RESUMO
Preimplantation genetic testing (PGT) is the earliest form of prenatal diagnosis that has become an established procedure for couples at risk of passing a severe genetic disease to their offspring. At UMC Ljubljana, we conducted a retrospective register-based study to present 15 years of PGT service within the public healthcare system in Slovenia. We collected the data of the PGT cycles from 2004 to 2019 and compared clinical outcomes for chromosomal and monogenic diseases using different embryo biopsy and testing approaches. In addition, we assessed the extent to which PGT has become the preferred option compared to classic prenatal diagnostics. We treated 211 couples, 110 with single gene disorder, 88 with structural chromosome rearrangement and 13 for numerical chromosome aberration. There were 375 PGT cycles with oocyte retrieval, while embryo transfer was possible in 263 cases resulting in 78 deliveries and 84 children. Altogether, the clinical pregnancy rate per embryo transfer was 31% in 2004-2016 (blastomere biopsy) and 43% in 2017-19 (blastocyst biopsy), respectively. We assessed that approximately a third of couples would opt for PGT, while the rest preferred natural conception with prenatal diagnosis. Our results show that providing a PGT service within the public healthcare system has become a considerable option in pregnancy planning for couples at risk of transmitting a severe genetic disease to their offspring. In Slovenia, approximately a third of couples would opt for PGT. Although the number of cycles is small, our clinical results are comparable to larger centres.
RESUMO
Ovarian cancer is among the most common gynecologic cancers and unfortunately the most common cause of death from gynecologic malignancies. Due to few early symptoms and insufficient screening programs, an early diagnosis of ovarian cancer is very difficult and new biomarkers related to early ovarian carcinogenesis are needed. In the last years a growing scientific knowledge about cancer stem cells and their markers opened a new perspective on screening and early diagnosis of ovarian cancer. The transcription factor NANOG is not only a pluripotency and cancer stem cell-related marker, but also promotes cancer stem cell-like characteristics of tumor, tumor growth, dissemination, immune evasion, and resistance to conventional therapy. The recent data showed that small stem cells resembling very small embryonic-like stem cells are present in the ovarian surface epithelium of adult human ovaries. These cells expressed several genes related to primordial germ cells, germinal lineage, and pluripotency, including NANOG, therefore their involvement in the manifestation of ovarian cancer are not excluded. As majority of cancer cells within a tumor are non tumorigenic, the therapies targeting these cells cause tumor regression, but the survived cancer stem cells regenerate the tumor, so tumor relapse or reoccur. The eradication of cancer actually requires the elimination of cancer stem cells, therefore new strategies in treatment that specifically target cancer stem cells are urgently needed. Although the therapeutic efficacy of targeting NANOG as a cancer treatment method is still in experimental phase, the gene therapy with small interfering RNA or short hairpin RNA have already shown some promising therapeutic potential. The authors can conclude that NANOG represents a promising diagnostic marker and agent for target therapy of ovarian cancer.
Assuntos
Proteína Homeobox Nanog/análise , Células-Tronco Neoplásicas/química , Neoplasias Ovarianas/diagnóstico , Células-Tronco Pluripotentes/química , Biomarcadores Tumorais/análise , Resistencia a Medicamentos Antineoplásicos , Feminino , Terapia Genética , Humanos , Proteína Homeobox Nanog/antagonistas & inibidores , Proteína Homeobox Nanog/fisiologia , Neoplasias Ovarianas/patologia , Neoplasias Ovarianas/terapiaRESUMO
A retrospective matched-control study to evaluate the effect of uterine anomalies on pregnancy rates after 2481 embryo transfers in conventionally stimulated IVF/intracytoplasmic sperm injection (ICSI) cycles. The study group of 289 embryo transfers before and 538 embryo transfers following hysteroscopic resection of a uterine septum was compared with two consecutive embryo transfers in the control group. Groups were matched for age, body mass index, ovarian stimulation, embryo quality, IVF or ICSI and infertility aetiologies. Number of embryos transferred, embryo quality and absence of uterine anomalies significantly predicted the pregnancy rates in the study group: odds ratios (OR) 1.7, 2.6 and 2.5, respectively (P<0.001). Pregnancy rates after embryo transfer before hysteroscopic metroplasty were significantly lower, both in women with subseptate and septate uterus and in women with arcuate uterus compared with controls. If two or three embryos with at least one best-quality embryo were transferred, the differences were 9.6% versus 43.6%, OR 7.3 (P<0.001) and 20.9% versus 35.5%, OR 2.1 (P<0.03), respectively. Differences in terms of live birth rates were even more evident: 1.9% versus 38.6%, OR 32 (P<0.001) and 3.0% versus 30.4%, OR 14 (P<0.001). After surgery, the differences disappeared. This retrospective matched control study evaluated the influence of septate, subseptate and arcuate uterus on pregnancy and live birth rates after 2481 in conventionally stimulated IVF/intracytoplasmic sperm injection (ICSI) cycles. The study group included 827 embryo transfers (289 embryo transfers before and 538 embryo transfers following hysteroscopic resection of uterine septum ans was compared with two consecutive mebryo transfers in the control group. Both groups were matched by age, body mass index, stimulation protocol, quality of embryos, use of IVF or ICSI, and infertility aetiologies. Multivariate logistic regression analysis of the study group showed that the number of embryos, embryo quality and the absence of uterine anomalies significantly predicted the pregnancy rates: odds ratios (OR) 1.7, 2.6, and 2.5, respectively (P<0.001). The pregnancy and live birth rates before surgery were lower compared with controls, both in women with subseptate or septate uterus and in women with arcuate uterus. If two or three embryos with at least one best quality embryo were transferred, the differences in terms of pregnancy rates were 9.6% versus 43.6%, OR=7.3 (P<0.001) and 20.9% versus 35.5%, OR=2.1 (P<0.03), respectively. The differences in terms of live birth rates were even more evident: 1.9% versus 38.6%, OR=32 (P<0.001) and 3.0% versus 30.4%, OR=14 (P<0.001). After surgery, the differences disappeared. Negative impact of uterine anomalies on pregnancy and on live birth rates are two important arguments for treating uterine anomalies in infertile women.
Assuntos
Infertilidade Feminina/cirurgia , Nascido Vivo , Taxa de Gravidez , Útero/anormalidades , Aborto Espontâneo/epidemiologia , Adulto , Estudos de Casos e Controles , Transferência Embrionária/estatística & dados numéricos , Feminino , Fertilização in vitro , Humanos , Histeroscopia , Infertilidade Feminina/epidemiologia , Gravidez , Estudos Retrospectivos , Eslovênia/epidemiologia , Injeções de Esperma Intracitoplásmicas , Útero/cirurgiaRESUMO
This is the first study evaluating whether oocyte development and fertilization competence are related to intrafollicular concentration of cholesterol, meiosis-activating sterols and progesterone, after human chorionic gonadotrophin (HCG) administration of women with polycystic ovarian syndrome (PCOS). The concentration of follicular fluid meiosis-activating sterol (FF-MAS) significantly increased in the periovulatory period from 10-14 to 34-38 h after HCG administration, while the concentration of testis meiosis-activating sterol (T-MAS) decreased, suggesting a HCG-dependent inhibition of sterol Delta14-reductase. There was no correlation between follicular lanosterol, FF-MAS, T-MAS, and progesterone concentrations and the presence or absence of MII oocytes. Interestingly, free cholesterol level was significantly lower and FF-MAS/cholesterol and progesterone/cholesterol ratios significantly higher in follicles containing MII oocytes compared to follicles from which oocytes were not retrieved. Yet, fertilization and embryo quality did not correlate with follicular sterols. This knowledge should be beneficial for the implementation of protocols for in vitro maturation process, usually used in PCOS patients.
Assuntos
Colestadienóis/metabolismo , Colestenos/metabolismo , Gonadotropina Coriônica/farmacologia , Folículo Ovariano/metabolismo , Síndrome do Ovário Policístico/metabolismo , Colestadienóis/química , Colestenos/química , Colesterol/metabolismo , Desenvolvimento Embrionário , Feminino , Fertilização in vitro , Humanos , Lanosterol/metabolismo , Metáfase , Oócitos/citologia , Folículo Ovariano/efeitos dos fármacos , Indução da Ovulação , Progesterona/metabolismoRESUMO
OBJECTIVE(S): To evaluate the effect of hysteroscopic resection of a large uterine septum (Class V according to the American Fertility Society (AFS) classification) and of a small partial uterine septum (Class VI according to AFS classification or arcuate uterus) on the abortion rate in pregnancies after IVF and ICSI. STUDY DESIGN: The retrospective matched control study included 31 women who conceived following IVF or ICSI before hysteroscopic resection of a large (12 women) or small partial (19 women) uterine septum and 106 women who conceived following IVF or ICSI after hysteroscopic resection of a large (49 women) or small partial (57 women) uterine septum. For each pregnancy in the study group, we found two consecutive pregnant control women from the IVF/ICSI registry who had a normal uterus and were matched for age, BMI, stimulation protocol and the use of IVF or ICSI and for various infertility causes. The abortion/pregnancy rate was the main outcome measure. Data on the septum length were obtained during hysteroscopic resection by comparing the length of the 1.4 cm long yellow tip of the electric knife to the length of the resected septum. RESULTS: The abortion rate before hysteroscopic metroplasty was significantly higher, both in women with a small partial septum (78.9% before resection vs. 23.7% in the normal controls, OR 12.08) and a large septum (83.3% before resection vs. 16.7% in normal controls, OR 25.00) compared to women with a normal uterus. After the surgery, the abortion rate was comparable to the abortion rate in women with normal uterus: in both women with a small partial and women with a larger septum. CONCLUSION(S): Similar to a large uterine septum, a small partial uterine septum is an important and hysteroscopically preventable risk factor for spontaneous abortion in pregnancies after IVF and ICSI.
Assuntos
Aborto Espontâneo/prevenção & controle , Fertilização in vitro , Histeroscopia/métodos , Resultado da Gravidez/epidemiologia , Injeções de Esperma Intracitoplásmicas , Útero/anormalidades , Útero/cirurgia , Aborto Espontâneo/epidemiologia , Adulto , Estudos de Casos e Controles , Feminino , Humanos , Gravidez , Taxa de Gravidez , Estudos Retrospectivos , Fatores de RiscoRESUMO
The aim of this study was to evaluate the influence of maternal age and oestradiol concentrations on blastocyst development and live birth rates in natural cycle IVF-embryo transfer. This observational study included 397 natural cycles with IVF embryo transfer for female infertility with embryo transfer on day 5. The cycles were divided into two groups according to the woman's age (<39 and > or = 39 years of age), and into two groups according to oestradiol concentrations on the day of human chorionic gonadotrophin (HCG) administration (0.4-0.49 nmol/l and 0.5-1.2 nmol/l). Comparison between the cycles in younger versus older age groups showed significant differences in blastocyst development rate, live birth rate per embryo transfer and live birth rate per cycle (55 versus 29%, 23 versus 3% and 13 versus 2% respectively) (P < 0.001). Comparison between cycles with lower versus higher oestradiol concentrations showed no significant differences in blastocyst development rate, live birth rate per embryo transfer and live birth rate per cycle (47 versus 49%, 18 versus 18%, and 11 versus 10% respectively). Advanced maternal age negatively predicts the success of natural cycle IVF, while low oestradiol concentrations on the day of HCG administration (ultrasound criteria fulfilled) do not negatively predict blastocyst development and success of natural cycle IVF.
Assuntos
Transferência Embrionária , Desenvolvimento Embrionário/fisiologia , Estradiol/sangue , Fertilização in vitro , Idade Materna , Adulto , Gonadotropina Coriônica/uso terapêutico , Feminino , Humanos , Infertilidade Feminina/tratamento farmacológico , Ciclo Menstrual/fisiologia , Gravidez , Taxa de GravidezRESUMO
The aim of this retrospective study was to evaluate the efficiency of testicular biopsy and intracytoplasmic sperm injection (ICSI) in patients with aspermia or non-obstructive azoospermia (NOA) after cancer treatment. From 1996 to 2003, 30 men with a history of cancer, affected by aspermia or NOA and without sperm cryopreserved before cytotoxic treatment underwent testicular sperm extraction (TESE). In these men, clinical, hormonal and histological characteristics were compared; 13 underwent 39 TESE-ICSI cycles using frozen-thawed testicular spermatozoa (TESE-ICSI group). In the same period, 31 ICSI cycles were performed in 20 men with aspermia or NOA using ejaculated sperm frozen before cancer treatment (ejaculated sperm-ICSI group). Fertilization, blastocyst development, pregnancy and miscarriage rates were compared between the groups. Testicular volume, serum follicle-stimulating hormone level and Johnsen score indicated complete although reduced spermatogenesis in men with aspermia and abnormal spermatogenesis in men with NOA. After TESE, sperm retrieval was positive in 92% of men with aspermia and 58% of men with NOA. In TESE-ICSI patients with NOA a significantly lower proportion of embryos developed to the blastocyst stage than in patients with aspermia and in those after ICSI with frozen-thawed ejaculated sperm (23% vs. 43% and 47%, p = 0.03 and p < 0.01 respectively). In all groups the miscarriage rates were high; in patients with aspermia and NOA, characterized by increased age, the miscarriage rate tended to be higher in spite of similar female age and female indications of infertility. In patients affected by aspermia or NOA after cancer treatment and without sperm cryopreserved before treatment, TESE-ICSI using testicular sperm provide a chance to father a child.
