Measurement and significance of sperm morphology

The measurement or evaluation and clinical significance of human sperm morphology has always been and still is a controversial aspect of the semen analysis for the determination of a male's fertility potential. In this review the background of the development of the evaluation criteria for sperm morphology will be discussed. Aspects of criticism on the strict criteria definition and use of the criteria for sperm morphology evaluation will be discussed as well as possible reasons for the decline in normal sperm morphology values and how we can compromise for this phenomenon resulting in the very low normal reference value as published in the 2010 WHO manual for the Examination and Processing of Human Semen. One of the possible solutions may be to give more attention to a limited number of abnormal sperm morphology categories and the inclusion of sperm morphology patterns. It is concluded in this review that if done correctly and with care and with strict application of existing guidelines as outlined in the 2010 WHO manual, sperm morphology measurement still has a very important role to play in the clinical evaluation of male fertility potential.     

《WHO人类精液检查与处理实验室手册》第5版与第4版精子形态评估标准的比较研究

目的:比较《WHO人类精液检查与处理实验室手册》第5版与第4版(以下称《WHO5》、《WHO4》)精子形态评估标准的差异,了解《WHO5》对精子形态评估标准的变化。方法:由浙江省人类精子库9名工作人员分别用《WHO5》与《WHO4》精子形态评估标准,对96张精子形态照片共计1 000个精子进行形态评估。结果:用《WHO5》标准评估的形态正常精子百分率[(26.50±5.06)%]高于用《WHO4》标准的评估[(11.39±3.17)%],差异有显著性(P<0.05);用《WHO5》标准评估的头部异常率[(64.26±7.66)%]及尾部异常率[(10.92±2.03)%]较《WHO4》[(76.11±8.13)%、(39.89±3.85)%]更低,差异有显著性(P<0.05),颈和中段异常率及过量残留胞质差异无显著性[分别为(16.46±3.08)%vs(15.22±3.51)%、(4.24±1.66)%vs(3.87±1.68)%,P>0.05]。结论:《WHO5》精子形态总体评估标准不如《WHO4》的评估标准严格,形态正常精子百分率更高。     

《世界卫生组织人类精液分析实验室技术手册》与我国男科实验室现状

2010年出版的《世界卫生组织人类精液分析实验室技术手册》第5版是最为全面的一次修订。本文结合我国男科实验室精液分析的现状,从包括精子计数、精子活力、精子形态学、精子功能、抗精子抗体和精浆生化、以及精液分析的质量保证与质量控制等7个方面,对新出版的WHO手册进行了评论。笔者认为,该手册对精子浓度分析方法和参考值下调的推荐缺乏循证医学依据;精子活力分级标准的修订和精子形态学的严格标准和较低的4%的正常参考值与我国男科实验室目前使用的标准差距较大;精子功能指标尚未完善;抗精子抗体和精浆生化指标的检测方法显然不适合我国男科实验室现状;但精液分析的质量保证和质量控制对我国男科实验室有重要指导作用。需要指出的是,WHO手册中并没有涉及来自占世界人口1/5的中国人的任何临床数据和资料。因此,尽管WHO手册非常重要,它能否适应中国人精液分析实验室参考,仍需要评估。     

评《WHO人类精液检查与处理实验室手册》(第5版)

2010年《WHO人类精液检查与处理实验室手册》(第5版)修订出版。本文就其贡献、修改和缺憾进行了评述。遗憾缺乏中国的数据与资料。正常精子形态4%难以置信和应用。笔者认为:手册不能视为"圣经",WHO的参考值是一个重要的历史记录,但绝对不是终点,而是一个新起点。创建中国特色精液分析是男科学工作者不可推卸的责任。     

