Long-term effects of vasectomy on pituitary-gonadal function in man

Reduced sperm yield from testicular biopsies of vasectomized men is due to increased apoptosis

OBJECTIVE

To compare sperm yields, apoptotic indices, and sperm DNA fragmentation from vasectomized men and fertile men undergoing vasectomy.

DESIGN

Testicular biopsies from vasectomized (n = 26) and fertile men (n = 46), were milked to calculate sperm/gram and also formalin-fixed to determine the numbers of developing sperm and incidence and intensities of testicular FasL, Fas, Bax, and Bcl-2. Testicular sperm DNA fragmentation was assessed using the alkaline Comet assay.

SETTING

An ART unit.

PATIENT(S)

Twenty-six men attending for intracytoplasmic sperm injection (ICSI) and 46 men attending for vasectomies.

MAIN OUTCOME MEASURE(S)

Spermatocyte, spermatid and sperm yields, Fas, FasL, and Bax staining.

RESULT(S)

Sperm yields from men vasectomized >5 years previously were markedly reduced compared to fertile men. Increased intensities of FasL and Bax staining were observed in the seminiferous tubules of vasectomy men. FasL positivity (percentage) also increased in Sertoli cells, and both FasL and Fas positivity (percentage) increased in primary spermatocytes and round spermatids of vasectomized men. Sperm DNA fragmentation, an end point marker of apoptosis, increased significantly in vasectomized men compared to fertile men.

CONCLUSION(S)

Reduced sperm yields after vasectomy are associated with increased apoptosis through the Fas-FasL and Bax pathways. Sperm after vasectomy displayed increased DNA fragmentation.

Stereological analysis of the human testis after vasectomy indicates impairment of spermatogenic efficiency with increasing obstructive interval

OBJECTIVE

To quantify germ cell loss and the extent of testicular fibrosis in vasectomized patients of varying obstructive intervals.

DESIGN

Retrospective study.

SETTING

Specialized male reproductive surgery and endocrinology service.

PATIENT(S)

Thirty-four vasectomized patients 1-20 years after surgery and 10 normal subjects.

INTERVENTION(S)

Thirty-four testicular biopsies taken at the time of vasectomy reversal (vasovasostomy). Control biopsies taken from 10 normal men at the time of vasectomy.

MAIN OUTCOME MEASURE(S)

Stereological assessment of testicular germ cell populations and testicular fibrosis.

RESULT(S)

Vasectomy caused a significant decrease in germ cells in the later stages of spermatogenesis, with significant reductions in pachytene spermatocytes (by 18%), round spermatids (by 40%), elongating spermatids (by 23%), and elongated spermatids (by 39%). The loss of spermatids showed a significant relationship with obstructive interval. A significant 2.7-fold increase in total (peritubular plus interstitial) fibrosis was observed, which showed a positive relationship with obstructive interval. Decreased germ cell populations and fibrosis did not seem to be related to sperm antibody levels nor to sperm counts obtained up to 2 years after vasovasostomy.

CONCLUSION(S)

Vasal obstruction results in significant reductions in germ cells in the later stages of spermatogenesis and increases in testicular fibrosis, both worsening with an increasing obstructive interval. Testicular damage after vasectomy might impact upon the prospects for reversal.

Possible biological mechanisms for a relationship between vasectomy and prostatic cancer

Four hypotheses have been reviewed, each of which might serve as a hypothetical biological explanation for a relationship between vasectomy and prostate cancer. The endocrine hypothesis is the only one of these with any firm data to support it, although the majority of the available data does not lend credibility to that theory. The other hypotheses are purely speculative with no hard data to support them. In conclusion, it seems highly unlikely, but not impossible, that there is a biological mechanism supporting a relationship between vasectomy and prostate cancer.

Does vasectomy have long-term effects on somatic and psychological health status?

All the major international articles on the somatic and psychological consequences of vasectomy published over the last 10 years have been reviewed and analysed. Although some experiments on animals have revealed harmful effects, none of the large-scale epidemiological studies has pointed to any increase in health risks (cardiovascular, hypertensive, psychiatric) in vasectomized men. The contradictions which arise between the clinical and large-scale epidemiological studies may be the result of methodological or experimental conditions. As our knowledge stands at present it can therefore be considered that vasectomy has no major effects on the physical or mental health of men.

The effect of vasectomy on the production of plasma luteinizing hormone and follicle stimulating hormone in man

A prospective study of plasma luteinizing hormone (LH) and follicle stimulating hormone (FSH) in 51 men before vasectomy and 10 days and 3 months after vasectomy revealed a trend to rise in LH 10 days after vasectomy normalizing after 3 months. The literature concerning alterations in LH and FSH after vasectomy is reviewed and different theories are discussed.

