Lynette Scott

Pronuclear scoring as a predictor of embryo development

Many strategies have been proposed for the selection of viable embryos for transfer in human assisted reproduction. These have included morphological scoring criteria for day 1, 2, 3 and 5 embryos or combinations of these. Other strategies have used predictors such as timing of certain key events, as with early cleavage to the 2-cell, development to the 8-cell stage or patterns of fragmentation. All have shown some correlations with implantation. However, the overall success of these methods is still limited, with over 50% of all transferred embryos failing to implant. The use of pronuclear oocyte morphology has shown correlations with implantation and development to the blastocyst stage. The key aspects of pronuclear scoring, namely the presence of a cytoplasmic halo, the orientation of the nuclei in relation to the polar bodies and the size, number and pattern of distribution of nucleolar precursor bodies (NPB) in the nuclei were related to day 2,3 and 5 development, rate of development and day 3 and 5 morphology in a retrospective study. The pattern of the NPB or Z-score and the presence/absence of a halo had a significant effect on the rate of development on day 3 and day 5 and on the overall embryo morphology score. Low Z-score resulted in slow development, poor blastocyst formation and low morphology scores. The absence of a halo also resulted in slow and poor development, poor morphology, increased fragmentation and increased numbers of poor Z-scored embryos. The use of PN scoring can help predict embryos that have poor developmental potential, aid in early selection and may indicate the health of the oocyte.

Pregnancy rates after embryo transfer depend on the provider at embryo transfer

OBJECTIVE To evaluate the effect of individual providers on pregnancy outcome after embryo transfer. DESIGN Retrospective data analysis. SETTING University-based tertiary-care assisted reproductive technology program with 10 physician-providers. PATIENT(S) Six hundred and seventeen women who underwent 854 fresh embryo transfers between January 1996 and January 1999. INTERVENTION(S) Pregnancies after embryo transfer were recorded for each provider. MAIN OUTCOME MEASURE(S) Establishment of a clinical pregnancy. RESULT(S) Three hundred ninety-three clinical pregnancies resulted from 854 embryo transfers, for an overall clinical pregnancy rate of 46.0% per embryo transfer. Three hundred forty-seven (40.6%) pregnancies were ongoing. The clinical pregnancy rate varied significantly between providers: for example, 17.0% (47 transfers) vs. 54.3% (57 transfers) (P<.05). Similarly, the ratio of high-grade embryos required to produce a gestational sac differed between providers. The number or quality of embryos transferred did not differ significantly. CONCLUSION(S) Significant differences were observed in pregnancy rates after embryo transfer done by different providers, suggesting that embryo transfer technique may influence pregnancy outcome in assisted reproductive technology.

The Istanbul consensus workshop on embryo assessment: proceedings of an expert meeting

This paper reports the proceedings of an international consensus meeting on oocyte and embryo morphology assessment. Following background presentations about current practice, the expert panel developed a set of consensus points to define the minimum criteria for oocyte and embryo morphology assessment. It is expected that the definition of common terminology and standardization of laboratory practice related to embryo morphology assessment will result in more effective comparisons of treatment outcomes. This document is intended to be referenced as a global consensus to allow standardized reporting of the minimum dataset required for the accurate description of embryo development. This paper reports the proceedings and outcomes of an international consensus meeting on human oocyte and embryo morphology assessment. An expert panel developed a series of consensus points to define the minimum criteria for such assessments. The definition of common terminology, and standardization of laboratory practices related to these morphological assessments, will permit more effective comparisons of treatment outcomes around the world. This report is intended to be referenced as a global consensus to allow standardized reporting of the minimum descriptive criteria required for routine clinical evaluations of human embryo development in vitro.

Human oocyte respiration-rate measurement – potential to improve oocyte and embryo selection?