按WHO《人类精液检查与处理实验室手册》第5版标准探讨精子形态对IVF-ET助孕结局的预测价值

目的:按WHO《人类精液检查与处理实验室手册》第5版(《WHO5》)标准探讨正常形态精子百分率对常规体外受精-胚胎移植的助孕结局及新生儿健康状况的预测价值。方法:采用《WHO5》标准把研究对象789例分为畸形精子症组(正常形态精子百分率<4%,35例)和正常组(正常形态精子百分率≥4%,754例),比较两组间正常受精率、卵裂率、优胚率、种植率、临床妊娠率、流产率及新生儿情况。结果:①两组间患者年龄(男、女方)、获卵数、女方平均身高及平均体重指数差异不显著(P>0.05);畸形精子症组的正常受精率、卵裂率、优胚率、周期冷冻率、种植率及移植周期妊娠率略低于正常组,而其流产率略高于正常组,但两组间各指标差异均无统计学意义(P>0.05);②除外继续妊娠(畸形精子症组1例,正常组140例),随访789个移植周期已分娩228个婴儿,畸形精子症组15个(9单胎+3双胎),正常组213个(141单胎+36双胎),出生婴儿无先天性缺陷,两组间孕周、早产率、低体重发生率差异均无统计学意义(P>0.05)。结论:按《WHO5》标准仅通过精子形态预测体外受精-胚胎移植的助孕结局及新生儿情况具有一定局限性。     

Comments on the release Laboratory Manual for the Human Semen of the 5th edition of the WHO Examination and Processing of

The authors of the World Health Organization Semen Analysis Manual are to be congratulated on producing a new edition; it is an essential tool to disseminate good practice in andrology. However, the tests described have poor prognostic power to predict a man＇s fertility and show little about the underlying causes of sub-fertility. This commentary urges a revival of research into the diagnosis of male fertility. It suggests that fertility should be regarded as a continuum and that the artificial binary division between fertile and infertile should be abandoned. Models to predict a sub-fertile couple＇s chance of conception in a year should be developed on the basis of prospective data. These models would allow for sophisticated decision making about management. The future lies in the identification of tests to detect underlying pathologies open to specific treatment. Leads such as oxidative stress, defects in the intracellular regulation and the developing field ofproteomics should be explored.     

Are conventional sperm morphology and motility assessments of predictive value in subfertile men?

Sperm morphology and motility are believed to be important prognostic factors for fertility. Results of a group of 67 men investigated for primary infertility who had mean sperm concentrations greater than 5 million per ml and who later produced pregnancies, were compared with those of 67 matched controls who remained infertile. All female partners were potentially fertile. The groups were matched for other known prognostic factors for fertility, namely, wife's age, the duration of infertility, sperm concentration and varicocele size. There were no significant differences between the two groups overall in the (mean +/- SEM)% of sperm with normal morphology (58.3 +/- 2.1; 58.5 +/- 2.2), or motility (40.6 +/- 1.8; 37.0 +/- 2.0). However, among oligospermic men from the two groups, sperm motility was significantly higher (P less than 0.05) in the subsequently fertile group (43.1 +/- 2.6%) than in the persistently infertile group (33.3 +/- 3.7). These results indicate that sperm morphology as currently assessed may not be important in predicting fertility in subfertile men with a mean sperm concentration over 5 million/ml and the % sperm motility may only be a relevant predictor in oligospermic men.     

Reassessment of sperm morphology of archival semen smears from the period 1980--1994

Several reports have suggested that sperm counts of normal men have declined in many geographical regions during the last decades. Deterioration of sperm morphology has also been reported in some studies covering long sample collecting periods. The original semen analysis data of our semen laboratory from the period 1980--1994 showed a significant decline in the proportion of spermatozoa with normal morphology. The finding was, however, questioned because of changes in sperm morphology assessment criteria during the study period. In the present study 1745 smears were re-analysed to cover evenly the whole study period. The samples were examined in random order by using strict assessment criteria. Multiple linear regression analysis of the re-analysed data showed no effect of the year of sample delivery on sperm morphology between the years 1980 and 1994. However, there was a significant decline in the proportion of normal spermatozoa with later year of men's birth.     