Vasectomy, cigarette smoking, and age at first sexual intercourse as risk factors for prostate cancer in middle-aged men

A population-based case-control study was conducted in men aged 60 or less to assess the risk of prostate cancer associated with vasectomy and other factors. Data were obtained from 216 case-control pairs by telephone interviews; this number represented 55% of all eligible cases. The matched pairs relative risk (RR) for vasectomy in ever married men was 1.4 with a 95% confidence interval (CI) of 0.9-2.3. There was a positive association between the number of years since vasectomy and prostate cancer risk (1-sided P = 0.01). Early age at first sexual intercourse was associated with increased prostate cancer risk (age less than 17 vs. 21+, RR = 2.3, 95% CI = 1.3, 4.0) but there were no consistent associations with number of sexual partners or frequency of sexual intercourse. Cigarette smoking was also associated with increased risk of prostate cancer (RR = 1.9, 95% CI = 1.2, 3.0) and there was a positive dose-response relationship with years of smoking (1-sided P = 0.001). We discuss the possible implication of the low response rate on each of these findings. To determine whether the association with vasectomy might have a hormonal basis, we compared levels of testosterone (T) and testosterone binding globulin-binding capacity (TeBG-bc) in 33 of the vasectomized control men with levels in 33 non-vasectomized controls of the same age, weight and height. T levels were higher in vasectomized than in non-vasectomized controls (1-sided P = 0.06). The ratio of T to TeBG-bc (an index of bioavailable T) was 13.5% higher in vasectomized men (1-sided P = 0.03).

Plasma reproductive hormones in normal and vasectomized Chinese males

Plasma reproductive hormones (testosterone, LH, FSH and prolactin) were measured in 298 normal healthy males aged 30-73 years from rural areas of Sichuan Province, People's Republic of China, and in 505 similar men vasectomized between 1 year and 25 years previously. Age-related increases in LH and FSH but not in testosterone or prolactin were noted in normal men. No adverse effects of vasectomy were observed apart from a 16% increase in mean LH levels in the vasectomized compared to non-vasectomized men of similar ages.

Pitfalls in using human chorionic gonadotropin stimulation test to diagnose anorchia

Previous studies have concluded that surgical exploration is unnecessary in genetic male subjects with nonpalpable tests who fail to respond to human chorionic gonadotropin. Lack of response suggested absent testicular tissue. We report on 2 patients thought to have anorchia because of lack of response to human chorionic gonadotropin stimulation. Testes were found in both patients. Genetic and phenotypic male subjects with nonpalpable testes who fail to have increased testosterone after human chorionic gonadotropin stimulation should undergo laparoscopy. If testicular structures are present at laparoscopy surgical exploration is indicated. Unresponsiveness to human chorionic gonadotropin may be evidence of nonexistent or dysfunctional Leydig cells rather than evidence of complete absence of testicular tissue.

Primary hypothyroidism of childhood: evaluation of the hypothalamic-pituitary gonadal axis before and during L-thyroxine replacement

Hypothyroidism is frequently associated with abnormal sexual development. To determine the longitudinal influence of thyroxine replacement on the hypothalamic pituitary gonadal axis, we studied five prepubertal hypothyroid girls and two boys before, and all the girls six weeks and one year after, thyroxine replacement. All girls showed significantly elevated basal gonadotrophin concentrations before treatment. Following one year of therapy, despite all girls having begun puberty, basal gonadotrophin concentrations were significantly decreased in the four euthyroid girls as compared with our normal pubertal girls. The fifth girl studied at one year was hypothyroid at the time of testing and her gonadotrophin values were increased even above previous basal values. Pretreatment serum TSH values inversely correlated with maximum pretreatment incremental LH (r = -0.54) and FSH (r = -0.52) responses to LHRH. Serum TSH values directly correlated with PRL concentrations (r = +0.82). Of the two hypothyroid boys evaluated, Patient 1 was mildly hypothyroid and showed normal prepubertal basal LH, FSH, testosterone and low normal LHRH responsiveness. Patient 2, who was more severely hypothyroid, had elevated basal gonadotrophin secretion and responsiveness to LHRH but prepubertal testosterone concentrations. These data indirectly show that thyroxine may increase the biological/immunological potency of gonadotrophins. The elevated gonadotrophin values in the hypothyroid state suggest that the metabolic clearance rate of gonadotrophins is prolonged. The more severe the elevation in TSH secretion, the more marked was the alteration in the hypothalamic pituitary axis in respect to PRL secretion and delta max LH and FSH response to LHRH. Replacement with thyroxine was followed by normal pubertal development, and normal pubertal oestradiol and PRL concentrations, despite low immunoreactive gonadotrophin secretion.

