In most in-vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI) programmes approximately one ongoing pregnancy in three is multiple. The need to characterize embryos with optimal implantation potential is obvious. We retrospectively examined all of 23 double transfers resulting in ongoing twins, occurring between January 1, 1996 and May 19, 1997. Characteristics of these top quality embryos were absence of multinucleated blastomeres, four or five blastomeres on day 2, seven or more cells on day 3, and 2 embryos, 11/31 (35%) were multiple. We applied our top quality criteria to the 221 double transfers: 106 transfers with two top embryos resulted in 65 (63%) ongoing pregnancies with 37 (57%) twins, 65 transfers with one top embryo in 38 (58%) ongoing pregnancies with eight (21%) twins. In the group without top embryos, 12/52 (23%) ongoing singletons occurred, with no twins. The corresponding ongoing implantation rates were 49, 35 and 12%. This analysis suggests that single embryo transfer with an acceptable pregnancy rate might be considered if a top quality embryo is available.

A prospective randomized study comparing single embryo transfer with double embryo transfer after in-vitro fertilization or intracytoplasmic sperm injection (IVF/ICSI) was carried out. First, top quality embryo characteristics were delineated by retrospectively analysing embryos resulting in ongoing twins after double embryo transfer. A top quality embryo was characterized by the presence of 4 or 5 blastomeres at day 2 and at least 7 blastomeres on day 3 after insemination, the absence of multinucleated blastomeres and <20% cellular fragments on day 2 and day 3 after fertilization. Using these criteria, a prospective study was conducted in women <34 years of age, who started their first IVF/ICSI cycle. Of 194 eligible patients, 110 agreed to participate of whom 53 produced at least two top quality embryos and were prospectively randomized. In all, 26 single embryo transfers resulted in 17 conceptions, 14 clinical and 10 ongoing pregnancies [implantation rate (IR) = 42.3%; ongoing pregnancy rate (OPR) = 38.5%] with one monozygotic twin; 27 double embryo transfers resulted in 20 ongoing conceptions with six (30%) twins (IR = 48.1%; OPR = 74%). We conclude that by using single embryo transfer and strict embryo criteria, an OPR similar to that in normal fertile couples can be achieved after IVF/ICSI, while limiting the dizygotic twin pregnancy rate to its natural incidence of <1% of all ongoing pregnancies.

We describe 47 patients with Angelman syndrome (AS) from Belgium and the Netherlands, including the anamnestic data, the clinical and the behavioral attributes at different ages. The clinical picture of AS is most distinct between the ages of 2-16 years. Most patients of this age group show at least 8 of the major characteristics (bursts of laughter, happy disposition, hyperactive behaviour, microcephaly, brachycephaly, macrostomia, tongue protrusion, mandibular prognathism, widely spaced teeth, stiff and puppetlike movements, typical stature, wide based gait) beside the mental retardation and (almost) absence of speech, which is a universal trait. The diagnosis in infants is based on only a limited number of clinical characteristics or on anamnestic data. However, if these occur in combination, they are indicative of AS. In older patients, the diagnosis may be hampered in part because of the changing behavioral characteristics and the decreasing frequency of fits. Other manifestations, such as scoliosis, may become more pronounced with age.

This prospective health economic study shows that transfer of a single top quality embryo is equally effective as, but substantially cheaper than, double embryo transfer in women <38 years of age in their first IVF/ICSI cycle.

Judicious application of eSET can halve the twinning rate while maintaining the overall pregnancy rate.

For optimal embryo selection in IVF/intracytoplasmic sperm injection (ICSI), knowledge of the implantation potential is essential. This is a retrospective analysis of morphological characteristics and cleavage kinetics of day 3 embryos resulting in an objective assessment of the relative implantation potential of each distinct type of embryo. Therefore transferred embryos were sampled according to their documented implantation behaviour: all embryos without any implantation on the one hand and all those with 100% ongoing implantation on the other. There were 213 such embryos in the latter group of which only seven (3%) had >20% fragmentation and only one embryo (0.5%) showed multinucleation (an embryo containing >20% fragmentation). For this reason, only embryos with < or =20% fragmentation and without multinucleation were analysed. They were split up according to the amount of fragmentation and the number of blastomeres on day 2 and on day 3. For each type, the implanted fraction was calculated, i.e. the number certainly implanted divided by the sum of the number certainly implanted and the number certainly not implanted, thus describing its relative implantation potential. By extrapolation to the entire population it was possible to establish the implantation potential for each type of embryo. Optimal day 3 embryos were calculated to reach a mean of 47% ongoing implantation. By establishing the implantation potential for most embryos, this model also provides useful information about which embryos are worth freezing in a cost-effective cryopreservation policy.

Good prognosis patients, in whom SET is applied, do not only have a higher chance of conception but do not have an unfavourable outcome of their singleton baby when compared to spontaneous singletons.

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