Intrauterine insemination in male factor subfertility: significance of sperm motility and morphology assessed by strict criteria

The study was conducted to evaluate the results of IUI treatment in a homogenous group with male factor infertility, and to assess the correlation of sperm variables, including sperm morphology by strict criteria, with pregnancy achievement after IUI. A total of 108 couples with no apparent female aetiology for infertility underwent 264 intrauterine insemination treatment cycles. A comparison was made between the sperm variables in two groups in which the achievement of pregnancy differed. The percentage of motile spermatozoa, degree of motility and normal morphology (by strict criteria) were significantly higher in the pregnant group compared with that of the nonpregnant group. A significant difference in pregnancy rates per couple after intrauterine insemination was demonstrated among three groups according to the percentage of sperm morphology, i.e. poor (< 4%), fair (4-14%) or good (> 14%) (11.1%; 36.1% and 50.0%, respectively). Intrauterine insemination is a valid mode of treatment in cases with male infertility, provided that normal morphology by strict criteria is higher than 4%.     

The relationship between critical evaluation of sperm morphology and the TYB-optimized zona free hamster oocyte sperm penetration assay

The objective of this study was to analyse the relationship between the percentage of spermatozoa in semen with normal morphology, assessed using the Tygerberg criteria, and sperm fertilizing ability assessed using the TYB-optimized zona free hamster oocyte sperm penetration assay (TYB-optimized SPA), to evaluate the predictive value of strict morphology on outcome of the SPA. In a retrospective study, 56 samples were analysed. In addition to routine semen parameters, the percentage of spermatozoa with normal morphology (A forms) and the average number of penetrations per oocyte (Sperm Capacitation Index) was evaluated in all cases. Using a multiple linear regression analysis with all semen parameters, sperm morphology was the best predictor (p = 0.001) of the SPA score. The agreement between the percentage of A forms and the Sperm Capacitation Index beyond chance (kappa coefficient) was 0.5842. Twenty-two specimens had abnormal SPA scores, with 21 exhibiting abnormal sperm morphology (Sensitivity = 96%). The remaining 34 samples had normal Sperm Capacitation Index values; of these, 23 had normal sperm morphology in semen (Specificity = 68%). The positive predictive value was 96%, and the negative predictive value was 66%. All semen samples from control donors had normal semen parameters and Sperm Capacitation Index values. In conclusion, the percentage of spermatozoa with normal morphology assessed using Tygerberg criteria (> 14% A forms) are predictive of the results in the TYB-optimized SPA. However, sperm morphology appears to be a better predictor when it is normal than when it is abnormal.     

Accuracy of the normal sperm morphology value by Sperm Quality Analyzer IIC: comparison with the strict criteria

The aim of the present study is to investigate the accuracy of the normal sperm morphology value by Sperm Quality Analyzer IIC (SQA IIC), which was developed to provide a rapid and low-cost quantitative evaluation of semen quality. Normal sperm morphology was assessed using SQA IIC in comparison with that by the strict criteria in 62 semen samples. Normal sperm morphology value by SQA IIC was based on the studies of three traditional sperm parameters from over 4000 fresh, untreated semen samples, while the strict criteria was based on the method by Kruger et al. The mean +/- SD of percent normal morphology by SQA IIC and the strict criteria were 37.6 +/- 10.9% (range 15-52) and 19.9 +/- 8.2 (range 1-34), respectively. There was a significant correlation of the sperm morphology assessment between the two methods (r=0.454, p < 0.001). Using the cut-off value of >30% normal morphology by SQA IIC, the positive predictive value and the negative predictive value of the 'normal' strict criteria were 79.6% (39/49) and 46.2% (6/13), respectively. These results indicate that SQA IIC might be used as an initial screening test for the evaluation of sperm morphology. However, sperm morphological assessment by the strict criteria should be performed in order to make decisions in planning strategies for the treatment of infertile couples.     

