Robert A. Leerentveld
Erasmus University Rotterdam
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Featured researches published by Robert A. Leerentveld.
Obstetrics & Gynecology | 1990
Robert A. Leerentveld; Erik C. A. M. Gilberts; Marinus J. C. W. J. Arnold; Juriy W. Wladimiroff
Transvaginal sonographic localization of the placenta was performed in 100 patients suspected of having placenta previa. Except in one patient, the diagnosis was confirmed at cesarean delivery in all cases of placenta previa found by sonography before delivery, resulting in a 93.3% predictive value of a positive test. The predictive value of a negative test was 97.6%; in two patients a low-insertion placenta diagnosed by sonography was found to be a placenta previa at delivery. The sensitivity and specificity of the technique were 87.5 and 98.8%, respectively. Although in some instances transvaginal sonography was performed during vaginal hemorrhage, aggravation of bleeding was never observed. Transvaginal sonographic localization of the placenta proved to be an accurate and safe diagnostic procedure.
Fertility and Sterility | 1994
Gerritdina J. Huisman; Albert Th. Alberda; Robert A. Leerentveld; Arie Verhoeff; Gerard H. Zeilmaker
Embryo transfer results after a 2 to 4 day period of embryo culture were compared. Two thousand two hundred ninety-seven ETs, performed in 1991 and 1992, were analyzed. Ongoing pregnancy rates after 2, 3, or 4 days of embryo culture were 23.3%, 21.9%, and 26.4%, respectively. Multiple pregnancy rates were 36.2%, 38.8%, and 32.6% per ongoing pregnancy for the three groups, respectively. The implantation rate of 73 cavitating morulae on day 4 was surprisingly high (41%) compared with that of other developmental stages. Transfer after 4 days of culture gives the ability to recognize embryos with a very high implantation potential.
Fertility and Sterility | 1989
Heleentje C. van Os; Albert Th. Alberda; H.A.B. Janssen-Caspers; Robert A. Leerentveld; Michael C.W. Scholtes; Gerard H. Zeilmaker
This prospectively randomized study compares the outcome of 434 ETs 48 to 52 hours after insemination (day 2) and 324 ETs 72 to 76 hours after insemination (day 3). The influence of the interval between insemination and ET was assessed, as well as that of the number of embryos transferred, embryo quality, and the presence of supernumerary embryos. The mean number of embryos transferred after 2 and 3 days was equal (2.9 embryos/ET). The pregnancy rates per ET were not significantly different (21.9% versus 23.5%), but a higher percentage of viable pregnancies was observed after ET on day 3 (88.2% against 69.5% following ET on day 2). Treatment outcome was positively correlated with the number of embryos transferred and the presence of supernumerary embryos.
Fertility and Sterility | 1985
Robert A. Leerentveld; Imprinetta van Gent; Marien van der Stoep; Juriy W. Wladimiroff
Growth of the dominant follicle was assessed by means of real-time sector scanning in 52 clomiphene citrate-stimulated cycles in 44 patients awaiting laparoscopic oocyte recovery for in vitro fertilization purposes. Follicular growth profiles under both monofollicular and multifollicular conditions were compared with each other and with a reference growth curve derived from 26 ovulatory cycles in 25 spontaneously cycling women. In the clomiphene-stimulated cycles, growth of the dominant follicle under both monofollicular and multifollicular conditions was significantly faster (P less than 0.01) than in the reference group. There was no significant difference in follicular growth between monofollicular and multifollicular clomiphene-stimulated cycles.
Fertility and Sterility | 1992
Gerritdina J. Huisman; Nadia M. Lo-A-Njoe; Albert Th. Alberda; Robert A. Leerentveld; Arie Verhoeff; Gerard H. Zeilmaker
A prospective controlled study was performed to compare the PRs obtained after use of a uniform IVF culture medium containing a pasteurized serum protein solution or patient serum. The ongoing PRs per ET in the serum and the protein solution group were 32% and 28%, respectively (not significant). Culture of supernumerary embryos showed blastocyst formation and even hatching with both supplements. The PR will not drop when this protein solution is used as a protein supplement in IVF culture medium instead of patient serum.
Ultrasound in Medicine and Biology | 1983
Robert A. Leerentveld; I. van Gent; A.Th. Alberda; Juriy W. Wladimiroff
Fifty clomiphene/H.C.G. stimulated patients undergoing laparoscopy as part of their infertility work up consented to participate in a study on: the reproducibility of ultrasonic measurement of follicular size as expressed by the inter and intra observer variation; the accuracy of ultrasonic assessment of location, number and size of follicles and the growth rate of the Graafian follicle during the last 12 hr prior to oocyte collection. The inter and intra observer variation was moderate to good. Correct diagnosis of the dominant follicle was made in 73%, of the number of follicles in 72% and of follicular size (difference in size between ultrasound and laparoscopy less than 2 mm) in 48% of the material studied. There was a rather wide range in follicular growth rate values during the last 10-17 hr prior to laparoscopy.
Human Reproduction | 1987
Robert A. Leerentveld; Gerard H. Zeilmaker; M. van der Stoep; Juriy W. Wladimiroff; F.H. de Jong; A.Th. Alberda
In 57 in-vitro fertilization (IVF) cycles stimulated with clomiphene citrate the relationship between plasma 17 beta-oestradiol (E2) and ultrasonographic measurements of follicle diameter was assessed. Under both monofollicular and multifollicular conditions a wide range in plasma E2 values was observed in the late follicular phase. No significant correlation could be established between the dimensions of the dominant preovulatory follicle and plasma E2 values, in mono-follicular or multi-follicular cycles. Pregnancies and conceptions occurred in cycles with both low and high circulating E2 levels. In pregnancy cycles a slight increase in plasma E2 values was found on the day following administration of human chorionic gonadotrophin (HCG). In conceptional cycles not leading to a clinical pregnancy, plasma E2 profiles varied considerably, whereas in cycles in which no oocytes were fertilized, plateauing or a distinct decrease occurred during this particular period. The present study suggests that the relative daily increase in plasma E2 values may be the most relevant aspect of plasma E2 monitoring.
Human Reproduction | 1992
H.C. van Os; Brigitte J. Roozenburg; H.A.B. Janssen-Caspers; Robert A. Leerentveld; Michael C.W. Scholtes; Gerard H. Zeilmaker; A.Th. Alberda
Human Reproduction | 1988
Robert A. Leerentveld; H.A.B. Janssen-Caspers; H.C. van Os; Michael C.W. Scholtes; Juriy W. Wladimiroff; Gerard H. Zeilmaker; F.H. de Jong; A.Th. Alberda
Human Reproduction | 1988
Michael C.W. Scholtes; W.C.J. Hop; A.Th. Alberda; H.A.B. Janssen-Caspers; Robert A. Leerentveld; H.C. van Os; Gerard H. Zeilmaker