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Biomedical subjects

William Shu Biu Yeung

Publications and source records attributed to William Shu Biu Yeung.

At least 19 recordsLinked to original sources
PubMed2006

Endometrial and subendometrial vascularity is higher in pregnant patients with livebirth following ART than in those who suffer a miscarriage.

BACKGROUND: Blood flow towards the peri-implantation endometrium may have effects on miscarriage and live birth following assisted reproduction treatment, in addition to its role in implantation. METHODS: Three-dimensional ultrasound examination with power Doppler was performed on the day of oocyte retrieval in stimulated IVF cycles and on LH + 1 day in frozen thawed-embryo transfer (FET) cycles to measure endometrial thickness, endometrial pattern, uterine artery Doppler flow indices, endometrial volume, vascularization index (VI), flow index (FI), vascularization flow index (VFI) of endometrial and subendometrial regions. RESULTS: In stimulated IVF cycles, 45 (28.0%) out of 161 pregnant patients subsequently miscarried. Patients in the live birth group had significantly higher endometrial VI and VFI and subendometrial VI, FI and VFI, when compared with those in the miscarriage group. In a multiple logistic regression analysis, only endometrial VI was significantly associated with the chance of live birth with an odds ratio of 1.384 [95% confidence interval (CI) 1.025-1.869, P = 0.034]. For FET cycles, patients in the live birth group had significantly higher endometrial VFI, subendometrial VI and VFI than those in the miscarriage group. CONCLUSIONS: Endometrial and subendometrial vascularity was significantly higher in pregnant patients with live birth following stimulated IVF and FET treatment than in those who suffered a miscarriage.

Abortion, Spontaneous↗
PubMed2006

Perifollicular vascularity in poor ovarian responders during IVF.

BACKGROUND: Normal ovarian responders who have follicles with good vascularity shown by power Doppler scanning are associated with a better pregnancy rate following IVF treatment. This study evaluated the significance of perifollicular vascularity and follicular fluid hormonal profile in poor responders who developed < or = 3 dominant follicles. METHODS: Before oocyte retrieval, they underwent power Doppler examination for perifollicular vascularity. Patients who had all follicles with low-grade vascularity were classified as Group A, whereas those with at least one follicle with high-grade vascularity were Group B. Their follicular fluid concentrations of estradiol (E2), progesterone, HCG, vascular endothelial growth factor (VEGF) and inhibin B were measured. RESULTS: A total of 58 consecutive patients were recruited: 38 in Group A and 20 in Group B. Implantation rate, clinical pregnancy rate and follicular fluid hormonal concentrations were comparable for Groups A and B. Multiple pregnancy and live birth rates appeared higher, whereas miscarriage rate were lower in Group B than Group A, but these differences did not reach statistical significance. CONCLUSION: There were no significant differences in the implantation, clinical pregnancy and live birth rates among poor responders with and without high-grade perifollicular vascularity.

Abortion, Spontaneous↗
PubMed2006

The role of endometrial and subendometrial vascularity measured by three-dimensional power Doppler ultrasound in the prediction of pregnancy during frozen-thawed embryo transfer cycles.

BACKGROUND: A good blood supply to the endometrium is usually considered as an essential requirement for implantation. OBJECTIVE: The aim of this study was to evaluate the role of endometrial and subendometrial vascularity in the prediction of pregnancy during frozen-thawed embryo transfer (FET) cycles. METHODS: Women undergoing FET in natural or clomiphene-induced cycles after the first stimulated IVF treatment were recruited. A three-dimensional (3D) ultrasound examination with power Doppler was performed 1 day after the LH surge to determine endometrial thickness, endometrial pattern, pulsatility index (PI) and resistance index (RI) of uterine vessels, endometrial volume, vascularization index, flow index and vascularization flow index of endometrial and subendometrial regions. RESULTS: Women in the pregnant group were significantly younger and used less gonadotrophins in their stimulated cycle. Endometrial thickness, endometrial volume, endometrial pattern, uterine PI, uterine RI, endometrial and subendometrial 3D power Doppler flow indices were similar between the nonpregnant and the pregnant groups. The age of women was the only predictive factor for pregnancy. Receiver operating characteristic curve analysis revealed that the area under the curve was around 0.5 for all ultrasound parameters for endometrial receptivity. CONCLUSION: Vascularity of endometrial and subendometrial layers measured by 3D power Doppler ultrasound is not a good predictor of pregnancy in FET cycles if measured at one time point only.

Adult↗
PubMed2005

Factors affecting endometrial and subendometrial blood flow measured by three-dimensional power Doppler ultrasound during IVF treatment.

