Earlier testing after vasectomy, based on the absence of motile sperm

Vol. 59, No.2, February 1993

FERTILITY AND STERILITY Copyright

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1993 The American Fertility Society

Printed on acid-free paper in US.A.

Earlier testing after vasectomy, based on the absence of motile sperm

Ian S. Edwards, M.B., B.S.* Cronulla Private Medical Clinic, Cronulia, New South Wales, Australia

Objective: To review the results of postvasectomy testing when clearance was based on the absence of motile sperm and to compare them with regimens based on complete azoospermia. Design: A review of 2,260 seminal assay results from 3,178 consecutive vasectomies performed during a 17-year period. Setting: An outpatient vasectomy service in a private group practice in suburban Sydney. Results: Clearance was given sooner and with less testing than with other reported regimens, without loss of reliability. Conclusions: Testing can be done 4 weeks after vasectomy, regardless of the number of postvasectomy ejaculations. If specimens are examined within 12 hours of collection, clearance may safely be given if motile sperm are absent. Repeat tests are essential if any motile sperm remain but are not needed if only nonmotile sperm are found. Fertil SterilI993;59:431-6 Key Words: Postvasectomy semen examination, vasectomy testing, sperm motility

Regimens for testing after vasectomy have long been a matter of debate. There is no dispute that seminal assays should be done to detect failures and to prove sterility. They are necessary because operators can fail to occlude the vas, because pregnancies can occur from residual sperm, and because vasa can recanalize. There is, however, no consensus about the number of tests, when they should be done, how they should be done, or how they should be evaluated. In part, this reflects legitimate differences of opinion about social, economic, and medico-legal priorities (1), Nevertheless, the writer's experience suggests that the extreme caution of some regimens may be unnecessary. Vasectomy is often chosen by people who have found other methods of birth control unsuitable, For many of them it will then be unsatisfactory to have the process of postoperative testing prolonged for months. Customary regimens (2-7) do not start testing until 2 to 4 months after vasectomy. They

Received June 29, 1992; revised and accepted October 21,1992.

* Reprint requests: Ian S. Edwards, M.B., B.S., 19 Gerrale Street, Cronulla, New South Wales 2230, Australia. Vol. 59, No.2, February 1993

require complete azoospermia to be demonstrated, often in at least two consecutive specimens. As a result, no one gets the "all clear" before 3 months and many remain unsure of the success of their vasectomy for some months after that. Some abandon testing without ever being given an assurance of sterility. In contrast, men in the regimen suggested here could almost all, if they wished, have clearance within 1 month and most, in fact, did so within 6 weeks of vasectomy. This regimen depends on men submitting specimens that can be examined for motile sperm within 12 hours of collection. Facilities allowing this are accessible in most Australian cities, It also depends on clinicians accepting that nonmotile sperm will not generate pregnancies. There is ample evidence for this proposition (2-4, 8-10), which is further supported by the data presented here. MATERIALS AND METHODS

In a 17 -year period since 1975, 3,178 vasectomies were performed under local anesthesia by the writer in a private clinic in suburban Sydney. The Schmidt technique (11) was used: no section of vas was exEdwards Earlier testing after vasectomy

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Table 1

Time After Vasectomy That Specimens Were Actually Submitted* By 3 weeks (24 days)

By 4 weeks (31 days)

By 6 weeks

By 14 weeks

57 (14) 229 (34) 33 (3)

112 (28) 428 (64) 312 (26)

230 (58) 571 (86) 817 (68)

376 (95) 647 (97) 1124 (94)

Suggested time After 10 ejaculations (n = 397) After 3 weeks (n = 665) After 4 weeks (n = 1198)

* Values are number of specimens; values in parentheses are percents.

cised, the severed ends were sealed by intraluminal cautery of about 2 mm without ligatures, and the sheath was closed over the prostatic end, leaving the testicular end outside the sheath. For the most recent 1,811 cases, this method was modified to an "open-ended" method (12), identical except that the testicular end of vas was not sealed. Patients were told to collect an ejaculation specimen at home in a container provided by the laboratory and leave it at a pathology collection center as soon as it was convenient. The specimen was then taken to a laboratory where at least 30 high-power fields (HPFs) were examined. If no sperm were seen in the wet film, some laboratories would centrifuge and re-examine the specimen. The reported sperm count included any sperm motility and the time interval between collection and examination of the specimen. In the earliest part of the period under review, men were asked to collect a specimen after 10 ejaculations following vasectomy. During a later period, specimens were requested at about 3 weeks after vasectomy. Most recently, the time suggested has been 4 weeks after vasectomy, regardless of the number of ejaculations. Further specimens were always requested if any motile sperm were reported, however few. If no sperm were seen or if only nonmotile sperm were found, provided that the specimen had been Table 2

examined within 12 hours of collection, the result was taken to indicate sterility. When large numbers of nonmotile sperm were found, the test was not routinely repeated, but in five cases another assay was done.