Assuntos
Neoplasias/complicações , Oligospermia , Injeções de Esperma Intracitoplásmicas , Separação Celular/métodos , Ejaculação , Feminino , Humanos , Infertilidade Feminina , Masculino , Neoplasias/terapia , Oligospermia/etiologia , Gravidez , Resultado da Gravidez , Estudos Retrospectivos , Preservação do Sêmen , Espermatozoides , Testículo/citologiaRESUMO
BACKGROUND: The aim of this study was to determine whether, in polycystic ovarian syndrome (PCOS) patients, HCG action prolonged for 4 h improves the action of angiogenic substances [ovarian renin angiotensin system and vascular endothelial growth factor (VEGF)], and consequently follicular maturation, oocyte quality and oocyte fertilization competence. METHODS: In this prospective study 20 patients with PCOS undergoing IVF were included. Oocyte retrieval was carried out either 34 or 38 h after HCG administration. Each follicle was analysed for prorenin, active renin, VEGF and estradiol. Oocytes were evaluated for quality (mature, immature, degenerated oocytes), as were the embryos (low or high). RESULTS: In the HCG +38 h group there were 245 follicles, and in the HCG +34 h group 240 follicles. In the HCG +38 h group, log active renin was lower (2.78 +/- 0.20 versus 2.91 +/- 0.25; P < 0.001) and VEGF higher (2276.0 +/- 790.1 versus 1946.6 +/- 954.5 pg/ml; P < 0.001). The odds ratio for obtaining oocytes from follicles was 1.6 [95% confidence interval (CI) 1.1-2.6; P = 0.02], and for developing high quality embryos 7.6 (95% CI 2.8-20.9; P < 0.001) in favour of the HCG +38 h group. CONCLUSIONS: Follicular maturation and oocyte quality are related to the intrafollicular influences of active renin and VEGF in a time-dependent manner after HCG administration, whereas fertilization competence is related to VEGF only.
Assuntos
Proteínas Angiogênicas/metabolismo , Gonadotropina Coriônica/administração & dosagem , Fertilização in vitro/métodos , Oócitos/fisiologia , Síndrome do Ovário Policístico/tratamento farmacológico , Adulto , Gonadotropina Coriônica/uso terapêutico , Embrião de Mamíferos/fisiologia , Estradiol , Feminino , Líquido Folicular/metabolismo , Humanos , Infertilidade Feminina/terapia , Oócitos/efeitos dos fármacos , Folículo Ovariano/efeitos dos fármacos , Folículo Ovariano/fisiologia , Síndrome do Ovário Policístico/complicações , Gravidez , Renina/efeitos dos fármacos , Renina/metabolismo , Injeções de Esperma Intracitoplásmicas , Fator A de Crescimento do Endotélio Vascular/efeitos dos fármacos , Fator A de Crescimento do Endotélio Vascular/metabolismoRESUMO
Fuzzy logic brings new possibilities into control, modeling, data analysis, diagnostics, decision making, and other working fields in biomedical sciences. This paper presents how fuzzy logic can be used as an alternative or supplement to statistics in biomedical analysis. It shows an adaptive neuro-fuzzy inference computing in comparison with linear and curvilinear regression. The main goal of this presentation is to involve fuzzy logic in biomedical research. Thus, we carried out a mathematical treatment of the clinical sample, semen of infertile man, with the independent variable Concentration of spermatozoa and the dependent variable Number of spermatozoa by 230 observations.