BACKGROUND: No information exists in the literature regarding the factors affecting the blood flow towards the endometrial and subendometrial regions during IVF treatment. METHODS: We examined the effect of women's age, their smoking habits, their type of infertility (i.e. primary or secondary) and parity, causes of infertility and serum estradiol (E2) concentration on endometrial and subendometrial blood flows as measured by a three-dimensional (3D) power Doppler ultrasound during IVF treatment. All patients received a standard long protocol of ovarian stimulation and serum E2 concentration was determined on the day of hCG. 3D ultrasound examination with power Doppler was performed on the day of oocyte collection to determine vascularization index (VI), flow index (FI) and vascularization flow index (VFI) of endometrial and subendometrial regions. RESULTS: The age of women, their smoking habits, their types of infertility and parity and causes of infertility had no effect on the endometrial and subendometrial 3D power Doppler flow indices. There was a negative correlation between serum E(2) concentration and endometrial FI (r = -0.109; P = 0.006). CONCLUSIONS: Endometrial blood flow in IVF treatment was negatively affected by serum E2 concentration only.

Adult↗
PubMed2005

The role of endometrial and subendometrial blood flows measured by three-dimensional power Doppler ultrasound in the prediction of pregnancy during IVF treatment.

BACKGROUND: A good blood supply towards the endometrium is usually considered to be an essential requirement for implantation. We aimed to evaluate the role of endometrial and subendometrial blood flows in the prediction of pregnancy during IVF treatment. METHODS: Patients undergoing the first IVF cycle were recruited. A three-dimensional (3D) ultrasound examination with power Doppler was performed on the day of oocyte retrieval to determine endometrial thickness, endometrial pattern, pulsatility index (PI) and resistance index (RI) of uterine vessels, endometrial volume, vascularization index (VI), flow index (FI) and vascularization flow index (VFI) of endometrial and subendometrial regions. RESULTS: Uterine RI, endometrial VI and VFI were significantly lower in the pregnant group than the non-pregnant group. There was a non-significant trend of higher implantation and pregnancy rates in patients with absent endometrial or subendometrial blood flow. The number of embryos replaced and endometrial VI were the only two predictive factors for pregnancy. Receiver operator characteristic curve analysis revealed that the area under the curve was approximately 0.5 for all ultrasound parameters for endometrial receptivity. CONCLUSION: Endometrial and subendometrial blood flows measured by 3D power Doppler ultrasound were not good predictors of pregnancy if they were measured at one time-point during IVF treatment.

Adult↗
PubMed2005

Comparison of ovarian stromal blood flow between fertile women with normal ovaries and infertile women with polycystic ovary syndrome.

BACKGROUND: Conflicting information exists in the literature with respect to ovarian stromal blood flow in women with polycystic ovary syndrome (PCOS). We compared the ovarian stromal blood flow and serum vascular endothelial growth factor (VEGF) concentration between fertile women with normal ovaries and infertile women with PCOS. METHODS: In the second to fourth day of the menstrual period, they underwent transvaginal scanning with three-dimensional (3D) power Doppler to determine total antral follicle count (AFC), total ovarian volume, total ovarian vascularization index (VI), flow index (VFI) and vascularization flow index (VFI). Serum FSH, LH and VEGF concentrations were also checked. RESULTS: 107 fertile controls and 32 PCOS women were recruited. Fertile controls and PCOS women had similar total ovarian VI/FI/VFI after controlling for age of the woman, although PCOS women had significantly higher total AFC, total ovarian volume and serum LH concentration than fertile controls. Total ovarian VI/FI/VFI were significantly higher in normal weight (BMI < 25 kg/m2) PCOS women than their overweight (> or = 25 kg/m2) counterparts. CONCLUSIONS: Fertile controls and PCOS women had similar total ovarian 3D power Doppler flow indices. Normal weight PCOS women had significantly higher total ovarian 3D power Doppler flow indices than their overweight counterparts.

Adult↗
PubMed2005

A randomized double-blind controlled study of the efficacy of laser-assisted hatching on implantation and pregnancy rates of frozen-thawed embryo transfer at the cleavage stage.

