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Predictive value of oocyte morphology in human IVF: a systematic review of the literature

Posted: December 13, 2010 at 2:58 pm

BACKGROUND

Non-invasive selection of developmentally competent human oocytes may increase the overall efficiency of human assisted reproduction and is regarded as crucial in countries where legal, social or religious factors restrict the production of supernumerary embryos. The purpose of this study was to summarize the predictive value for IVF success of morphological features of the oocyte that can be obtained by light or polarized microscopic investigations.

METHODS

Studies about oocyte morphology and IVF/ICSI outcomes were identified by using a systematic literature search.

RESULTS

Fifty relevant articles were identified: 33 analysed a single feature, 9 observed multiple features and investigated the effect of these features individually, 8 summarized the effect of individual features. Investigated structures were the following: meiotic spindle (15 papers), zona pellucida (15 papers), vacuoles or refractile bodies (14 papers), polar body shape (12 papers), oocyte shape (10 papers), dark cytoplasm or diffuse granulation (12 papers), perivitelline space (11 papers), central cytoplasmic granulation (8 papers), cumulus–oocyte complex (6 papers) and cytoplasm viscosity and membrane resistance characteristics (2 papers). None of these features were unanimously evaluated to have prognostic value for further developmental competence of oocytes.

CONCLUSIONS

No clear tendency in recent publications to a general increase in predictive value of morphological features was found. These contradicting data underline the importance of more intensive and coordinated research to reach a consensus and fully exploit the predictive potential of morphological examination of human oocytes.

Recommendation and review posted by G. Smith

AMH and AFC as predictors of excessive response in controlled ovarian hyperstimulation: a meta-analysis

Posted: December 13, 2010 at 2:58 pm

BACKGROUND

Anti-Mullerian hormone (AMH) is a marker of ovarian reserve status and represents a good predictor of ovarian response to ovarian hyperstimulation. The aim of this study was to assess the accuracy of AMH and antral follicle count (AFC) as predictors of an excessive response in IVF/ICSI treatment.

METHODS

A systematic review and meta-analysis of the existing literature was performed. Studies were included if 2 x 2 tables for the outcome excessive response in IVF patients in relation to AMH/AFC could be constructed. Using a bivariate meta-analytic model, both summary point estimates for sensitivity and specificity were calculated, as well as summary ROC curves. Clinical value was analysed by calculating post-test probabilities of excessive response at optimal cut-off levels, as well as the corresponding abnormal test rates.

RESULTS

Nine studies reporting on AMH and five reporting on AFC were found. Summary estimates of sensitivity and specificity for AMH were 82 and 76%, respectively, and 82 and 80%, respectively, for AFC. Comparison of the summary estimates and ROC curves for AMH and AFC showed no statistical difference. Abnormal test rates for AMH and AFC amounted to ~14 and 16%, respectively, at cut-off levels where test performance is optimal [likelihood ratio for a positive result (LR + )>8], with a post-test probability of ±70%.

CONCLUSIONS

Both AMH and AFC are accurate predictors of excessive response to ovarian hyperstimulation. Moreover, both tests appear to have clinical value. This opens ways to explore the potential of individualized FSH dose regimens based on ovarian reserve testing.

Recommendation and review posted by G. Smith

Positioning to get out of meiosis: the asymmetry of division

Posted: December 13, 2010 at 2:58 pm

BACKGROUND

During meiosis, mammalian oocytes undergo two successive cell divisions without an intermediate replicative phase. This brief period, called ‘meiotic maturation’, is crucial for the formation of an egg capable of being fertilized and of generating viable and euploid offspring.

METHODS

We review our current knowledge of the cellular and molecular mechanisms that control asymmetry and appear to be shared between mammalian species, as well as the associated misfunctions that impair the formation of functional female gametes.

RESULTS AND CONCLUSIONS

The two successive divisions that comprise mammalian oogenesis are asymmetric. They lead to the formation of small polar bodies and the large and polarized egg. This asymmetry depends upon the dynamic organization of the oocyte cytoskeleton during both divisions. During meiosis I, microfilaments and associated molecules ensure the targeting of the microtubule spindle at the oocyte periphery. During meiosis II, they anchor the spindle under the plasma membrane. In parallel, the cortex overhanging the spindle is dramatically reorganized. Establishment and maintenance of this cortical domain are crucial for the completion of fertilization. Loss of this differentiated area is characteristic of ageing or low-quality gametes and associated with increased maternal age or post-ovulatory ageing.