Assuntos
Biometria/métodos , Lógica Fuzzy , Interpretação Estatística de Dados , Humanos , Infertilidade Masculina/patologia , Modelos Lineares , Masculino , Modelos Biológicos , Análise de Regressão , Contagem de EspermatozoidesRESUMO
Elastase-inhibitor complex was assessed by immunoassay in the seminal plasma of 312 men attending the outpatient infertility clinic. Using receiver operating characteristic (ROC) curve analysis, elastase at the cut-off value of > or =290 ng/ml was shown to be efficient (sensitivity 79.5%, specificity 74.4%) in the detection of genital tract inflammation as defined by leukocytospermia (>1x10(6) leukocytes/ml). The prevalence of increased elastase in 292 infertile men was significantly higher (34%) as compared with that (5%) observed in 20 fertile men (P: = 0.02). Moreover, high elastase concentration (> or =290 ng/ml) was observed in 66 of the 264 men (25%) without leukocytospermia. A significant positive correlation was found between elastase concentration and patient age (r = 0.202, P: < 0.0001) and the number of leukocytes (r = 0.330, P: < 0.0001). A negative correlation was found between elastase concentration and semen volume (r = -0.146, P: = 0.01) and the percentage of spermatozoa with single-stranded DNA (r = -0.194, P: = 0.024), but there was no correlation between elastase and sperm reactive oxygen species production. A higher seminal elastase concentration was significantly associated with tubal damage in female partners (P: < 0.001). After norfloxacine antibiotic therapy, decrease in elastase concentration was observed in 15 (25%) of the 60 treated patients. Tubal damage in the partner negatively affected the response to antibiotic therapy. In conclusion, granulocyte elastase is a reliable screening test for silent genital tract inflammation of the couple. The elastase-inhibitor complex may have a protective effect in reducing sperm DNA denaturation.
Assuntos
Doenças dos Genitais Masculinos/diagnóstico , Infertilidade Masculina/enzimologia , Inflamação/diagnóstico , Elastase de Leucócito/análise , Sêmen/enzimologia , Adulto , Antibacterianos/uso terapêutico , DNA de Cadeia Simples/análise , Doenças das Tubas Uterinas/enzimologia , Feminino , Doenças dos Genitais Masculinos/tratamento farmacológico , Doenças dos Genitais Masculinos/patologia , Humanos , Infertilidade Masculina/patologia , Infertilidade Masculina/fisiopatologia , Inflamação/tratamento farmacológico , Inflamação/patologia , Contagem de Leucócitos , Masculino , Prognóstico , Espécies Reativas de Oxigênio/metabolismo , Sêmen/citologia , Sêmen/microbiologia , Contagem de Espermatozoides , Motilidade dos EspermatozoidesRESUMO
Three cases of carcinoma in situ were found by testicular biopsy among a group of 85 infertile men, most with diagnosed azoospermia. It remains difficult and unclear how to manage such patients to achieve offspring and to assure the adequate oncological therapy.
Assuntos
Carcinoma in Situ/epidemiologia , Infertilidade Masculina/complicações , Neoplasias Testiculares/epidemiologia , Adulto , Biópsia , Carcinoma in Situ/complicações , Carcinoma in Situ/patologia , Humanos , Infertilidade Masculina/patologia , Masculino , Técnicas Reprodutivas , Neoplasias Testiculares/complicações , Neoplasias Testiculares/patologia , Testículo/patologiaRESUMO
To determine whether semen quality in Slovenians has changed over 14 years (1983-96), we analysed retrospectively the semen of 2343 healthy men with a normal spermiogram, who were partners of women with tubal infertility included in the IVF-ET programme. Age at semen collection, duration of sexual abstinence, semen volume, sperm concentration, total sperm count, percentage of spermatozoa with progressive motility, and normal morphology were determined. Multiple regression analysis was used to assess the changes in sperm characteristics according to the year of semen collection, year of the man's birth and the duration of sexual abstinence. Semen volume, sperm concentration, sperm count and total sperm motility did not change between 1983 and 1996, whereas between 1988 and 1996 rapid progressive sperm motility decreased by 0.95% per year (p < 0.0001). Semen volume, sperm concentration, and sperm count increased with duration of sexual abstinence. After adjustment for the year of semen collection and duration of sexual abstinence, multiple regression analysis showed that sperm concentration decreased by 0.67% per each successive year of birth (p = 0.03). Thus the sperm concentration decreased from 87.6 x 10(6)/mL in men born in the 1940s to 77.3 x 10(6)/mL in those born between 1956 and 1960. After 1960, sperm concentration was found to increase. In 2343 healthy men, no decline in semen quality, except in rapid progressive motility, was observed in the study period. Lower sperm concentration was found among men born between 1950 and 1960. This could be related to worse socio-economic status, stress or negative environmental factors in this time period.