BACKGROUND: Assisted hatching (AH) in fresh embryo transfer (ET) cycles increases the implantation and pregnancy rates, especially in women with a poor prognosis, repeated implantation failures and in older women. Little information exists in the literature regarding the role of AH in frozen-thawed embryo transfer (FET) cycles. METHODS: Embryos were cryopreserved at the cleavage stage. On the day of FET, 160 patients were randomized according to a computer-generated randomization list in sealed envelopes into the AH group and the control group. The patients and the clinicians were blinded to the group assigned. In the AH group, the outer half of the zona pellucida over a quarter of the diameter of zona was removed using a 1480 nm non-contact laser. RESULTS: The two groups were comparable in terms of demographic characteristics, ovarian response of the stimulated cycle and quality of fresh and frozen-thawed embryos. No differences in implantation, pregnancy and multiple pregnancy rates were found between the two groups. There was a non-significant trend of a higher implantation rate in the AH group when the zona thickness was > or = 16 mm. CONCLUSION: Laser AH did not improve the implantation rate of FET cycles and should not be performed routinely in all frozen-thawed embryos at the cleavage stage.

Adult↗
PubMed2005

Maternal serum pregnancy-associated plasma protein-A and free beta-human chorionic gonadotrophin in pregnancies conceived with fresh and frozen-thawed embryos from in vitro fertilization and intracytoplasmic sperm injection.

OBJECTIVE: Maternal serum pregnancy-associated plasma protein-A (PAPP-A) and free beta-human chorionic gonadotrophin (beta-hCG) are useful markers in the screening of Down syndrome in the first trimester. We investigated the effect of intracytoplasmic sperm injection (ICSI), freezing and thawing of embryos on the levels of these two analytes in assisted reproduction pregnancies. METHODS: We recruited 149 women who conceived after assisted reproduction with fresh embryos (92 from conventional IVF and 57 from ICSI), 85 women who conceived with frozen-thawed embryos (54 from conventional IVF and 31 from ICSI) and 401 women with spontaneous conceptions as controls. The concentrations of PAPP-A and free beta-hCG were measured between 10 and 14 weeks and were converted to multiples of medians (MoM) for comparisons. RESULTS: Median PAPP-A MoMs were significantly reduced in ICSI pregnancies in the fresh and frozen-thawed embryo subgroups (0.70 and 0.66 MoM respectively) and in the IVF fresh embryo subgroups (0.83 MoM), as compared to controls (1.00 MoM). Free beta-hCG MoM was significantly reduced in the IVF fresh embryos subgroup (0.87 MoM), but not in the other three subgroups. CONCLUSION: Further studies for exploring the underlying pathophysiology and adjustment in the marker levels for screening of Down syndrome are warranted in pregnancies conceived after assisted reproduction.

Adult↗
PubMed2005

The significance of antral follicle count in controlled ovarian stimulation and intrauterine insemination.

PURPOSE: This retrospective study evaluated the role of antral follicle count (AFC) in predicting ovarian response and successful outcome of stimulated insemination cycles. METHODS: One-hundred and fifty infertile women with bilateral patent tubes receiving a standard regime of human menopausal gonadotrophin (HMG) in their first cycle were evaluated. Multiple regression analysis was used to evaluate the effects of different parameters on ovarian responses and multiple logistic regression analysis was applied to determine which parameters gave the maximum discrimination to predict clinical pregnancy. RESULTS: Body mass index was the only significant parameter to predict the number of follicles > or =14 mm whereas AFC was the only significant parameter to predict the HMG duration. Only the number of follicles > or =14 mm significantly improved the chance of clinical pregnancy with an odds ratio of 1.8. CONCLUSION: AFC was related to the HMG duration but was not predictive of number of follicles and clinical pregnancy of stimulated insemination cycles.

Adult↗
PubMed2004

Endometrial and subendometrial blood flow measured by three-dimensional power Doppler ultrasound in patients with small intramural uterine fibroids during IVF treatment.

BACKGROUND: The impact of intramural fibroids on the success of IVF treatment is controversial and the mechanisms leading to poor treatment outcomes remain unknown. We compared endometrial and subendometrial blood flow between women with and without intramural fibroids during IVF treatment. METHODS: Three-dimensional (3D) ultrasound examination with power Doppler was performed on the day of oocyte retrieval in 50 patients with intramural fibroids not distorting the uterine cavity and in 50 matched controls to measure endometrial thickness, uterine pulsatility index (PI)/resistance index (RI), endometrial volume and vascularization index (VI)/flow index (FI)/vascularization flow index (VFI) of endometrial and subendometrial regions. Smokers, patients with serum estradiol concentrations > or =20,000 pmol/l on the day of HCG and previous history of myomectomy were excluded. RESULTS: Endometrial thickness and pattern, averaged uterine PI and RI and endometrial and subendometrial VI/FI/VFI were similar between the fibroid group and the control group. There was no correlation between the total volume of fibroids and endometrial and subendometrial 3D power Doppler flow indices in the fibroid group. CONCLUSION: Endometrial and subendometrial 3D power Doppler flow indices were similar in patients with and without small intramural fibroids.