The long-term effects of vasectomy on sexual behaviour

Two hundred soldiers of the Sri Lanka Army who had undergone vasectomy at least 4 years earlier were interviewed by a pretested questionnaire to determine the incidence and nature of any changes in sexual behaviour after the operation. Fifty-six percent reported some change in their sexual behaviour after vasectomy. A decreased frequency of intercourse being reported by 15%, a decreased sexual desire by 19% and changes in sexual behaviour during intercourse by 33%. Seven percent reported that their wives had noticed an alteration in sexual behaviour after operation. In spite of these changes in sexual behaviour after vasectomy the majority of men (92%) reported satisfaction with the operation, which is an indication that changes in sexual behaviour cannot be attributed directly to vasectomy.

Lack of effect of vasectomy on peripheral gonadotrophin and steroid levels

In order to re-assess the possible hormonal consequences of male sterilization, the peripheral plasma levels of lutropin (LH) follitropin (FSH), and dihydrotestosterone sulphate (DHT-S) were measured in a group of 20 healthy men at weekly intervals in the month before and at bimonthly intervals up to 2 years after vasectomy. In addition, the levels of 14 steroids of gonadal and/or adrenal origin were measured before, and then every second month (12 subjects) or every sixth month (8 subjects) following vasectomy. No significant alterations were observed in the levels of any of the hormones studied. The results are interpreted as indicating that in the first 2 years following vasectomy in men there is no consistent or progressive change in the peripheral plasma levels of gonadotrophins or in a variety of steroids of testicular and/or adrenocortical origin.

Effect of vasectomy on the steroid profile of human seminal plasma

The effect of vasectomy on the steroid profile of seminal plasma was studied in 19 healthy men at 4-monthly intervals during a 2-year post-vasectomy period. The steroids analyzed by radioimmunoassays were: androstenedione (A), testosterone (T), dihydrotestosterone (DHT), oestradiol (E2) and the sulphoconjugated forms of pregnenolone (delta 5P-S), dehydroepiandrosterone (DHEA-S), testosterone (T-S), dihydrotestosterone (DHT-S), oestrone (E1-S) and oestradiol (E2-S). The quantitatively most important steroids present in the seminal plasma were DHEA-S, delta 5P-S and DHT-S. Vasectomy resulted in a significant but non-progressive reduction in DHT (40%) and T (23%) levels. The levels of E2, delta 5P-S and DHT-S also exhibited a smaller reduction following vasectomy. No significant changes were observed in the levels of the other steroids studied. The results are interpreted as suggesting that under normal conditions the bulk of the steroids present in the ejaculate is contributed by the accessory reproductive organs. In addition, a significant part of the DHT and T reach the ejaculate together with the sperm directly from the testis and/or epididymis. It is suggested that the normal steroid levels in seminal plasma established in this investigation could serve as reference values in the hormonal evaluation of male infertility.

Reduced activity of Mg2+- and Ca2+-dependent adenosine triphosphatase in seminal fluid of patients with oligozoospermia

Mg2+- and Ca2+-dependent ATPase activity, fructose and divalent cation concentrations were determined in seminal plasmas from men with oligozoospermic ejaculates and from those with normal sperm count. The mean activity of the Mg2+- and Ca2+-stimulated ATPase from the former was 59 nmol . 0.1 ml-1 . This is significantly (p less than 0.005) lower than for men with a normal sperm count (corresponding figure is 87 nmol . 0.1m1-1 . min-1). As regards the concentrations of Mg2+, Ca2+ and Zn2+ in the seminal plasmas from these two groups there was no significant difference. The same was also valid for the fructose concentrations. The Mg2+- and Ca2+-stimulated ATPase activity as well as fructose and divalent cation concentrations were also determined in seminal plasmas from men before and after vasectomy. After vasectomy, only the ejaculates devoid of spermatozoa were included in the comparative studies. No significant difference was observed between the seminal plasmas from men before and after vasectomy. These findings support the view that the Mg2+- and Ca2+-stimulated ATPase system does not derive from the spermatozoa. Possible explanations for the significantly lowered Mg2+- and Ca2+-dependent ATPase activity from patients with oligozoospermia are given.

