2016 Laboratory guidelines for postvasectomy semen analysis: Association of Biomedical Andrologists, the British Andrology Society and the British Association of Urological Surgeons
TL;DR: These 2016 guidelines replace the 2002 British Andrology Society laboratory guidelines and should be regarded as definitive for the UK in the provision of a quality PVSA service, accredited to ISO 15189:2012, as overseen by the United Kingdom Accreditation Service (UKAS).
Abstract: Post-vasectomy semen analysis (PVSA) is the procedure used to establish whether sperm are present in the semen following a vasectomy. PVSA is presently carried out by a wide variety of individuals, ranging from doctors and nurses in general practitioner (GP) surgeries to specialist scientists in andrology laboratories, with highly variable results.Key recommendations are that: (1) PVSA should take place a minimum of 12 weeks after surgery and after a minimum of 20 ejaculations. (2) Laboratories should routinely examine samples within 4 h of production if assessing for the presence of sperm. If non-motile sperm are observed, further samples must be examined within 1 h of production. (3) Assessment of a single sample is acceptable to confirm vasectomy success if all recommendations and laboratory methodology are met and no sperm are observed. Clearance can then be given. (4) The level for special clearance should be <100 000/mL non-motile sperm. Special clearance cannot be provided if any motile sperm are observed and should only be given after assessment of two samples in full accordance with the methods contained within these guidelines. Surgeons are responsible both preoperatively and postoperatively for the counselling of patients and their partners regarding complications and the possibility of late recanalisation after clearance. These 2016 guidelines replace the 2002 British Andrology Society (BAS) laboratory guidelines and should be regarded as definitive for the UK in the provision of a quality PVSA service, accredited to ISO 15189:2012, as overseen by the United Kingdom Accreditation Service (UKAS).
Summary (4 min read)
- Post vasectomy semen analysis (PVSA) is the laboratory procedure used to establish whether sperm are present in the semen following a vasectomy.
- This ranges from doctors and nurses in GP surgeries to specialist scientists in dedicated andrology laboratories.
- In 2002 the British Andrology Society (BAS) published a set of laboratory guidelines for PVSA .
- Revisions include clarifying factors around when and how to test and the number of samples that should be examined.
- Measurements of vasectomy failure are complex to interpret, as many are only discovered after an adverse outcome, i.e. occurrence of a pregnancy.
FERTILITY OF RESIDUAL SPERM POST SURGERY
- Ejaculates may contain potentially fertile sperm immediately after vasectomy , and patients should continue with contraceptive precautions until successful vasectomy has been confirmed.
- This has been extensively discussed in the 2002 BAS guidelines  and by the FSRH .
Scheduling of sample testing
- The time between the vasectomy and the PVSA has been widely discussed without agreement, with some publications even suggesting a wait of up to 6 months before first analysis .
- This may be due to an inflammatory reaction and/or temporary bruising within the testis.
- Testing too early may also cause problems with analysis due to high sample viscosity, presence of residual (usually non-motile) sperm and raised levels of round cells that may mask sperm presence.
- Therefore, the desire to perform prematurely early PVSAs has to be balanced against the increased patient inconvenience and also the workload / cost to the laboratory (e.g. [16 17 22 23]) as repeat tests would be required for accurate confirmatory diagnosis.
- It has also been reported that azoospermia may not be achieved until 60 ejaculates for some individuals .
- The laboratory staff should ensure that the person requesting the PVSA test is provided with clear ‘user information’ in the form of written instructions for sample collection.
- Sample production should be arranged on an appointment basis to ensure the laboratory has sufficient time for each assessment to be completed within recommended analytical time frames.
The specimen container
- Gamma-irradiated and mouse embryo assay (MEA)-tested specimen containers are recommended for use, together with CE-marking for containers manufactured in Europe.
- None of these tests confirm the level of sperm non-toxicity.
- Specimen containers should therefore additionally be confirmed as non-toxic to sperm via an in-house sperm toxicity bioassay .
- If samples are provided in unscreened specimen containers, the PVSA report will only be valid if no sperm are observed.
- If sperm are observed, and they are immotile, then no confirmation of sperm non-toxicity from the 2016 PVSA Guidelines specimen container can be provided.
Instructions to patients
- Patients should be advised to produce a sample in accordance with guidelines for good practice e.g.  29.
- The abstinence period should be between 2 and 7 days as per the latest WHO guidance .
- Men should be asked to collect their entire ejaculate by masturbation.
- Use of coitus interruptus, condoms or oral production is not recommended as this can lead to sample contamination.
- One study reported that 9.4% PVSA samples were not completely collected , which could increase the risk of misdiagnosis if analysed.
Receipt of Samples
- On delivery of the semen sample to the laboratory reception, staff should ensure that the specimen container is clearly labelled with at least three patient identifiers (e.g. name, date of birth, and clinic number) and that details of sample collection are recorded, e.g. abstinence period and confirmation that the entire sample was collected.
- All staff dealing with patient contact should be trained appropriately in respecting privacy and dignity.
- Associated facilities and systems for the service should also ensure that this is recognised as an important part of diagnostic provision.
Overall Guidance on Sample Procurement
- To prevent time delays or fluctuations in temperature, on-site production facilities are recommended.
- If non-motile sperm are observed, further samples must be examined within 1 hour of production.
- If samples are over 4 hours old as stated above, there is currently insufficient data to validate the accuracy of any results obtained, particularly with relation to uncontrolled transport situations.
- Laboratories accepting posted/couriered samples should ensure that patients understand the sample/request form labelling requirements and the current regulations for the transport and packaging of samples.
- Where examination of a sample occurs outside recommended parameters this must be clearly noted on the report and clearance should not be given, also known as Recommendation 2b.
- Due to the viscous nature of semen samples, a positive displacement pipette (PDP) should be used for all aliquot sampling.
- A phase contrast microscope, with x200 and x400 magnification, is required.
- A centrifuge that can take 15ml tubes is recommended, with a rotor that has been calibrated to provide a 3000g force for 15 minutes as per the original BAS 2002 guidelines.
- This is the maximum speed recommended by WHO for the assessment of azoospermia as higher speeds may risk damage to the sperm, such as decapitation, which makes their detection less likely .
- The centrifuge should be calibrated to metrologically accepted standard, in accordance with ISO 15189:2012.
- Samples should ideally be examined once liquefaction is complete, accepting that this may not be possible, since PVSA samples may continue to be highly viscous.
- Two methods of examination are possible: 1. The original 2002 BAS guidelines method.
- The entire pellet should be resuspended in a minimum volume of autologous seminal plasma (< 100μl) and the entire sample examined systematically for the presence of motile and non-motile sperm.
- Microscopic examination of uncentrifuged specimens has been shown to be a reliable method for PVSA, provided >100,000 sperm per ml are present .
- If the 100µm large volume fixed depth slide method is not used, it is the consensus view of the Professional Bodies that samples should be centrifuged.
INTERNAL QUALITY CONTROL
- In order to ensure precise and accurate results from the PVSA testing laboratory, a process of internal quality control (IQC) is required.
- Day-to-day monitoring of precision and accuracy reassures users of the service that there is uniformity within the laboratory.
- IQC requires a central reference sample to enable direct comparisons between different laboratory staff performing PVSA.
- An EQA scheme for PVSA should provide independent consensus for the presence/absence of sperm.
- The impracticality of providing such EQA, which should involve sending out sperm-free samples and samples with a very low numbers of sperm, has deterred other schemes being set-up nationally or internationally to date.
POST ASSESSMENT - THE UNCERTAINTY FACTOR
- There are many areas where uncertainty can lead to questions about the robustness of PVSA.
- The recommendations in these guidelines aim to reduce the uncertainty.
- Unless strict sample rejection criteria are enforced, a higher than necessary uncertainty will impact on the PVSA.
- It has been reported that a large proportion of patients (up to 25%) fail to comply with instructions regarding sample collection, making reliable laboratory assessment impossible, or fail to submit a sample in the first place[16 39 40].
- Such volumes should be included and highlighted in the final report to draw attention to this possible uncertainty.
HOW MANY SAMPLES SHOULD BE ASSESSED?
- The 2002 BAS guidelines recommended examination of two samples per patient to ensure correct evaluation.
- After assessing the supporting evidence, the Professional Bodies agree that assessment of a single sample is appropriate provided there is strict adherence to instructions for production, delivery and time to examination, to minimise any adverse effects on the sample.
- Similarly, sperm have been reported to temporarily reappear in ejaculates 12 months after surgery, despite previous sperm-free ejaculates.
- Discussion in the literature has suggested that the risk of pregnancy occurring from men whose previous samples show non-motile sperm present is small and probably no more than the risk of pregnancy after two azoospermic semen samples, as a result of spontaneous recanalisation [3 45].
- Laboratories must be able to validate & verify that their reported counts are accurate and what their detection accuracy or range may be, accepting there will be a measure of uncertainty.
CONCLUSIONS & IMPLEMENTATION
- The Professional Bodies expect that implementation of these guidelines can occur from the date of publication and should be completed within 12 months.
- The first semen analysis after vasectomy: timing and definition of success.
- Tomlinson MJ, Harbottle SJ, Woodward BJ, Lindsay KS, Association of Biomedical A. Association of biomedical andrologists - laboratory andrology guidelines for good practice version 3 - 2012.
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Cites background from "2016 Laboratory guidelines for post..."
...The MEL should not exceed 4-h, since this represents the maximum recommended delivery time that may be used for a post vasectomy sample ....
Cites background from "2016 Laboratory guidelines for post..."
...In recent guidelines issued conjointly by the British Andrology Society and the British Association of Urological Surgeons, assessment of one semen specimen preferably examined within 1 hour of the collection in a laboratory that uses proper methods- is enough to confirm sterility if no sperm are seen (14)....
"2016 Laboratory guidelines for post..." refers background in this paper
...It is always important for patients to be warned that a vasectomy may apparently fail at any time, though the actual chance of this is rare, at less than 1% if correctly performed [3-8], with some reports suggesting that temporary reappearance of sperm may occur a year after clear PVSA ....
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