Assuntos
Fertilização in vitro , Infertilidade Feminina/terapia , Sêmen/fisiologia , Espermatozoides/fisiologia , Adulto , Feminino , Fertilização in vitro/estatística & dados numéricos , Humanos , Masculino , Estudos Retrospectivos , Eslovênia , Contagem de Espermatozoides , Motilidade dos EspermatozoidesRESUMO
BACKGROUND: The aim of this study was to evaluate the role of blastocyst culture in patients with azoospermia. METHODS: In 98 cycles embryos were cultured for 2 days and in 128 cycles for 5 days to reach the blastocyst stage; a maximum of two of the most developed embryos were transferred in each group. RESULTS: There was a negative correlation between a high (>/=20 IU/l) male serum FSH and embryo development, manifested as embryos not reaching the morula stage on day 5 (r = 0.387; P < 0.05). After prolonged culture, 23% of embryos reached the blastocyst stage. The pregnancy rates per transfer, and the abortion rates were approximately the same in the day 2 group and the day 5 group (20 versus 20% and 19 versus 18% respectively). After blastocyst transfer, a high clinical pregnancy rate (55%) and a low abortion rate (6%) were achieved, whereas the transfer of arrested embryos provided a low pregnancy rate (2%) and a high abortion rate (100%). If only blastocysts had been transferred on day 5, the clinical pregnancy rate per started cycle would have been approximately the same in both groups (13 versus 16%). CONCLUSIONS: Blastocyst formation is a good indicator of clinical results after ICSI with testicular sperm.
Assuntos
Blastocisto/fisiologia , Infertilidade Masculina/terapia , Oligospermia/complicações , Injeções de Esperma Intracitoplásmicas , Espermatozoides , Testículo , Aborto Espontâneo/epidemiologia , Técnicas de Cultura , Transferência Embrionária , Desenvolvimento Embrionário e Fetal , Feminino , Humanos , Incidência , Infertilidade Masculina/etiologia , Masculino , Gravidez , Taxa de Gravidez , Prognóstico , Resultado do TratamentoRESUMO
Apoptosis is a widespread phenomena during development. It represents a form of cell death and has a crucial role in tissue homeostasis. Apoptosis is also involved in a number of pathological conditions. Spermatogenesis is a dynamic process of germ cell proliferation and differentiation. During regular spermatogenesis, the number of testicular germ cells degenerate by an apoptotic process. The significance of regulating cell population by apoptosis is more apparent when sperm production is halted. The presence and frequency of apoptosis in germ cells of human testis biopsy specimens were tested. The results confirm the presence of germ cell apoptosis but not the apoptosis of Sertoli cells. The increased apoptotic index was observed in patients with azoospermia in comparison with normal but obstructed spermatogenesis.
Assuntos
Apoptose , Infertilidade Masculina/patologia , Túbulos Seminíferos/patologia , Espermatozoides/patologia , Biópsia , Humanos , Marcação In Situ das Extremidades Cortadas , Masculino , EspermatogêneseRESUMO
The aim of the present study was to assess variability in the evaluation of human sperm concentration, motility and vitality. Technicians and biologists from 10 teams involved in multicentre studies on semen quality attended the same laboratory, each team using its own methods and equipment to analyse the same semen samples. Inter-individual variability was assessed from 17 fresh semen samples of varying quality. Intra-individual variability was assessed from pools of frozen samples for sperm concentration and motility and stained smears for vitality with three blind evaluations by sample and smear. The mean inter-individual coefficients of variation were 22.9, 21.8 and 17.5% for sperm concentration, motility and vitality respectively. There was no statistical difference among participants for sperm concentration assessment, but significant differences for both motility and vitality (both P: < 0.05). The mean intra-individual coefficients of variation were 15.8, 26.2 and 13.1% for sperm concentration, motility and vitality respectively, with marked differences between expert and novice participants: concentration 9.8% versus 28.0%; motility 22.8% versus 33.0%; and vitality 10.0% versus 19.3%. The present data confirm the need for external quality control schemes for diagnostic purposes, and indicate their utmost importance in multicentre studies on semen quality.