Recommendation and review posted by G. Smith

Effects of cigarette smoking on reproduction

Posted: December 13, 2010 at 2:58 pm

BACKGROUND

Cigarette smoking is associated with lower fecundity rates, adverse reproductive outcomes and a higher risk of IVF failures. Over the last few decades, prevalence of smoking among women of reproductive age has increased. This review focuses on current knowledge of the potential effects of smoke toxicants on all reproductive stages and the consequences of smoke exposure on reproductive functions.

METHODS

We conducted a systematic review of the scientific literature on the impact of cigarette smoking and smoke constituents on the different stages of reproductive function, including epidemiological, clinical and experimental studies. We attempted to create hypotheses and find explanations for the deleterious effects of cigarette smoke observed in experimental studies.

RESULTS

Cigarette smoke contains several thousand components (e.g. nicotine, polycyclic aromatic hydrocarbons and cadmium) with diverse effects. Each stage of reproductive function, folliculogenesis, steroidogenesis, embryo transport, endometrial receptivity, endometrial angiogenesis, uterine blood flow and uterine myometrium is a target for cigarette smoke components. The effects of cigarette smoke are dose-dependent and are influenced by the presence of other toxic substances and hormonal status. Individual sensitivity, dose, time and type of exposure also play a role in the impact of smoke constituents on human fertility.

CONCLUSIONS

All stages of reproductive functions are targets of cigarette smoke toxicants. Further studies are necessary to better understand the deleterious effects of cigarette smoke compounds on the reproductive system in order to improve health care, help to reduce cigarette smoking and provide a better knowledge of the molecular mechanisms involved in reproductive toxicology.

Recommendation and review posted by G. Smith

Risk for postpartum depression associated with assisted reproductive technologies and multiple births: a systematic review

Posted: December 13, 2010 at 2:58 pm

BACKGROUND

It has been hypothesized that certain obstetrical populations, including women who conceive using assisted reproductive technologies (ART) and women with multiple births, may be at increased risk for postpartum depression. In this systematic literature review, we examine the published evidence for this hypothesis.

METHODS

The databases Medline, CINAHL, EMBASE, PsycINFO and the Cochrane Library were searched from their start dates through to April 1, 2009 using relevant keywords. All published, peer-reviewed articles in English, Spanish or French including a standardized assessment of depression administered between 2 and 52 weeks postpartum were considered for inclusion. Two independent reviewers abstracted and critically appraised a total of 13 eligible articles.

RESULTS

The data indicate little or no increased risk for postpartum depression among women who use ART to conceive. In contrast, most studies of adequate quality indicate that mothers of multiples may be at elevated risk for symptoms of depression. However, existing data do not permit differentiation between transient maternal distress and clinically significant postpartum depression.

CONCLUSIONS

Studies included in this review were often limited by small samples and lack of appropriate comparison groups, making further research in this area essential. In particular, lack of control for maternal psychiatric history and other important sociodemographic predictors of depression is a serious limitation of existing research on this topic. Further, the use of reproductive technologies and multiple births often co-occur, and few study designs enabled separation of the effects of these two variables. However, evidence of increased risk for symptoms of postpartum depression among women with multiple births, if confirmed, may warrant targeted interventions for this population.

Recommendation and review posted by G. Smith

Global variations in the uptake of single embryo transfer

Posted: December 13, 2010 at 2:58 pm

BACKGROUND

Single embryo transfer (SET) is the most effective way of reducing multiple pregnancy rates associated with assisted reproductive technology (ART). Despite published evidence suggesting that the judicious use of elective SET can lead to near-elimination of multiples without compromising cumulative live birth rates, the uptake of this strategy has been variable.

METHODS

Medline, EMBASE and the Cochrane Database of Systematic Reviews (1978–2010) were searched using appropriate MeSH headings. Leading fertility journals along with appropriate cross references were hand searched and information retrieved from national ART registers and websites of national fertility societies in order to determine current rates of SET. We explored social, economic and clinical factors determining the uptake of SET.

RESULTS

It was not possible to distinguish elective from non-elective SET from national ART reports. Data from 31 countries suggest that there has been a gradual increase in SET rates over a 3 year period (2003–2005) but major geographical differences were noted. SET rates are highest in Sweden (69.4%) but are as low as 2.8% in the USA. Access to public funding for ART, availability of good cryopreservation facilities and legislation appear to be the most important reasons favouring the uptake of SET. Personal choice plays a significant role as many subfertile couples have a strong preference for twins. Awareness that double embryo transfer (DET) increases live birth per fresh treatment cycle, inability to accurately identify women at high risk for twins and limitations of existing embryos selection criteria are barriers to a wider acceptance of SET.

CONCLUSIONS

The current variation in the uptake of elective SET is likely to persist until there are major changes in the way ART is viewed, funded and legislated.

Recommendation and review posted by G. Smith


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