Human Reproduction, Vol. 14, No. 7, 1823-1826,
July 1999
© 1999 European Society of Human Reproduction and Embryology
British Andrology Society guidelines for the screening of semen donors for donor insemination (1999)
c/o Dr Eileen A McLaughlin, Chairman, University Division of Obstetrics & Gynaecology, St Michael's Hospital, Bristol, BS2 8EG, UK
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Abstract |
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The British Andrology Society (BAS) guidelines for the screening of semen donors have undergone a recent review, and following consultation with members of the Society and with experts in the allied professions, the following revised guidelines have been issued. Major changes include the introduction of an upper age limit for semen donors (<40 years old) and the general exclusion of men who are seropositive for cytomegalovirus as donors. The BAS recommends the screening of prospective semen donors for chromosomal abnormalities and for cystic fibrosis carrier status. Following the report of cross-contamination of human cells with hepatitis B virus within a liquid nitrogen storage vessel, the BAS recommends that steps be taken to ensure the safe cryopreservation of donor gametes.
Key words: artificial insemination/BAS guidelines/donor/semen
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Aims |
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The aims of the British Andrology Society (BAS) guidelines for the recruitment and screening of semen donors are the protection of recipients and offspring from infection and the protection of offspring from inheritable disorder. These guidelines do not address the counselling of semen donors and recipients or discuss the indications for donor insemination, all of which are dealt with in the Human Fertilisation and Embryology Authority Code of Practice (HFEA, 1998
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Recruitment |
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As attempts within the UK to recruit altruistic men of proven fertility have been largely unsuccessful it is recommended that centres do not exclude men of unproven fertility from donating semen and that centres continue to make reasonable compensatory payments to donors (HFEA, 1998;
McLaughlin et al., 1998). |
Clinical assessment |
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Semen donors should be generally healthy and <40 years of age at the time of donation. All donors prior to acceptance should be interviewed and examined by a medical doctor. Assessment should cover basic personal data, current general health, past medical and surgical history, family history (including a detailed genetic history), occupational and social history, medical and illicit drug use, reproductive and sexual history (HFEA, 1998
). Particular attention should be paid to exclude donors at risk of transmitting infection or genetic disease.
Sexual history
Donors with a history of sexually transmitted viral disease such as hepatitis B, genital warts or herpes must be rejected. A distant past history of bacterial sexually transmitted disease (STD) is not an exclusion criterion as long as the donor is shown to be negative at the time of donation and adequate treatment has been proven to be given. Prospective donors with evidence of risk behaviour, such as a recent episode of bacterial STD or unprotected sexual intercourse with multiple partners should be rejected.
Physical examination
Donors should undergo a general physical examination by an appropriately trained clinician, to detect STD (e.g. urethral discharge, genital warts and genital ulcers), inherited congenital abnormalities (e.g. hypospadias) and evidence of high-risk behaviour (e.g. intravenous drug abuse) (Barratt and Cooke, 1989; Barratt et al., 1990). A donor with physical findings of infection, genetic disease or risk behaviour should be rejected.
Screening tests for sexually transmitted disease
Prospective donors should be screened for the presence of human immunodeficiency virus (HIV) 1 and 2 antibody; hepatitis B surface antigen (HbsAg); hepatitis C (HVC) antibodies; and syphilis using the appropriate serological tests.
Screening should also be undertaken using enzyme-linked immunosorbent assay (ELISA) or direct culture of urethral swabs (Robinson, 1998), or by the use of molecular tests on a first catch urine (Taylor-Robinson, 1997) for Neisseria gonorrhoea and Chlamydia trachomatis. If any of the above tests are positive the donor must be rejected and offered appropriate counselling and treatment.
Screening for cytomegalovirus (CMV) antibodies
Prospective donors should be screened for CMV antibodies (IgG and IgM) [American Society for Reproductive Medicine (ASRM), 1998]. Maternal CMV infection may have serious repercussions as congenital disease occurs in up to 40% of women who have a primary CMV infection in pregnancy (Raynor, 1993; Hemmings et al., 1998). Of those infants infected, 18% will be symptomatic at birth and as many as 13% of infants born to mothers primarily infected with CMV during pregnancy will have mental retardation and 8% bilateral hearing loss (Fowler et al., 1992).
As all seropositive individuals harbour CMV DNA (Larsson et al., 1998), all prospective donors should be screened for the presence of CMV (IgG and IgM) antibodies using the appropriate serological test. Though risks to offspring via donor insemination remain unquantifiable, CMV has been identified in human semen (Mansat et al., 1997) and the BAS recommends that only semen from seronegative donors be stored for clinical use.