Adult↗
PubMed2004

Effect of pituitary downregulation on antral follicle count, ovarian volume and stromal blood flow measured by three-dimensional ultrasound with power Doppler prior to ovarian stimulation.

BACKGROUND: Despite the extensive use of gonadotrophin releasing hormone agonists (GnRH ag) for pituitary downregulation, the literature regarding their effect on ultrasound parameters for predicting ovarian responses are few and conflicting. The aim of this prospective study was to compare antral follicle count (AFC), ovarian volume and ovarian stromal blood flow measured by three-dimensional (3D) power Doppler ultrasound before and after pituitary downregulation. METHODS: All patients received a long protocol of intranasal Buserelin from the mid-luteal phase of the cycle. In the early follicular phase of the preceding cycle before downregulation and on the second day of the treatment cycle after downregulation, patients underwent a blood test for serum FSH, LH and estradiol and a transvaginal scanning with 3D power Doppler to determine AFC, ovarian volume and ovarian 3D power Doppler flow indices. RESULTS: Out of 104 women scanned, 85 women were analysed. Polycystic ovaries were encountered in 14 (16.5%) women. No significant differences in any of the ultrasound parameters were demonstrated before and after downregulation, in patients with normal ovaries or in those with polycystic ovaries. CONCLUSION: AFC, ovarian volume and ovarian 3D power Doppler flow indices did not significantly change after a short-term treatment of GnRH agonist for pituitary downregulation.

Adult↗
PubMed2004

Comparison of endometrial and subendometrial blood flow measured by three-dimensional power Doppler ultrasound between stimulated and natural cycles in the same patients.

BACKGROUND: Low implantation rates in stimulated IVF cycles may be related to suboptimal endometrial perfusion. Endometrial and subendometrial blood flow was compared between stimulated and natural cycles in the same patients undergoing IVF. METHODS: Three-dimensional (3D) ultrasound examination with power Doppler was performed in stimulated and natural cycles of 67 consecutive patients to measure endometrial thickness, uterine artery pulsatility index/resistance index, endometrial volume, vascularization index (VI)/flow index (FI)/vascularization flow index (VFI) of endometrial and subendometrial regions. RESULTS: Endometrial and subendometrial blood flow was absent in four (6.0%) patients in the stimulated cycle and two (3.0%) patients in the natural cycle. Endometrial and subendometrial VI/FI/VFI were significantly lower in stimulated cycles than those in natural cycles. The median (95% CI) decreases in endometrial VI/FI/VFI were 35.8% (-2.5, 216.8), 5.0% (0.1, 12.3) and 48.4% (2.5, 315.3) respectively whereas the corresponding decreases in the subendometrial region were 66.6% (-0.2, 220.5), 4.3% (0.8, 16.2) and 76.3% (41.0, 303.4) respectively. CONCLUSION: Endometrial and subendometrial blood flow was significantly lower in the stimulated cycle than that in the natural cycle.

Adult↗
PubMed2004

Effect of age on ovarian stromal flow measured by three-dimensional ultrasound with power Doppler in Chinese women with proven fertility.

BACKGROUND: Increasing age is associated with reduced ovarian stromal blood flow detected by three-dimensional (3D) power Doppler ultrasound in infertile patients. However, little information exists in the literature regarding the effect of age on the ovarian stromal blood flow in fertile women. METHODS: On the second to fourth day of their menstrual cycle, fertile Chinese women who had regular monthly cycles and no history of tubal and ovarian surgery underwent a transvaginal scan with 3D power Doppler to determine total antral follicle count (AFC), total ovarian volume, total ovarian vascularization index (VI)/flow index (FI)/vascularization flow index (VFI). Serum FSH and vascular endothelial growth factor concentrations were checked. RESULTS: Out of 177 women scanned, 138 women were included in the final analysis. Total AFC and serum FSH were significantly different among four age groups (< or = 30, 31-35, 36-40 and > or = 41 years). Total ovarian VI and VFI were significantly lower in women aged > or = 41 years. AFC had the best correlation with the age of women, followed by serum FSH concentration and ovarian 3D power Doppler indices. The rate of decline of total ovarian VI was 0.18% per year. CONCLUSION: Ovarian stromal blood flow was significantly reduced only in women aged > or = 41 years.

Adult↗
PubMed2004

Concentrations of endometrial protein PP 14 and CA-125 in uterine flushings performed in natural and stimulated cycles.