RESULTS Of the 3,178 men having vasectomies, 2,260 (71 %) submitted specimens for assay. Table 1 shows the number of weeks after vasectomy that men actually submitted specimens and compares the groups asked to do so after 10 ejaculations or after 3 weeks or 4 weeks. Detection of Failures

Five failures are known. One was operative: the vas on one side was severed but not properly closed. The other four followed routine uncomplicated operations and were apparently the result of spontaneous recanalization. Two were early recanalizations, i.e., detected by the continuing presence of motile sperm in postvasectomy tests. One was a late recanalization, detected by a pregnancy. Another was also detected by a pregnancy, but because no postvasectomy specimen had been submitted, the time of recanalization is unknown. Table 2 shows the assay results in each of these cases, expressed in millions per milliliter, or if <1

Assay Results in Vasectomy Failures

Cause 1. Operative

2. Recanalized 3. Recanalized 4. Recanalized (late) 5. Recanalized

1st assay

2nd assay

6 weeks: 65 X 10 6/mL, 60% motile 6 weeks: 1/10 HPF,* 5% motile 26 weeks: 1/2 HPF, 40% motile 5 weeks: 35 X 10 6/mL, 7% motile (Not tested)

16 weeks: 27 X 10 6 /mL, 60% motile 10 weeks: 3 X 10 6 /mL, 25% motile 29 weeks: 1/5 HPF, 50% motile 8 weeks: 1/6 HPF, 0% motile 18 months: 42 X 10 6 /mL, 58% motile

3rd assay

14 weeks: 2 X 10 6/mL, 7% motile

4th assay

20 weeks: 3 X 10 6/mL, 30% motile

12 months: 12 X 10 6 /mL, 50% motile

* HPF indicates numbers less than one sperm per high-power field (l/HPF is approximately 1 million/mL).

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Earlier testing after vasectomy

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Table 3

Result of Assay Related to Time of Testing* At 3 weeks (n = 324)

No sperm (n = 1,016) Nonmotile only (n = 1,207) Motile sperm remaining (n = 33)

At4 weeks (n = 534)

At 5 to 6 weeks (n = 761)

At 7 to 14 weeks (n = 525)

At >14 weeks (n = 112)

95 (29)

194 (36)

333 (44)

303 (58)

91 (81)

213 (66)

333 (62)

420 (55)

220 (42)

21 (19)

8 (1.1)

2 (0.4)

16 (4.9)

7 (1.3)t

* Values are number of assays; values in parentheses are percents.

0(0)

t 95% confidence interval for the percentage as 0.3% to 2.3%.

Assay Results with Only Nonmotile Sperm

X 106 /mL as numbers per HPF, with any motility as a percentage (%motile).

When only nonmotile sperm were found, counts ranged from one sperm/l00 HPF to 33 X 106/mL, the great majority being <1 X 106 /mL. In five cases the initial test showed a count of 16 to 33 X 106 nonmotile sperm. All of these repeat tests after a few weeks showed a marked reduction in numbers and again no motile sperm.

Assay Results Related to Time of Testing

Table 3 compares the assay results obtained for specimens submitted at different times after vasectomy (excluding four failures shown in Table 2). Assay Results with Motile Sperm

DISCUSSION

During the period under review, of the 2,260 men tested, 33 (1.5%) were found to have residual motile sperm when first tested. In most ofthem, the counts were <1 X 106 /mL, with motility:::;; 5%, and on repeat testing, the men had azoospermia or only few nonmotile sperm. A few men had large numbers of motile sperm when first tested: the results of their assays are shown in Table 4. The longest time after a successful vasectomy at which motile sperm were still present was 9 weeks. Table 4

1 2

3 4 5 6 7

8 9

10

This study confirms the observation of other writers that the number of residual sperm found in postvasectomy tests varies greatly between individuals (1), with a few men retaining surprisingly large numbers (2). Although the differences are interesting, only one feature of the test results is of practical clinical importance: the presence or absence of motile sperm. If motile sperm are present, sterility has yet to be achieved.

Assay Results of Cases With Many Residual Motile Sperm 1st assay

2nd assay

4 weeks: 8 X 106 /mL, 50% motile 7 weeks: 2 X 10 6/mL, 28% motile 3 weeks: 26 X 10 6/mL, 69% motile 3 weeks: 30 X 10 6/mL, 65% motile 4 weeks: 198 X 10 6/mL, 36% motile 5 weeks: 190 X 10 6/mL, 50% motile 5 weeks: 13 X 106 /mL, 8% motile 5 weeks: 18 X 106 /mL, 13% motile 4 weeks: 65 X 106 /mL, 45% motile 3 weeks: 184 X 10 6/mL, 55% motile

7 weeks: 1/20 HPF, 0% motile 10 weeks 1/5 HPF, 0% motile 7 weeks: 1/20 HPF, 0% motile 9 weeks: 30 X 10 6/mL, 40% motile 8 weeks: 13 X 10 6/mL, 48% motile 8 weeks: 5 X 10 6/mL, 30% motile 9 weeks: 15 X 106 /mL, 2% motile 9 weeks: 1/2 HPF, 1% motile 9 weeks: No sperm 6 weeks: No sperm

Vol. 59, No.2, February 1993

3rd assay

14 weeks: 1/3 HPF, 0% motile 14 weeks: 1/10 HPF, 0% motile 13 weeks: 3 X 106 /mL, 0% motile 18 weeks: 1/3 HPF, 0% motile 13 weeks: 1/20 HPF, 0% motile

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433

Of the men in this study who submitted the first specimen for testing more than 14 weeks after vasectomy' 19% had some residual nonmotile sperm. A previous study (9) showed that occasional nonmotile sperm could still be found in centrifuged specimens in 10% of men a year after successful vasectomy. If complete azoospermia is insisted on, such men become a problem, requiring repeated testing that is not always completed (2, 3, 5) or a "special clearance" (2-4, 6) and sometimes in earlier years one or more repeat vasectomies (3, 6). In the writer's experience none of these measures are necessary. The regimen now suggested is to test 4 weeks after vasectomy by examining specimens within 12 hours of collection, to repeat tests if any motile sperm are detected, and to give a clearance as to sterility if only nonmotile sperm are found. The regimen depends on accepting that nonmotile sperm will not generate pregnancies. This is not a foolhardy assumption. Nonmotile sperm, whether or not they are dead, cannot penetrate cervical mucus. Furthermore, vigorous beating of the sperm tail is necessary to penetrate and fertilize an ovum (10). There is thus a strong physiological foundation for basing the "all clear" on absence of motile sperm rather than on complete azoospermia. It is supported by clinical observation: pregnancies do not result as a consequence of nonmotile sperm in postvasectomy tests being disregarded (2-4, 6, 8, 9). In this series more than 1,000 men were given clearance when nonmotile sperm were still present, sometimes in large numbers. The single pregnancy in this group was the result of late recanalization, with reappearance of motile sperm. If sperm motility is critical, an acceptable time interval between collection and examination of specimens must be determined. For azoospermic specimens, the interval is unimportant, but for specimens containing sperm, a maximum interval of 12 hours is required. The theoretical basis for this is that with seminal fluid in vitro, at room temperature (23°C), it takes 12 hours for the percentage of motile sperm to be halved, with little change in their velocity (13). The best time to start testing after vasectomy is a matter of value judgement. Azoospermia is reached in most men after 10 ejaculations after vasectomy (14), although not invariably so. When specimens were requested after 10 ejaculations, some men submitted them within as many days after vasectomy, causing concern that this might be too soon for spontaneous recanalization to be detectable. After 434

Edwards Earlier testing after vasectomy

it had been shown (15) that the disappearance of motile sperm, as distinct from complete azoospermia, is not related to the number of ejaculations and usually occurs by the 15th day after vasectomy, the regimen was changed: a minimum time of 3 weeks was suggested, regardless of the number of ejaculations. It then became apparent that the sooner tests are done the sooner most men will be cleared but at the cost of more people needing to have tests repeated. Of those tested 3 weeks after vasectomy, about 5% still had motile sperm and thus needed repeat tests. The proportion fell to about 1 % if tests were done at 4 weeks. For this reason the suggested minimum time was finally changed from 3 weeks to 4 weeks after vasectomy, the time now recommended by the writer. Some writers have suggested (1) that starting tests sooner than 3 months after vasectomy carries the risk of failure to detect some cases of recanalization, which might not be apparent before then. Published data about this possibility is scanty: in one series (7), three cases of recanalization that were tested first at 2 months had motile sperm present at that time, but another apparently did not. It is necessary to weigh the possibility of not detecting some rare instances of recanalization against the benefit of earlier testing. Another consideration is that the technique used for vasectomy may influence not only the likelihood of recanalization but also the time after vasectomy at which it would be likely to occur (1). Other regimens may be more appropriate for techniques other than the one used in this series. One reason for repeating tests could be the chance of recanalization happening between the first and a repeat test. Again it is a matter of weighing this unlikely possibility against the disadvantage of repeated tests. In this series, a single test was accepted if no motile sperm were reported, and there has been no apparent reason to change this policy. The intensity of the search for sperms in each specimen again depends on value judgement. It is practicable to examine only approximately one drop of semen, and the number of fields for microscopic examination is chosen arbitrarily. Some laboratories centrifuge specimens if no sperm are seen. In this series, the routine of the laboratory was accepted regarding the number of fields examined, but as only motile sperm were of interest, the results of centrifuging were disregarded. Tests give most patients assurance of sterility but are primarily intended to detect vasectomy failures. They are ineffective in this if men do not submit Fertility and Sterility