In a small minority of cases, clinics may be unable to recruit a seronegative donor when the donor belongs to a particular ethnic group with a high incidence of seropositive individuals. The decision to treat a patient with a seropositive donor should be a matter of clinical judgement. In these exceptional circumstances it would be possible to use semen from seropositive men for recipients who are also CMV seropositive. Semen from seropositive donors must only be used where the donor is IgG positive and IgM negative (ASRM, 1998) indicating that the donor is unlikely to have an active infection. Centres should be aware that CMV recurrence in a previously infected woman is more likely if she is multiply-exposed to CMV by sexual activity prior to pregnancy (Shen et al., 1993). Thus congenital infection following insemination with semen from a seropositive donor, even if unlikely (Liesnard et al., 1998), cannot be ruled out. Semen from a donor who is initially seronegative and seroconverts whilst donating must not be used for treatment purposes.
Screening tests for fertility
A seminal analysis, using current World Health Organization protocols (WHO, 1999), should be performed on all samples prior to cryopreservation. The donor should have normal seminal characteristics according to local reference ranges. Post-thaw cryosurvival rates must be assessed and clinics should only store ejaculates meeting local quality assurance standards.
If sperm function tests are available, such as quantitative sperm motility measurements, acrosome reaction challenge test, hamster egg test, and zona binding assays, they are of additional value in predicting the fertilizing potential of the semen (Irvine and Aitken, 1986; Holt et al., 1989; Tesarik, 1989; Oehninger et al., 1992; Macleod and Irvine, 1995).
Genetic history
In addition, a full family medical and genetic history should be taken and those donors identified as at risk of transmitting an inherited disorder should be rejected (American Association of Tissue Banks, 1996;ASRM, 1998). As a minimum, genetic screening for semen donors and their families should include the following.
The donor:
- (i) should not have (had) any familial disease with a major genetic component such as cleft lip, cleft palate, spina bifida, congenital heart malformation, congenital hip dislocation, clubfoot, hypospadias. These have a chance of up to 5% of occurring in an offspring of an affected man.
(ii) should not have (had) any non-trivial Mendelian disorder, such as albinism (general or ocular), haemophilia, haemoglobin disorder, hereditary hypercholesterolaemia, neurofibromatosis, or tuberous sclerosis. A trivial malformation is defined as one that has no adverse effect on the bearer.
(iii) should not have (had) any familial disease with a known or reliably indicated major genetic component, such as asthma (restricted to its more florid forms and persisting into adulthood), juvenile diabetes mellitus, epileptic disorder, severe hypertension, a psychosis, rheumatoid arthritis, or a severe refractive disorder.
(iv) should not be heterozygous for an autosomal recessive gene known to be prevalent in the donor's ethnic background, for which heterozygosity can be detected. This includes cystic fibrosis in Caucasian populations, ß-thalassaemia in Mediterranean populations, sickle-cell disease in African and Afro-Caribbean populations, and Tay–Sachs and Gaucher's disease in Jews of Eastern European descent and certain other population isolates.
(v) should not carry a chromosomal rearrangement that may result in unbalanced gametes.
(vi) should be <40 years old.
Advanced paternal age is associated with new mutations in the paternal genome (Fletcher and Marsden, 1996; Moloney et al., 1996; Crow, 1997; Tolarova et al., 1997; Tellier et al., 1998) and an increased risk of aneuploidy in the fetus (Thepot et al., 1993; Griffin et al., 1995; Griffin, 1996; Thepot et al., 1996; Wyrobek et al., 1996). This age limit is compatible with the recommendations of the American Association of Tissue Banks Standards for Semen Banking (AATB, 1996; Linden and Centola, 1997) and the French CECOS Federation (Lansac et al., 1997).
On the basis of a family history, the donor's first-degree relatives (parents, siblings or offspring) should be free of:
- (i) major malformations as in (i) above;
- (a) autosomal dominant or X-linked with age of onset extending beyond the age of the donor, such as Huntington's disease;
- (b) autosomal dominant inheritance with reduced penetrance, such as Marfan syndrome and Alport's disease;
- (c) autosomal recessive inheritance, particularly if the disease has a high frequency in the population, as for example cystic fibrosis; and
(ii) non-trivial disorders, showing Mendelian inheritance in the following categories:
(iii) a chromosomal abnormality unless the donor has a normal karyotype.
Screening tests for genetic disease
Karyotyping
It is recommended that potential semen donors should be screened for chromosomal abnormalities. The likelihood of a healthy male having a chromosomal problem that could be damaging to offspring is small. The frequency of balanced translocations is <2 per 1000 (Evans et al., 1978), but recent studies have shown that previously unsuspected cytogenetic abnormalities may be detected during routine screening of oocyte (Wallerstein et al., 1998) and semen donors (Bick et al., 1998).
Autosomal recessive conditions
It is recommended that potential semen donors should be screened for autosomal recessive gene(s) known to be prevalent in the donor's ethnic background for which carrier status can be detected, e.g. cystic fibrosis (CF), ß-thalassaemia, sickle-cell disease and Tay–Sachs disease. As the incidence and distribution of mutant alleles among CF carriers varies according to the population studied (Brock et al., 1998), any CF screening undertaken should be appropriate to the individual donor (Asch et al., 1998).
Where centres decide to implement such screening, it is mandatory that adequate pre-test information and counselling is provided, and that centres are able to provide appropriate advice and support to donors who test positive (HFEA, 1998). A donor found to have a significant chromosomal abnormality should be rejected. The decision to reject a prospective donor who is a carrier of a recessive condition should be a matter of clinical judgement.
Rhesus incompatibility
Rhesus blood grouping should be undertaken. If the use of donor spermatozoa creates the potential of a rhesus incompatibility, recipients should be informed regarding the obstetric significance of this condition.
Sample collection and storage
If all screening tests for STD and genetic disease are negative and post-thaw survival rates acceptable, semen samples may be collected and cryopreserved. All ejaculates must have post-thaw cryosurvival rates assessed and clinics should aim to store sufficient straws meeting local quality assurance standards, for the appropriate number of desired offspring, i.e. maximum 10 live births plus siblings (HFEA, 1998).
Following the report of cross-contamination of human cells with hepatitis B virus within a liquid nitrogen storage vessel (Tedder et al., 1995), it is recommended that straws and ampoules containing gametes should be sealed and free from external contamination. Ejaculates from unscreened individuals should not be stored in the same liquid nitrogen vessel as semen from donors who have been screened and found negative.
It is also recommended that liquid nitrogen storage vessels and cooling machines should be subject to regular disinfection and that care should be taken to avoid contamination of storage vessels and cooling machines with environmental organisms (Fountain et al., 1997).
As the safety and efficacy of secondary containment (Russell et al., 1997) and gaseous phase storage systems for gametes remains unproven, the BAS recommends that clinics await the evaluation of new packaging and storage systems before implementation in routine clinical practice (Avery et al., 1998).
Quarantining
Donors should be re-tested at regular intervals (at least every 6 months) for sexually transmitted disease. Screening must include HIV 1 and 2 antibody, HbsAg, HVC antibodies, syphilis and CMV antibodies using the appropriate serological tests. Repeat screening should be performed for Neisseria gonorrhoea and Chlamydia trachomatis and donors should undergo a repeat physical examination to exclude bacterial and viral STD.
All screening tests must be negative prior to the release of semen for clinical use. Only ejaculates which have been in storage for >180 days at the time of re-testing are suitable for clinical use (HFEA, 1998).
Ejaculates from a donor who has contracted a STD should not be released for clinical use and should be removed from central storage. The decision to use semen samples from other donors, which have been stored with infected material, should be a matter of clinical judgement.
Surveillance
Serum from all donors should be collected and stored in the event that a currently unidentified viral or bacterial pathogen should become detectable in the future. The method of informing a donor of his (past) infected status should be a matter of clinical judgement.
The outcome of donor pregnancies should be followed closely with particular reference to the birth of abnormal offspring. Donors found to be carrying previously unsuspected genetic diseases should be withdrawn from clinical use. The decision to inform a donor of his carrier status should be a matter of clinical judgement.
Clinics should be aware that transmission of infection or genetic disease via screened donor semen (though minimal) remains possible and the BAS recommends that centres advise recipients of the risks (HFEA, 1998).
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Revision of guidelines |
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TopAbstractAimsRecruitmentClinical assessmentRevision of guidelinesReferences |
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It is the intention of the BAS committee that these guidelines will be reviewed on a regular basis and updated as necessary.
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Acknowledgments |
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The BAS thanks Dr Peter Lunt, Consultant Clinical Geneticist, University of Bristol Division of Child Heath and Dr Ann Dalton, Senior Clinical Scientist, South Trent Molecular Genetics Service, for their help and advice.
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References |
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TopAbstractAimsRecruitmentClinical assessmentRevision of guidelinesReferences |
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Submitted on January 20, 1999; accepted on March 26, 1999.
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