BACKGROUND: Impaired implantation in assisted reproduction cycles with high serum estradiol (E(2)) concentrations may be attributed to abnormal endometrial development. This study compared concentrations of endometrial proteins in uterine flushings of infertile patients between natural and stimulated cycles. METHODS: Patients received a standard regimen of ovarian stimulation. Seven days after the LH surge in natural cycles or the hCG injection in stimulated cycles, uterine flushings were performed by slowly injecting and aspirating normal saline through a paediatric Foley catheter. Natural cycles were considered as group A whereas stimulated cycles with serum E(2) <20 000 pmol/l and serum E(2) >20 000 pmol/l were classified as groups B and C respectively. PP 14 and CA-125 in uterine flushings were measured and expressed per total protein content. RESULTS: Concentrations of the total protein, PP 14 and CA-125 in the uterine flushings were similar among the three groups. PP 14 per total protein in the uterine flushings was significantly correlated with serum E(2) on the day of hCG (r = 0.459; P = 0.009) in natural cycles only but not in stimulated cycles. CONCLUSION: There was no significant difference between natural and stimulated cycles in concentrations of PP 14 and CA-125 in uterine flushings performed in the mid-luteal phase.

Adult↗
PubMed2004

Endometrial and subendometrial blood flow measured during early luteal phase by three-dimensional power Doppler ultrasound in excessive ovarian responders.

BACKGROUND: Impaired implantation in assisted reproduction cycles with high serum estradiol (E(2)) concentrations may be related to suboptimal endometrial perfusion. Endometrial and subendometrial blood flow were compared between excessive responders (serum E(2) on the day of HCG >20 000 pmol/l) and moderate responders (E(2) < or =20 000 pmol/l). METHODS: Three-dimensional (3D) ultrasound examination with power Doppler was performed 2, 4 and 7 days after HCG in 32 patients who did not have embryo transfer in order to measure endometrial thickness, pulsatility index (PI)/resistance index (RI) of uterine vessels, and endometrial volume, vascularization index (VI)/flow index (FI)/vascularization flow index (VFI) of endometrial and subendometrial regions. RESULTS: Excessive responders tended to have lower endometrial and subendometrial VI/VFI on HCG +2 and more absent endometrial/subendometrial blood flow. They had significantly higher endometrial FI and subendometrial VFI than moderate responders on HCG +7. Only in the excessive responder group, uterine PI/RI declined significantly from HCG +2 to HCG +7 and endometrial VI/VFI increased significantly from HCG +4 to HCG +7. CONCLUSION: Changes in uterine Doppler flow indices, and endometrial and subendometrial 3D power Doppler flow indices during the early luteal phase were significantly different between moderate and excessive responders.

Adult↗
PubMed2003

Is there any difference in pregnancy and implantation rates when nurses perform embryo transfer in an IVF-ET program?

A retrospective analysis of fresh in vitro fertilization treatment cycles and frozen embryo transfer (FET) cycles from mid-1995 to December 31, 1998, was undertaken. Nurses performed embryo transfer (ET) for government-funded cycles, whereas doctors performed ET for self-funded cycles. During the study period, fresh ET was performed in 1,165 treatment cycles. There were no significant differences in demographic data, ovarian responses and the number of embryos replaced between ET cycles performed by nurses and doctors. Pregnancy rates for ETs performed by nurses and doctors were 16.7 and 15.8% per transfer, respectively, whereas the corresponding implantation rates were 8.3 and 6.9%, respectively. Similar pregnancy and implantation rates were encountered in FET cycles whether ET was performed by nurses or doctors.

Adult↗
PubMed2003

Oocyte and embryo quality in patients with excessive ovarian response during in vitro fertilization treatment.

PURPOSE: This study examined oocyte and embryo quality in patients having excessive ovarian responses during assisted reproduction treatment. METHODS: Two hundred and seventy-eight women of age <40 years using a long protocol of pituitary downregulation in their first intracytoplasmic sperm injection cycle indicated for severe male factors were retrospectively evaluated. Those with serum estradiol concentration on the day of HCG <10,000, 10,000-20,000, and >20,000 pmol/L were classified into Group A, Group B, and Group C, respectively. RESULTS: The percentage of metaphase II oocytes (85%), fertilization rate (60-66%), and distribution of blastomere number per embryo were similar among the three groups. The proportion of transferable embryos was not reduced in Group C when compared to those of Groups A and B. CONCLUSION: Excessive ovarian response does not compromise oocyte and embryo quality in humans. Freezing of all embryos is recommended in these patients in view of associated impaired endometrial receptivity.

Adult↗