specimens. That 29% of patients in this series submitted no specimens is cause for considering whether the requirements may be difficult to comply with. The proportion compares favorably, however, with a recent American series of 1,029 (3) men, of whom 36% had no postvasectomy tests and only 54% completed the requirements of azoospermia in two specimens. In a Canadian series of 8,879 (2), only 59% completed testing. In a series reported from Scotland where the requirement was for specimens to be returned by mail in a prepaid envelope (5), 95 % of 284 men returned one specimen, but a request for repeat specimens reduced the number completing testing to 85%. Because other reports of routine postvasectomy testing do not give details of sperm motility, it has not been possible to compare the results reported here with those of others. Conspicuously lacking in the literature are data relating to how soon the presence of motile sperm can be expected to reveal the occurrence of spontaneous recanalization. Comparison of failure rates must be made with some reservations. Because vasectomy has low failure rates, <1 % in most reported studies (16), for one technique to be compared with another, data from a very large series must be collected before statistically significant differences become apparent. A failure rate of 1 in 4,000 is not significantly different from 3 in 4,000 (12). Moreover, operative failures need to be distinguished from spontaneous recanalization, which in turn should be classified as early or late (7). The total failure rate in this series was 5 in 3,178 (0.16%). One resulted from an inadequately performed vasectomy. The others were apparently caused by spontaneous recanalization (0.13%). Although lower than in many reported series, these rates are greater than that achieved by others who have used the vas sheath to cover one ofthe divided ends. Schmidt (17), in a series of 5,000, and Yeates (18), in a series of 1,500, both reported failure rates of 0%, whereas Errey and Edwards (12) reported 4 failures in 8,197 (0.05%). A possible reason for a higher rate of recanalization could have been an unintentional modification of Schmidt's technique: the sheath was closed using plain catgut rather than a nonabsorbable material as used by the aforementioned writers. Open -ended vasectomy does not necessarily affect the failure rate (12). Recanalization rates appear to be greater if the technique used does not include using the sheath to cover one end of vas: in a recently reported series of 16,796 vasectomies performed in this way by various surgeons (6), the early recanaVol. 59, No.2, February 1993

lization rate was 0.36%. The overall failure rate was 0.43%, the rate being influenced by the experience of the surgeon but not by whether the vas was ligated or cauterized. Testing cannot detect all failures: late spontaneous recanalization can occur, even after the most rigorous testing has demonstrated that sterility has been achieved after the vasectomy (2, 6, 7, 19,20). Estimated rates are very low: 6 in 14,000 (19) and 4 in 5,000 (20). This deficiency of the testing process may be more acceptable if viewed in the context of female sterilization, for which there is no practicable means of testing for spontaneous recanalization. It is not suggested that the regimen reported here will be suitable for all communities. On a global scale, it is unlikely that anyone testing regimen or any vasectomy technique will be ideal. It is clear from the reluctance of many patients to submit specimens that complete reliability is not every individual's foremost priority. The same may apply to communities. It could be that in some circumstances the cost benefit might not justify thousands of tests to detect an occasional failure. On the other hand, testing does detect operative failures, of which the inexperienced may not otherwise be aware. Also, unless tests are done and reported for large series of vasectomies, it is impossible to assess properly the supposed benefits of various techniques. For example, recently developed techniques for vasectomy (21) greatly reduce operating time but might prove to have increased failure rates. There is thus a continuing need for the collection and publication of the results of postvasectomy testing. Series must be large if the results are to be statistically significant when compared with others. The tests must include observation of sperm motility if cases of vasectomy failure are to be distinguished from mere persistence of nonmotile sperm. Acknowledgment. I thank Alan E. Stark, Ph.D., of The School of Community Medicine, The University of New South Wales, for his invaluable advice and statistical calculations.

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