Oocyte and embryo selection are not highly successful, with fewer than 10% of oocytes in assisted reproduction resulting in a delivery. Techniques for oocyte and embryo selection rely on highly subjective morphology assessment, with few true quantitative techniques available. One aspect of oocyte health that could be considered is the ability to produce ATP through respiration. Using a non-invasive technology, the respiration rates of individual human oocytes were recorded in an attempt to correlate respiration and oocyte health with probable subsequent development. Oocytes used were either immature or mature, non-fertilized oocytes from a clinical assisted reproduction programme. Differences in respiration rates between oocytes within a cohort and between cohorts of oocytes were recorded. The differences between cohorts reflected many of the currently known differences in oocyte health, related to age and FSH concentrations. However, within a cohort, differences between oocytes were observed, with some having high rates and others low. Oocytes with respiration rates of between 0.48 and 0.55 nl O(2)/h were viable, with lower rates consistent with lack of continued in-vitro maturation or atresia. This technology may have a future in the clinical laboratory as a predictor of oocyte health and ability to develop into an embryo with greater potential of delivery.

Use of postseparation sperm parameters to determine the method of choice for sperm preparation for assisted reproductive technology

OBJECTIVE To evaluate strict sperm morphology after preparation of semen specimens using three different sperm separation techniques, since strict morphology correlates well with IVF. DESIGN Semen from 30 men were analyzed before and after sperm separation using mini-Percoll gradient, direct swim-up, and SpermPrep filtration column (ZBL, Inc., Lexington, KY) methods. SETTING Assisted Reproductive Technology laboratory at Sinai Hospital of Baltimore. MAIN OUTCOME MEASURES Primary end points measured were percent morphologically normal sperm and percent improvement in sperm morphology, using Kruger strict criteria. Secondary factors determined were percent motility, improvement in motility, hypoosmotic swelling, improvement in hypoosmotic swelling, and 24- and 48-hour sperm survival under simulated IVF conditions. RESULTS Mini-Percoll produced specimens with significantly greater normal sperm morphology, morphology improvement, motility, hypoosmotic swelling, and survival than obtained with the other two separation methods. For 25 of 30 specimens, mini-Percoll yielded the greatest number of morphologically normal, motile sperm that survived for 24 hours. In four instances, mini-Percoll was associated with an increased percentage of acrosomal abnormalities despite an overall improvement in morphology. Hypoosmotic swelling scores were lower in two subjects after mini-Percoll sperm separation and in three subjects for each of the other methods. CONCLUSIONS Data suggest that mini-Percoll is superior to swim-up or SpermPrep for producing specimens with enhanced morphology, motility, and in vitro survival. However, no single separation technique is always superior, and methodology may induce damage to the acrosome or sperm membranes. Sperm specimens should be evaluated individually to determine the best separation method before actual ART cycles. The technique that yields the most morphologically normal, motile sperm that survive in culture should be used for ART procedures.

Mouse in vitro fertilization, embryo development and viability, and human sperm motility in substances used for human sperm preparation for assisted reproduction

OBJECTIVE To investigate the endotoxin content and effects on mouse IVF and embryo development and human sperm motility of human sperm separation substances. DESIGN One-cell and zona-free two-cell mouse embryo bioassays and Limulus Amoebocyte Lysate endotoxin tests and mouse oocyte parthenogenetic activation, IVF, preimplantation and postimplantation embryo development, and human sperm motility were performed in control medium or medium containing Percoll, Nicodenz, or the washings from Sperm Prep sephadex columns. SETTING Research Laboratories, Sinai Hospital of Baltimore, Baltimore, Maryland. MAIN OUTCOME MEASURE(S) Endotoxin levels, embryo development, and sperm motility. RESULT(S) Mouse embryo bioassays indicated negative endotoxin levels in Percoll and Nicodenz but Limulus Amoebocyte Lysate assays had positive gel formation. Mouse IVF and preimplantation development was equivalent in control and Percoll- and Nicodenz-containing medium; none had parthenogenetic properties but postimplantation development was reduced for embryos grown in the presence of Percoll or Nicodenz. Human sperm remained motile in the presence of Percoll or Nicodenz. Sperm Prep column washes were toxic to mouse gametes and embryos and human sperm and had gel formation with the Limulus Amoebocyte Lysate assay. CONCLUSION(S) Percoll and Nicodenz, but not Sperm Prep sephadex column washes, were compatible with mouse preimplantation and postimplantation embryo development and human sperm motility.