Plasma testosterone, luteinizing hormone and follicle-stimulating hormone one day after vasectomy

Plasma testosterone, LH and FSH were measured in 20 healthy subjects prior to and one day after bilateral vasectomy. No significant change in these hormones was noted after surgery. These data suggest that the decrease in free testosterone index and FSH reported by others at one week post-vasectomy is probably not related to the effects of psychological stress, local anesthesia or surgical stress, either singularly or in concert. Further studies are indicated to evaluate the transient hormonal changes reported within the first few weeks following vasectomy.

The endocrine effects of vasectomy: a prospective five-year study

A prospective study of plasma luteinizing hormone (LH) and testosterone in 54 men for 5 years following vasectomy revealed no significant continuing alteration in either testosterone or LH. Plasma LH levels 1 year after operation were higher than preoperative levels but did not increase further. Stimulation studies (4 years postvasectomy) using human chorionic gonadotropin confirmed acceptable Leydig cell functional reserve.

Treatment of congenital virilizing adrenal hyperplasia patients with single and multiple daily doses of prednisone

Six patients with congenital virilizing adrenal hyperplasia were evaluated on single- and multiple-dose prednisone schedules. Each of the treatment periods was for one month. Patients were evaluated by 24-hour urinary excretion of 17-ketosteroids and pregnanetriol, as well as 0900 plasma concentrations of 17-hydroxyprogesterone, progesterone, and testosterone. By the criteria of urinary excretion of KS and PNT appropriate for chronologic age, three of the six patients were adequately controlled on prednisone given once a day. Prednisone administered twice daily at 12-hourly intervals either in equally divided doses or with a larger dose in the evening, however, resulted in adequate suppression in all patients. Because of the marked diurnal variation of plasma 17-OHP, the time of day that the sample is drawn is critical. Afternoon samples are often misleadingly low. Plasma 17-OHP concentration may reflect escape from therapeutic control sooner than urinary KS and PNT excretion. There was no correlation between 17-OHP and P values. Plasma concentration of T was not a reliable indicator of good control, since T values were often at prepubertal levels when urinary KS and PNT were elevated.

Endocrine effects of vasectomy

In order to provide information on the endocrine effects of vasectomy, unconjugated pregnenolone, dehydroepiandrosterone, androstenedione, testosterone, dihydrotestosterone, oestrone and oestradiol were analysed in the blood plasma of twenty Mexican men on two occasions before and 1, 3, 6 and 12 months after vasectomy. Vasectomy appeared to be associated with a significant decrease in the plasma levels of pregnenolone, dehydroepiandrosterone and androstenedione and a significant increase in the levels of dihydrotestosterone and oestrone. A probably significant increase in oestradiol levels took place 12 months after vasectomy but not before. No consistent changes were found in testosterone (up to 12 months) or in FSH and LH levels (up to 6 months) after vasectomy. The unconjugated steroids indicated above, except oestrone, were also estimated, whenever possible, in seminal plasma specimens obtained from thirty-nine subjects (including the twenty indicated above) on the same occasions. Vasectomy was associated with a highly significant decrease of seminal plasma dihydrotestosterone levels on all occasions and a significant decrease in androstenedione levels after 6 and 12 months. After 12 months there was a decrease in dehydroepiandrosterone and an increase in oestradiol; these changes were both probably significant. In another preliminary study, the levels of pregnenolone sulphate, dehydroepiandrosterone sulphate, testosterone glucuronide, testosterone sulphate and dihydrotestosterone sulphate were estimated before and 1 month after vasectomy in the seminal plasma of fourteen to seventeen subjects. Testosterone glucuronide fell, probably significantly, but other conjugates were unchanged. The data indicate that vasectomy may be associated with significant changes in the circulating and in seminal plasma levels of several steroids. The gradual nature of some of the changes observed suggests the necessity of conducting in several centres large-scale, long-term studies on vasectomized subjects and on a carefully matched control group. During the last decade vasectomy has been widely practised in several parts of the world as a method of fertility control. However, information on the endocrine effects of this intervention appears to be scanty. In most of the human studies reported, a small number of individuals were investigated and the studies have been confined to the assessment of the short-term effects of the operation. Moreover, the hormonal indices assessed by the various investigators have been limited, in most cases, to gonadotrophins and testosterone in blood. The present study was designed to assess in the same subjects the levels of a number of unconjugated steroids, FSH and LH on two occasions before and 1, 3, 6 and 12 months after vasectomy. The studies were extended to include steroid analyses in seminal plasma in the hope that such assays might yield information as to the effects of vasectomy on the distribution of steroids in the fluids of the male reproductive tract.