Predictive value of morphologically normal sperm concentration in the medium for in-vitro fertilization

Morphological evaluation of spermatozoa using strict criteria (MEUSC) and conventional sperm parameters were studied with respect to in-vitro fertilization and pregnancy outcome before and after a swim-up selection procedure. Recovered oocytes were inseminated with 50 000 progressively motile spermatozoa, and this study assess the influence of the total number of spermatozoa and of the percentage with strictly normal morphology in the insemination sample on the outcome of IVF. The results showed that the percentages of spermatozoa with normal morphology using strict criteria, both in native and in post-swim-up samples, were the best predictors of IVF outcome. Their respective cut-off points were 5% and 8%. The number of morphologically normal spermatozoa inseminated also showed a good correlation with fertilization. However, it was not possible to find a proper cut-off point for this parameter. The patients were categorized on the basis of their native and post-swim-up scores. Category 1, in which both parameters were below their respective cut-off points, showed a 7% fertilization rate and a 0% pregnancy rate. Category 3, in which both parameters were above their cut-off points, showed a 70% fertilization rate and a 23% pregnancy rate. This suggests that sperm morphology can be used as a criterion for patient selection for IVF as an aid to identification of possibly subfertile males.     

Reassessment of the accuracy of traditional sperm characteristics and adenosine triphosphate (ATP) in estimating the fertilizing potential of human semen in vivo

Receiver operating characteristic curves and accuracy parameters were computed for traditional sperm characteristics (concentration, motility, morphology) and the number of peroxidase negative cells, and the concentration of adenosine triphosphate (ATP) in semen from populations of fertile and infertile men, and men who achieved a pregnancy after varicocele treatment. The percentage and concentration per millilitre of spermatozoa with rapid linear progressive motility, and the ATP concentration, provided the best discrimination between fertile and treated fertile from infertile men. The misclassification rate was higher for sperm morphology, total progressive motility and viability, whereas sperm concentration and the total sperm count per ejaculate had the worst discriminating power. The number of peroxidase negative cells per 100 spermatozoa was highly specific in identifying men who achieved pregnancy after varicocele treatment. The lower limit of normality of sperm characteristics was remarkably different between fertile men and men achieving pregnancy after treatment or during infertility work-up.     

WHO第5版精液参考值标准的临床应用对IUI适应证谱的影响

目的:探讨WHO第5版精液参考值标准的调整对夫精宫腔内人工授精(IUI)适应证谱的影响。方法:回顾性分析我院生殖中心2012年1~7月采用WHO第4版标准111个周期IUI的临床资料(A组),和2013年1~7月采用WHO第5五版标准84个周期IUI的临床资料(B组),统计各种适应证所占百分率。结果:两组适应证比较,弱精子症差异有统计学意义[97个周期(87.4%)vs 47个周期(55.9%),P0.05]。少精子症(0vs 0)、畸形精子症[57个周期(51.4%)vs 30个周期(35.7%)]、液化异常[1个周期(0.9%)vs 0]、性功能障碍及生殖器畸形[0vs 3个周期(3.6%)]、免疫性不育[1个周期(0.9%)vs 0]和不明原因不育[4个周期(3.6%)vs 2个周期(2.4%)]差异无统计学意义(P均0.05)。结论:WHO第5版精液参考值标准的临床应用对IUI适应证谱有较大影响,造成因为男方因素行IUI的病例大幅度减少,可能会使部分患者治疗周期加长,女方诊治过度,进一步加重其经济负担和身心压力。     

Prediction of unexpectedly poor fertilization and pregnancy outcome using the strict criteria for sperm morphology before and after sperm separation in IVF-ET