Embryological strategies for overcoming recurrent assisted reproductive technology treatment failure.

In every assisted reproductive technology (ART) programme there are patients who experience repeated failure. If all laboratory and stimulation parameters are controlled, it is assumed that the underlying cause of failure is physiological, and is attributable to either of the gametes or the embryo. Within the laboratory, few tools are available, other than careful observation and embryo selection, to aid in selecting the right embryo to overcome this failure. The morphology of the zygote, the state of the cleaving embryos on day 2 and day 3 of development, and the blastocyst can influence implantation rates. However, without functional gametes it is unlikely that success can be achieved. An early indicator of this functionality is the morphology of the zygote, which can be influenced by either the oocyte or the spermatozoon, and can be altered by either improving oocyte quality during stimulation or by using donor sperm if the failure to conceive is attributable to the male gamete. Subsequently, selecting embryos for transfer on the basis of the morphology of zygotes and embryos at day 3 or day 5 of development with the addition of fragmentation scoring and assisted hatching has been found to overcome many cases of repetitive failure to conceive after ART.

Human chorionic gonadotropin levels after blastocyst transfer are highly predictive of pregnancy outcome.

OBJECTIVE To determine the predictive value(s) of beta-hCG serum levels for pregnancy outcome following blastocyst transfer. DESIGN Retrospective review. SETTING University-based assisted reproductive technology (ART) program. PATIENTS All ART patients enrolled from January 1998 to December 1999. INTERVENTION(S) None. MAIN OUTCOME MEASURE(S) Beta-hCG serum levels and pregnancy outcomes. RESULT(S) Of the 836 ART cycles initiated, 608 embryo transfers met study criteria and were assigned to one of two groups: 248 day 5 blastocyst transfers or 360 day 3 embryo transfers. In the day 5 blastocyst group, 147 pregnancies occurred (59.2%), and day 3 transfers resulted in 165 pregnancies (45.8%). For day 3 and day 5 transfers, mean values of beta-hCG on day 16 post-retrieval of spontaneous abortions were lower than ongoing pregnancies (P< .05). A beta-hCG value on day 16 of >300 mIU/mL predicted an ongoing pregnancy for day 5 transfer group in 97% of pregnancies compared with 92% for day 3 embryo transfers. A multiple gestation was observed in 70% of pregnancies with a beta-hCG level >400 mIU/mL in the day 5 group compared with 63% for the day 3 group. The incidence of higher-order multiple gestations was significantly lower in the day 5 blastocyst group (P< .05). CONCLUSION(S) Beta-hCG serum levels on day 16 post-retrieval were highly predictive of pregnancy outcome after a blastocyst transfer.

Combined intrauterine triplet and ectopic pregnancy following pronuclear embryo transfer in a patient with elevated serum progesterone during ovulation induction

We present a case of heterotopic pregnancy occurring after ET of pronuclear-stage embryos. This case demonstrates that pronuclear embryos have a good implantation potential and suggests that the potentially adverse effect of high follicular-phase serum progesterone levels on endometrial development might be offset by early ET of pronuclear embryos. This, however, is speculative and deserving of formal scientific evaluation. Finally, we are reminded that heterotopic pregnancy complicates 1 to 3% of IVF-ET pregnancies and that, even with a high index of suspicion, most heterotopic pregnancies are diagnosed after rupture. All assisted reproductive programs should be reminded frequently that ectopic and heterotopic pregnancies do occur and can lead to serious consequences if left undetected.