84 Effect of Embryo Stage and Cryopreservation Method on Pregnancy Rates Obtained Following the Transfer of In Vivo-Derived Ovine Embryos on Small-Scale Farms in Thailand

2018 ◽  
Vol 30 (1) ◽  
pp. 181
Author(s):  
S. Khunmanee ◽  
J. Suwimonteerabutr ◽  
M. Techakumphu ◽  
T. Swangchan-Uthai
Keyword(s):  
Pregnancy Rate ◽  
Embryo Transfer ◽  
Blastocyst Stage ◽  
Pregnancy Rates ◽  
Slow Freezing ◽  
Small Scale ◽  
Tropical Conditions ◽  
Frozen Embryos ◽  
Embryo Stage ◽  
Cryopreservation Method

Assisted reproductive technologies including superovulation, laparoscopic AI (LAI), and embryo transfer (ET) are important tools for genetic improvement in the sheep industry. The present study aimed to determine the effects of embryo stage and cryopreservation method on field trial outcomes of embryo transfer on small-scale farms in Thailand. Black Dorper ewes (n = 16) were used as donors and mixed breed ewes (n = 21) were used as recipients. Donors were superovulated as previously described (Tríbulo et al. 2012 Theriogenology 77, 1679-1685, 10.1016/j.theriogenology.2011.12.013) and inseminated by LAI within 22 to 24 h after standing heat (Day 0). Donors females were flushed on Day 2 to recover 2- to 8-cell embryos (n = 8) or on Day 6 to recover blastocyst-stage embryos (n = 8). Recovered embryos were randomly cryopreserved by either slow freezing or vitrification methods. Into 21 recipients was inserted an intravaginal device impregnated with CIDR® that was left in place for 10 days. Those received 300 IU of pregnant mare serum gonadotropin (PMSG) on Day 9 and randomly assigned to receive embryos on either Day 2 or 6 after oestrus. Two- to 8-cell embryos were thawed and transferred into the ipsilateral oviduct (n = 1-5 embryos/recipient) on Day 2. Five recipients received 15 slow-frozen embryos and 5 received 13 vitrified embryos. Blastocyst stage embryos were thawed and transferred into the ipsilateral uterine horn (n = 1-4 embryos/recipient) on Day 6. Five recipients received 11 slow-frozen embryos and 4 received 7 embryos. Pregnancy diagnosis was determined by ultrasonography 45 days after embryo transfer. Pregnancy rate was calculated as the proportion of ewes with at least one pregnancy out of the total number of ewes that received embryos. Chi-squared analysis was used to determine the effects of embryo freezing technique and embryo stage on pregnancy rate (SAS 9.2, SAS Institute Inc., Cary, NC, USA). All donor ewes responded to the superovulation program (donor had 3 to 6 corpora lutea). The mean number of viable embryos recovered was 4.3 ± 2.4 and 3.1 ± 3.7 for Day 2 and Day 6, respectively. Nineteen of the 21 recipient ewes responded to the synchronization program and received embryos in the study. There was no effect (P > 0.05) of embryo stage (5/10 = 50% v. 3/9 = 33.3% for 2- to 8-cell v. blastocyst, respectively) or cryopreservation method (4/10 = 40% v. 4/9 = 44.4% for slow-freezing and vitrification, respectively) on pregnancy rate following embryo transfer. Results of the present study suggest that similar pregnancy rates following embryo transfer in sheep under tropical conditions in Thailand can be obtained using either 2- to 8-cell embryos or blastocyst-stage embryos and with embryos that have been cryopreserved by slow-freezing or vitrification. Further research with larger numbers of animals is necessary to confirm the preliminary results of the present study.

37 EFFECT OF EMBRYO STAGE ON PREGNANCY RATE FOLLOWING DIRECT TRANSFER OF BOVINE EMBRYOS FROZEN IN ETHYLENE GLYCOL

2012 ◽  
Vol 24 (1) ◽  
pp. 131 ◽  
Author(s):  
J. F. Hasler
Keyword(s):  
Ethylene Glycol ◽  
Pregnancy Rate ◽  
Embryo Transfer ◽  
The United States ◽  
Pregnancy Rates ◽  
Bovine Embryos ◽  
Embryo Freezing ◽  
Percentage Points ◽  
Embryo Stage

Annually, more than 400 000 in vivo-recovered bovine embryos are officially reported by members of the Canadian and American Embryo Transfer Associations. Between 65 and 70% of these embryos are cryopreserved and more than 95% are frozen in ethylene glycol (EG). Statistics on factors affecting embryo freezing are difficult to obtain because many cattle breeders/farmers no longer report pregnancy rates back to embryo transfer (ET) practitioners. Concerns are often expressed as to the optimal stage at which to freeze bovine in vivo-derived embryos. This is a retrospective analysis of results from 5 commercial ET programs (1 in the United States, 3 in Canada and 1 in the Netherlands) for which pregnancy data relative to embryo stage at freezing were made available. Embryos representing 4 stages of development, as defined by the IETS (4 = late morula, 5 = early blastocyst, 6 = mid blastocyst and 7 = expanded blastocyst) are included in the data. The number of embryos thawed and transferred ranged from 3954 to 24 827 for the 5 programs, with a total of 72 828. Embryos were frozen in either 1.5 M EG or 1.5 M EG + 0.1 M sucrose and exposure time to cryoprotectant before cooling ranged from 4 to 40 min. Pregnancy rates are shown in Table 1. Although the pregnancy rate for stage 6 embryos was only 2.6 and 3.2 percentage points lower than stages 4 and 5, respectively, these differences were highly significant and pregnancy rates for stage 6 embryos were lower than those for stages 4 and 5 in 4 of the 5 ET programs. The small decreased survival of stage 6 embryos is probably only moderately important in a commercial context. However, the pregnancy rate of stage 7 embryos was lower than all other stages for the combined dataset as well as in all 5 ET programs, with the difference between stages 5 and 7 ranging from 6.5 to 16.4 percentage points. Clearly, stage 7 embryos survive freezing at a significantly lower rate than stages 4, 5 and 6 and neither time of exposure to EG nor inclusion of sucrose in the freezing medium provided an obvious improvement. Although bovine ET practitioners routinely attempt to collect embryos on day 7 post-oestrus, recovery of stage 7 embryos cannot always be avoided. Further investigation into factors contributing to the decreased survival of stage 7 embryos is warranted. Table 1.Effect of embryo stage on pregnancy rate of bovine embryos frozen in EG

scholarly journals 168FACTORS AFFECTING ON EMBRYO TRANSFER PREGNANCY RATES OF IN VITRO-PRODUCED BOVINE EMBRYOS

2004 ◽  
Vol 16 (2) ◽  
pp. 206 ◽  
Author(s):  
S. Aoki ◽  
S. Murano ◽  
M. Miyamura ◽  
S. Hamano ◽  
Y. Terawaki ◽  
...  
Keyword(s):  
Pregnancy Rate ◽  
Estrous Cycle ◽  
Embryo Transfer ◽  
Calf Serum ◽  
Pregnancy Rates ◽  
Factors Affecting ◽  
Frozen Embryos ◽  
Rectal Palpation ◽  
Day Of Embryo Transfer

The objective of this study was to analyze factors affecting the pregnancy rates after transfer of IVF-derived Japanese Black embryos. Holstein cows and heifers (n=7250) were selected as recipients, and embryo transfers were performed for 3yr (between 1998 and 2000). The IVM-IVF procedure was performed according to a method previously described (Hamano S and Kuwayama M 1993 Theriogenology 39, 703–712). IVF-derived embryos that developed into expanded blastocysts (grade 1, manual of IETS) after 7 to 8 days (insemination=Day 0) were used for this study. Some of these embryos were frozen in TCM-199 supplemented with 1.4M glycerol, 20% calf serum, and 0.25M sucrose. The embryos were seeded at −6°C, held at −6°C for 10min, and then cooled to −25°C at a rate of 0.33°Cmin−1. Frozen embryos were thawed in a 30 to 35°C water bath after 10s of air thawing. Fresh (n=3952) or frozen-thawed (n=3298) embryos were nonsurgically transferred to recipients on Days 6 to 9 of the estrous cycle. Data collected at the time of embryo transfer included recipient parity (cow or heifer), whether recipient estrus was natural or synchronized with PGF2α, cloprostenol or CIDR, methods of estrous confirmation (showing standing heat, rectal palpation of ovary without standing heat, or showing only mucous vulvular discharge), number of examinations of the CL by palpation per rectum (twice on the day before embryo transfer and the day of embryo transfer, or once on the day of embryo transfer), type of embryos (fresh or frozen), and day of the estrous cycle at the time of embryo transfer. CATMOD procedures of SAS were used to determine the factors affecting the pregnancy rate. Overall pregnancy rates were 37.3% (n=2704). Whether recipient estrus was natural or synchronized and the type of embryos did not influence the pregnancy rates. Heifers had significantly higher pregnancy rates than cows (44.0% v. 33.0%, respectively, P<0.05). Pregnancy rates among the subset of heifers and cows showing standing heat were significantly higher than those showing only mucous vulvular discharge (39.5% v. 33.5%, respectively, P<0.05). Examining the CL twive had a significantly higher pregnancy rate than did a single examination of the CL (41.1% v. 35.6%, respectively, P<0.05). Pregnancy rate on Day 8 (38.4%, 1358/3533) of the estrous cycle at the time of embryo transfer was significantly higher than on Days 6 (27.7%, 23/83) and 7 (36.2%, 1235/3408) (P<0.05), and the pregnancy rate on Day 6 of the estrous cycle at the time of embryo transfer tended to be lower than on Day 9 (38.9%, 88/226) (P<0.08). These results demonstrate that confirming standing heat, performing CL examination twice before embryo transfer, freezing high quality embryos, and performing embryo transfers on Day 8 resulted in an improved pregnancy rate for the transfer of IVF-derived embryos.

scholarly journals Factors associated with pregnancy rate in fixed-time embryo transfer in cattle under humid-tropical conditions of México

2020 ◽  
Vol 17 (2) ◽  
Author(s):  
Alfonso Pérez-Mora ◽  
José Candelario Segura-Correa ◽  
Jorge Alonso Peralta-Torres
Keyword(s):  
Pregnancy Rate ◽  
Embryo Transfer ◽  
Fixed Time ◽  
Factors Associated ◽  
Tropical Conditions

scholarly journals The effect of low-dose aspirin on the pregnancy rate in frozen-thawed embryo transfer cycles: A randomized clinical trial

2020 ◽  
Author(s):  
Robab Davar ◽  
Soheila Pourmasumi ◽  
Banafsheh Mohammadi ◽  
Maryam Mortazavi Lahijani
Keyword(s):  
Clinical Trial ◽  
Pregnancy Rate ