Dorit Manor

Changes in uterine blood flow during human pregnancy.

A transvaginal duplex Doppler ultrasonography system was used to measure blood flow characteristics in the ascending uterine artery before and during pregnancy. The system uses a 5 MHz Doppler transducer coupled to a 6.5 MHz imaging probe. There was a steady increase in volume flow rate in the left ascending uterine artery from a mean of 94.5 ml/min before pregnancy to a mean of 342 ml/min in late gestation (reflecting a 3.5-fold increase). With the assumption of equal flow on both uterine arteries, the fraction of the cardiac output that is distributed to these vessels was calculated to be 3.5% in early pregnancy and to reach 12% near term. The mean diameter of this vessel in the nonpregnant state was 1.6 mm, increasing to 3.7 mm toward term. The resistance to flow, expressed as the peak systolic to end-diastolic flow velocity ratio, declined from a mean of 5.3 in the nonpregnant state to a mean of 2.3 near term. These changes reflect the perpetual growth and development of the uteroplacental circulation, which provides the metabolic demands of the growing fetus throughout gestation.

Unequal Pronuclear Size—A Powerful Predictor of Embryonic Chromosome Anomalies

Purpose:Our purpose was to evaluate whether pronuclei of unequal size, observed in 13.7% of zygotes evaluated after in vitro fertilization (IVF), are predictive of chromosome anomalies in the developing embryo.Methods:The ploidy of 38 embryos grown from zygotes with unequal-sized pronuclei was assessed by fluorescent in situ hybridization (FISH). Twenty-six embryos developed after intracytoplasmic injection of sperm (ICSI) and 12 embryos were derived from conventional IVF.Results:Chromosome anomalies were documented in the ICSI and IVF groups in 88.5 and 50% of cases, respectively.Conclusions:We suggest that FISH should be employed to examine the ploidy of zygotes with unequal pronuclei, prior to embryo transfer.

The presence of a sponsoring embryo in a batch of poor quality thawed embryos significantly increases pregnancy and implantation rate

OBJECTIVE To evaluate quantitatively the effect of one good-quality (sponsoring) embryo in a batch of low-quality thawed embryos on the implantation and pregnancy rates (PR). DESIGN Retrospective analysis of data. SETTING Tertiary care center IVF clinic affiliated with a university medical school. PATIENT(S) Between March 1988 and April 1995, 392 IVF patients underwent a total of 440 thawing and ET cycles of 1,436 multicellular embryos. MAIN OUTCOME MEASURE(S) Implantation, clinical pregnancy, and multiple pregnancy rates. RESULT(S) In the absence of sponsoring embryos in the thawed batch of embryos, a PR of 9.8% with an implantation rate of 3.1% was achieved. In the presence of a single sponsoring embryo, the PR nearly doubled (18.2%), with a significantly higher implantation rate of 7.0%. Only singleton pregnancies were achieved in the absence of sponsoring embryos compared with 21.7% multiple pregnancies in the single sponsoring embryo group. CONCLUSION(S) The presence of a sponsoring embryo in a batch of poor quality thawed embryos is an important factor that significantly increased pregnancy and implantation rates. The optimal strategy for planning batches of multicellular frozen embryos is to include at least one sponsoring embryo in each batch when possible. We speculate that the sponsoring embryo may favorably influence the chances of low-quality embryos to undergo successful implantation.

Basic principles and clinical applications of the transvaginal Doppler duplex system in reproductive medicine

ConclusionNew technological advances in the field of ultrasound imaging and in Doppler signal acquisition and analysis help to open new fields of investigation in reproductive medicine. One such example is the recent introduction of the transvaginal Doppler duplex system, which can be applied as a sensitive, noninvasive “flow probe” to evaluate hemodynamic changes in pregnant and nonpregnant patients. Another important development is the application of Doppler color flow mappping, which facilitates vessel recognition and localization. Such instruments are expensive at present and are mostly limited for research purposes. Further developments are likely to emerge once new instruments and new methods of data analysis become available. Further increases in image resolution and improved Doppler signal generation and processing will enable more accurate flow measurements. Another important field is invasive flow measurement, which could be developed for intraoperative and intravascular investigations, based on specialized probes and catheter-mounted transducers. At present further investigations are required for defining the normal ranges in the population and for establishing abnormal patterns. Once causative mechanisms are defined, various treatments may be offered, while monitoring the changes using the techniques described here.

The use of GnRH analogs for induction of the preovulatory gonadotropin surge in assisted reproduction and prevention of the ovarian hyperstimulation syndrome

Ovarian hyperstimulation syndrome (OHSS) remains a potential severe complication of the use of gonadotropin therapy in ovulation induction and assisted reproduction technologies. In 1988, we reported preliminary results which demonstrated the ability of gonadotropin-releasing hormone analogs (GnRH-a) to trigger ovulation, and to prevent subsequent OHSS. In this report, we summarize our experience of 73 treatment cycles involving 44 high responders (i.e. patients with a previous history of severe OHSS, or with high estradiol levels (> 13 200 pmol/l) on the day of triggering the luteinizing hormone (LH) surge).In spite of the high estradiol levels (mean 24 202 pmol/l) and the large number of oocytes (mean 32.4), none of our patients developed severe OHSS. Luteal support with progesterone and estradiol valerate was necessary to maintain adequate serum levels of these hormones. Without such support, a precipitous decline in levels of estradiol and progesterone was observed. We believe that the use of GnRH-a i...

Assisted implantation : Direct intraendometrial embryo transfer

We report herein a technique for direct intraendometrial transfer (DIET) of human embryos. In this study we evaluated whether 2-day embryos injected into the endometrial stroma can develop normally into viable pregnancies. After in vitro fertilization the embryos were injected into the endometrium of 14 women under direct visualization using a CO2-pulsed flexible hysteroscope. A total of 44 embryos were transferred, resulting in 2 clinical (14.3% per cycle) and 2 chemical pregnancies. In 1 patient, amniocentesis revealed monosomy X and the pregnancy was terminated at 18 weeks. The 2nd patient had an uneventful pregnancy and delivered a healthy baby. The results from the present study, demonstrating a low implantation rate after DIET of 2-day embryos, suggest that the endometrial stroma does not provide an optimal environment for early embryonic development. The acidifying effect of CO2 used for insufflation may also explain the low pregnancy rate after DIET. We conclude that it is possible to achieve pregnancy by DIET in humans, but presently this procedure can be considered only in cases where the implantation site needs to be precisely determined.

Human sperm and hamster oocyte interaction: a model system to assess sperm entry into the oocyte after partial zona dissection

A model system of hamster oocyte and human sperm interaction was used to assess sperm entry into the perivitelline space after partial zona dissection. The procedure of zona dissection was standardized by creating slits which included one fourth, one eighth, one eighth X 2, or one sixteenth of the zonal circumference. Manipulated eggs were allowed to interact with 1 X 10(6) sperm/mL for 3 hours. A single large or medium slit was equally effective in permitting sperm entry into 46% and 47% of the manipulated eggs, respectively. However, the longer slit doubled the average number of sperm detected in the perivitelline space. A second medium-sized slit increased the rate of sperm entry into the perivitelline space to 76%, but the incidence of damaged oocytes also increased. A small slit did not permit sperm entry into any of the manipulated oocytes. This heterologous system of gamete interaction provides a model to evaluate requirements for successful partial zona dissection or other related procedures for assisted fertilization in the human.

Preimplantation Diagnosis by FISH: The Rambam Experience

Purpose:Our purpose was to summarize our experience gained using fluorescence in situ hybridization for preimplantation diagnosis at the Rambam Medical Center.Methods:Seventy-three embryos (29 cycles) were analyzed for preimplantation diagnosis for the following indications: advanced maternal age (>39 years), X-linked diseases, poor-quality embryos, repeated failure in vitro fertilization cycles and fast-dividing embryos. An additional 38 embryos with unequal pronuclei size were examined for ploidy. Biopsy of embryonic blastomeres was performed at the six- to eight-cell stage. Five fluorescence probes, for chromosomes X, Y, 13, 18, and 21, were applied for ploidy detection.Results:Eighty-four (87%) blastomeres of the 73 embryos analyzed showed clear signals. Six of the blastomeres were lost during spreading. Two of the embryos were destroyed following biopsy. No nucleus was found in five of the blastomeres, while in nine, more than one nucleus was verified. Transfer was performed in 10 patients (32 embryos). Two pregnancies were achieved. Two healthy babies were born. Fifty-seven percent of the fast-dividing embryos demonstrated normal signals. In two groups of embryos of unequal pronuclei size, following conventional insemination and intracytoplasmic sperm injection, 50 and 11.4% demonstrated normal signals.Conclusions:The efficiency of florescence in situ hybridization for aneuploidy detection is 87 and 97% for autosomes and gonosomes, respectively. The preimplantation genetic diagnosis is suitable for selected in vitro fertilization cases including fast-dividing embryos and embryos with unequal pronuclei size following regular in vitro fertilization.

Subcloning and Alternative Methods for the Derivation and Culture of Human Embryonic Stem Cells

Human embryonic stem (ES) cell lines may have broad applications, including the study of development and the differentiation process, lineage commitment, self-maintenance, and precursor cell maturation. They may also serve as models in research done on the functions of genes and proteins, drug testing, and drug toxicity. The first human ES cells were derived by Thomson and colleagues (1) from the inner cell mass (ICM) of surplus blastocysts donated by couples undergoing in vitro fertilization treatments. These lines met most of the criteria for ES cell lines listed in Table 1, but their clonality was not tested in that study. Also, the ability of human ES cells to contribute to embryonic development in chimeric embryos cannot be examined for obvious ethical reasons. Since the first report on human ES cell derivation, several other groups have reported the derivation of additional lines (2–4) At present, there are more than 70 human ES cell lines in several laboratories around the world, according to a list published by the National Institutes of Health (NIH; http://www.nih.gov/news/stemcell/index/news/stemcell/index). Although the NIH list does not offer full information on all the lines fulfilling all the ES cell criteria listed in Table 1, it suggests that the derivation of human ES cells is a reproducible procedure with reasonable success rates.

Blood Flow Measurements in the Uterine and Ovarian Arteries in Patients Undergoing IVF/ET and in Early Pregnancy, Performed with a Transvaginal Doppler Duplex System

Recent technological advances in ultrasound imaging have contributed greatly to patient care in the fields of obstetrics and gynecology. Of particular importance was the recent development of the high frequency transvaginal sonography, which is emphasized by its extensive application in in vitro fertilization and embryo transfer (IVF/ET) programs. Such applications include monitoring of follicular development, follicle aspiration and scanning of the endometrium, the ovaries and other normal and abnormal pelvic structure. An extensive review on this subject is given elsewhere.1