Dear Editor

In reply to the points raised by Cunningham et al.[1] to the British Andrology Society post vasectomy guidelines, we feel that the authors answer their own criticism - especially the need to assess fresh samples if sperm are found in the initial sample. Our guidelines are to allow the identification of men with few motile cells following heavy criticism from our own referees.

24 hour old azoospermic samples, whilst unpleasant give you the same answer and we clearly say that patient compliance is more important than time to examination - i.e. an aged sample is better than no sample. We recommend positive displacement pipettes & phase contrast microscopy as these are normally found in laboratories that provide high quality andrological services. The highly viscous nature of semen can mean that a positive displacement pipetteis the only way to actually remove a complete pellet. Phase contrast also offers benefits over standard bright- field illumination as a more rapid medium for screening semen samples. The other point raised concerned unexpected pregnancies. In our guidelines we did state this was a difficult area to quantify, as if pregnancies did occur we do not know how many women would seek termination rather than the potential trauma associated with pregnancy following a supposedly sucessful vasectomy.

Our guidelines are best practice, and we feel that in this increasingly litigatious society this is what is required. If workers want to take the risk of missing someone with a failed vasectomy by not following them then that is a choice they make, but it may have to be justified in court. We can only give best practice and leave it to their judgement.

References

(1) Richard Cunningham, David Dance, Jim Greig, and Adam Brown. Assessment of post vasectomy semen samples [electronic response to P Hancock and E McLaughlin. British Andrology Society guidelines for the assessment of post vasectomy semen samples (2002)] jclinpath.com 2003 http://jcp.bmjjournals.com/cgi/eletters/55/11/812#14

Dear Editor

We read with interest the British Andrology Society (BAS) guidelines for the assessment of post vasectomy semen samples (2002).[1] The authors have carried out a thorough and comprehensive review of the topic, and we are convinced by their recommendation that assessment should be undertaken 16 weeks and at least 24 ejaculates after vasectomy. We are unconvinced however, by the specific recommendations about sample collection, transport and examination. First, no evidence is provided to support the need for samples to be maintained at body temperature, delivered to the laboratory within one hour, and examined within four hours. Since the presence of any spermatozoa in the sample indicates a need for further samples, assessment of motility and morphology is not essential. Secondly, the recommendations for the use of a direct displacement pipette, centrifugation of samples negative on direct microscopy and quantitation of spermatozoa are excessive and potentially costly, and appear to have been taken directly from methods used appropriately in assessment of infertility. We would question the need for such sensitive methods in determining whether or not a vasectomy has been successful. The majority of patients undergoing vasectomy will have been previously fully fertile, with sperm counts ³106/ml. The success of the operation can be judged on the basis of the disappearance of sperms based on a simpler assessment of sperm count. For many years our method for assessment of post-vasectomy semen samples has involved requesting samples at 10 and 12 weeks after 5 days of abstinence. Samples are delivered on the day of collection via the routine GP transport services and examined at the end of each working day. We examine each specimen by direct light microscopy using an x40 objective. One drop of uncentrifuged sample is transferred to a slide using a disposable Pasteur pipette for each sample. The presence of motile and non-motile spermatozoa in one scan across the slide is reported semi-quantitatively (+, ++, or +++. Samples are repeated until 2 consecutive negative samples have been reported. 4542 patients have been assessed by this method between 1997 and 2002. We are not aware of any unexpected pregnancies after reporting patients negative by our method, excluding a small number clearly due to late recanalisation. The surgeons or GPs who carried out vasectomies on 1781 of these patients were contacted, again they were unaware of any unexpected pregnancies. We estimate that with a median frequency of sexual intercourse of 4 in 4 weeks in males aged between 25 and 44 years,2 that there are likely to have been over 3.5 million episodes of sexual intercourse in our cohort over the last 5 years. These results support our contention that more elaborate methods of semen analysis are not necessary. Our results are consistent with those of Haldar et al who reviewed over 30,000 vasectomies assessed without centrifugation and did not report any pregnancies which were not attributable to late recanalisation.3 Guidelines from learned societies are always welcome, but must take into account the opportunity costs of unnecessarily rigorous laboratory methods. It is easy to suggest a more complex way of processing any pathology specimen, but far more difficult to define the most cost- effective method, while still maintaining high levels of sensitivity and specificity.

References

(1) British Andrology Society. British Andrology Society guidelines for the assessment of post vasectomy semen samples (2002). J Clin Pathol 2002;55:812-816.

(2) Johnson AM et al. Sexual behaviour in Britain:partnerships, practices, and HIV risk behaviours. Lancet 2001;358:1835-42.

(3) Haldar N, Cranston D, Turner E, MacKenzie I, Guillebaud J. How reliable is a vasectomy? Longterm follow-up of vasectomised men. Lancet 2000;356:43-44.