Indian Journal of Urology
: 2001  |  Volume : 17  |  Issue : 2  |  Page : 156--158

A study of the hypo-osmotic swelling test of spermatozoa in both fertile and infertile male subjects and its relationship with the standard spermiogram

Kingshuk Majumdar, Gita Rajagopalan, A Bupathy 
 Department of Obstetrics and Gynaecology, Jawaharlal Institute of Postgraduate Medical Education and Research, Pondichery, India

Correspondence Address:
Kingshuk Majumdar
Plot No. 31, 4th Cross, Thanthai Periyar Nagar Extension, Pondicherry - 605 005


Objective: To compare the hypo-osmotic swelling test (HOST) of spermatozoa with the standard spermiogram in both fertile and infertile male subjects. Materials and Methods: The HOST was performed on 50 men of proven fertility and 51 infertile men. The results from both the groups were compared with the standard spermiogram. Study Design: Prospective case-control study. Analysis: The statistical analysis was done using the Karl Pearsons coefficient of correlation. Results: The HOST values were higher in the fertile group. The correlation between hypo-osmotic swelling and semen variables was higher in the infertile group than in the fertile group. 2 patients in the infertile group with greater than 50% hypo-osmotic swelling got their spouses pregnant during the study period. Conclusion: The HOST is inexpensive, easy to per­forrn and can be used to evaluate sperm tail function. It can also be used to predict the fertilizing potential of the semen sample.

How to cite this article:
Majumdar K, Rajagopalan G, Bupathy A. A study of the hypo-osmotic swelling test of spermatozoa in both fertile and infertile male subjects and its relationship with the standard spermiogram.Indian J Urol 2001;17:156-158

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Majumdar K, Rajagopalan G, Bupathy A. A study of the hypo-osmotic swelling test of spermatozoa in both fertile and infertile male subjects and its relationship with the standard spermiogram. Indian J Urol [serial online] 2001 [cited 2022 Aug 12 ];17:156-158
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The analysis of semen is a major tool in the evaluation of male infertility. The standard semen variables for the diagnosis of fertility/infertility are often insufficient by themselves, unless one of them is extremely low. For a more comprehensive evaluation of the ejaculate, a large number of assays like the HOST have been developed. [1] The hypo-osmotic swelling test assesses the functional integrity of the sperm plasma membrane. Fluid transport occurs across an intact plasma membrane under hypo­osmotic conditions until equilibrium is reached between the inside and outside of the cell. Due to the influx of fluid, the cell will expand causing a bulging of the plasma membrane. The fibres of the sperm tail are normally closely surrounded by the plasma membrane. Curling or bending of the tail fibres will occur within the plasma membrane follow­ing influx of fluid. This is best visualized by phase contrast microscopy. Spermatozoa that show a curled tail are also called "swollen". Only spermatozoa with a chemically and physi­cally intact membrane will show tail curling under hypo-os­motic conditions. The plasma membrane of a spermatozoon is also essential for capacitation, acrosome reaction, binding of the sperm to the egg surface and fertilization. The HOST is easy to perform, inexpensive, reliable and can also give an idea about the fertilizing potential of the ejaculate.

In the present study, the hypo-osmotic swelling test was performed in both fertile and infertile male subjects and cor­related with the standard semen variables. Most studies on the HOST have involved both fertile and infertile male sub­jects. However, the present study stands out because the fer­tile group consists of men with proven fertility of short duration (3 months), which is equal to a single spermatogenesis cycle.

 Materials and Methods

Male partners of 51 infertile couples attending the infertil­ity clinic run by the Department of Obstetrics and Gynaecol­ogy of JIPMER Hospital. Pondicherry were investigated from November 1993 to June 1995. There was no obvious cause for infertility in the female partners of the 51 infertile couples after examination and routine diagnostic investigations. Dur­ing the same time period 50 men of proven fertility, who had got their spouses pregnant within the last 3 months were taken as the control group. The men taken in the control group had got their spouses pregnant without intervention or investiga­tion for infertility. The male partners of both the groups were matched with respect to age and occupation.

The semen analysis was performed after 3 days of sexual abstinence by the methods described in the laboratory manual of the World Health Organization. [2] A viability test was also performed as described by Eliasson et al. [3]

The hypo-osmotic swelling test was performed as de­scribed by Jeyendran et al (1984). [1] A total of 200 sperms were counted and the mean score was calculated. The hypo-osmotic swelling test was performed using an Olympus phase contrast microscope. Depending on the mor­phological changes of spermatozoa when subjected to hypo-osmotic stress, the swelling patterns were labelled from type `a' to type `g'.

Statistical Analysis:

The statistical analysis between the HOST and the dif­ferent semen variables in the fertile and infertile groups was done using Karl Pearson's coefficient of correlation.


The average HOST score was 66.8% in the fertile group and 32.0% in the infertile group. Type `b' and `g' swell­ing patterns were the commonest in both the groups.

The Karl Pearson's coefficient of correlation between the total hypo-osmotic swelling and sperm motility in the infertile group was highly significant (P of the patients in the infertile group showed less than 60% hypo-osmotic swelling and 68.6% showed less than 50% hypo-osmotic swelling. No patients in the fer­tile group showed less than 50% hypo-osmotic swelling.

In the infertile group, 16 patients (31.4%) had >50% hypo-osmotic swelling scores of which 2 patients (12.5%) got their spouses pregnant during the study period.


The sperm penetration assay is widely accepted for as­sessment of the fertilizing capacity of human spermato­zoa. However, this test is expensive, time consuming, complex and labour intensive. Therefore, an inexpensive, simple and reliable test would be most ideal.The hypo­osmotic swelling test fulfils most of the above criteria and can be widely used.

Most investigators have noted that [4] No difference in pregnancy rates were noted between women whose partners had sub­normal, normal or superior spermiograms as long as the results of the HOST were >50%. [5] The high percentage of low HOST scores in the infertile group is because only men with no obvious cause for infertility in their female partners were included in this group. The study group therefore comprised mainly of men with either male fac­tor infertility or with idiopathic infertility.

The higher coefficient of correlation in our study be­tween the HOST values and sperm count in the infertile group could be because of most oligozoospermic samples showing a low HOST score. This is in variance compared to most studies, though some investigators have found a significant correlation between these 2 variables. [6],[7],[8]

The correlation between sperm swelling and motility was found to be greater at a lower percentage of sperm swelling ( [1] The HOST correlates with motility, particularly in oligo-, astheno-, and teratozoospermic semen samples. [9] Total swelling and type `b' swelling correlated highly with mo­tility in our study.

A small but significant correlation has been found be­tween sperm swelling and sperm morphology by most in­vestigators. Colpi et al, [10] found mid-piece abnormalities to correlate with the HOST. We found no correlation be­tween any Specific morphologic abnormality and the to­tal HOST score.

The parameter of sperm viability in hypo-osmotic swell­ing (VHOS) may be a more useful functional test and may eliminate many false positive and false negative results in the HOST. [11] Though the HOST and viability test assess different parameters of the spermatozoon they show a sig­nificant correlation coefficient with each other. A high correlation coefficient was also noted in our study.


To conclude, the HOST may help to identify infertile subjects with subnormal spermiograms but a normal HOST score who are likely to benefit from assisted reproductive techniques. Also, infertile subjects with a normal spermio­gram may have an abnormal HOST which could explain the cause for their infertility.


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2World Health Organization. WHO Laboratory Manual for the Ex­amination of Human Semen and Semen-Cervical Mucus Interac­tion. 3rd Edn. 1992.
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