 fertile men and 1000 men in infertile marriage Fertill. Steril., 1951;2:187-204.
2. Rehan, N.E., Sobrero, AJ. and Fertig. J.W. The semen of fertile men: statistical analysis of 1300 men. Fertil. Steril., 1975;26:492-502.
3. Sobrero, A.J. and Rehan, N.E. The semen of fertile men. Semen characteristics of 100 fertile men. Fertil. Steril., 1975;26:1048-56.
4. Smith, K.D. and Steinberger, E. What is oligospermia. In: P. Troen, H.R. Nankin (eds). The testis in normal and infertile men, NewYork, Raven Press, 1977, pp. 489-503.
5. Schwartz, D., Mayauk, M.i., Spira, A. et at Studyofa group of 984 fertile men. Relation between age (20.59) and semen characteristics. Int.J.Androl., 1981;4:450-56.
6. Abyholm, J. An andrological atudy of 51 fertile men. Int.J.Androl., 1981;4:646-56.
7. Freischen, P., Millet, D., Venderfy, E., etal. Relationship between sperinatogenesis and gonadotropin levels.J.Clin.Endocrinol. Metab., 1982;43:1003-11.
8. Bahacnondea, L, Abdelmassih, R. and Dachs,J.N. Surveyof 185 sperm analyses offertile men in an infertility services. Int.J.Androl., 19792:526-33.
9. World Health Organization. Laboratory manual for the examination of human semen and semen-cervical interaction. Singapore, Press concern, 1980.
10. Williams, P.L, Warwick, R. Gray’s anatomy. 36th ed. London, Churchill Livingstone, 1980, pp. 1410.17.
11. Obwaka, J.M., Mati, J.K.G., Lequin, R.M., et al. Baseline studies on semen and hormonal parameters in fertile black males in Kenya. J.Obstet.Gyn. East Ceni Afric., 19821:96-99.
12. Wang, C., Chan, S.Y.W., Leung A. et al. Cross-sectional study of semen parameters a large groupof normal Chinese men. Int.J.Androl., 1985;8:257-74.
13. Rajan, R. Etiology of male infertility: analysis of 210 consecutive cases. J.Obstet. Gynae. India, 1977;27:371-75.
14. Nelson, C.K.K and Bunge, R. Semen analysis: evidence of changing parameters of male fertility potential. Fertil. Steril., 1974;25:503-7.
15. Akhtar, M.S. Semen analysis in fertile and infertile Pakistani men and effect of varicocelectomy on semen quality (MS dissertation). Labore, University of Punjab, 1988, p. 136.