This study was performed to investigate if unexpectedly poor fertilization and in-vitro fertilization (IVF) outcome could be predicted using sperm morphology as diagnosed by the strict criteria. Sperm morphology was assessed in 137 IVF-ET cycles with at least three oocytes collected. The lowest amount of normal forms was 5% in 137 samples, indicating there were no patients belonging to 'poor prognosis' (<5% normal forms). Treatment using intracytoplasmic sperm injection (ICSI) was also excluded. Before sperm separation by the swim-up method, sperm morphology demonstrated a significant correlation with the fertilization rate (p < 0.0001). The fertilization rate (80.5%) in 110 'normal' samples (>14% normal forms) was significantly higher (p < 0.01) than that (55.4%) in 27 samples with 'good prognosis' (those with 5--14% normal forms). No embryo was available for transfer (ET) in 4 (3.6%) of 110 'normal' cycles and in 3 (11.1%) of 27 'good prognosis' cycles (not significant). Fresh ET was intentionally cancelled to avoid severe ovarian hyperstimulation syndrome (OHSS) in six of 110 'normal' cycles as well as in one of 27 'good prognosis' cycles. The pregnancy rate per ET was 31.0% (31/100) in the former group, while it was 26.1% (6/23) in the latter group. There was no difference between the two groups. In the post swim-up evaluation of sperm characteristics, morphology was significantly correlated with the fertilization rate in IVF-ET (p < 0.05) while other sperm parameters were not. When the cut off level for the post swim-up sperm morphology was set at 25%, there was a significant difference in the fertilization rates between patients (78.6%) with post-swim-up >25% and those (55.0%) with post-swim-up < or =25% (p < 0.01). Taken together, a relative indication for ICSI using sperm morphology before and after swim-up was established. Category A includes < or =14% normal forms in the ejaculate and post-swim-up < or =25%, while Category B includes < or =14% in the ejaculate and post-swim-up >25%. There was a significant difference in the fertilization rates between patients (47.2%) in Category A and those (60.2%) in Category B (p < 0.05). The clinical pregnancy rate was 11.1% for patients in Category A compared with 35.7% for patients in Category B. However, there was no significant difference between the two categories. These results indicate that the strict criteria provide a reliable estimation of the fertilizing ability of human spermatozoa. ICSI might be considered in Category A patients to avoid poor fertilization and pregnancy outcome.     

Testicular function in potential sperm donors: normal ranges and the effects of smoking and varicocele

Testicular exocrine (semen analysis) and endocrine (plasma LH, FSH, prolactin and testosterone) function was assessed in 119 consecutive healthy men presenting for screening as potential sperm donors. Since these volunteers were unbiased with respect to their fertility status, this sample of the general male population was suitable to determine normal ranges and the influence of a variety of physical (height, weight, standardized body weight, varicocele) and demographic (age, marital and fertility status, tobacco and alcohol consumption) factors on normal human testicular endocrine and exocrine function, without the confounding effects of bias in selection of subjects. The statistical distribution of all seminal parameters was non-gaussian, but cube-root transformation of the data normalized the distribution, allowing for parametric statistical analysis. The median (and 95% confidence limits) for the various semen parameters was 73.0 (10.6-235.3) million sperm per ml; 189.0 (12.6-868) million sperm per ejaculate; 50.4 (5.9-181.9) million motile sperm per ml; 133.0 (6.9-661.7) million motile sperm per ejaculate; 54.0 (7.0-172.9) million morphologically normal sperm per ml and 138.5 (7.5-672) million morphologically normal sperm per ejaculate. Testicular volume was correlated positively with measures of physique such as standardized body weight (r = 0.25, P less than 0.01) and body surface area (r = 0.30, P less than 0.002), and negatively with plasma levels of FSH (r = -0.31), P less than 0.002) but not LH. Sperm output was positively correlated with testicular volume (r = 0.28, P less than 0.005) and negatively correlated with plasma FSH (r = -0.31, P less than 0.002) and plasma LH (r = -0.31, P less than 0.002). Smoking was associated with a highly significant reduction in sperm output and motility. Men with varicocele (25%) were significantly taller, had slightly lower haemoglobin levels and moderate left (but not right) testicular atrophy, but neither seminal nor hormonal parameters were different from men without varicocele. There was no difference in any markers of human testicular function between men according to marital or fertility status, grades of moderate alcohol consumption or the presence of low titres of sperm antibodies.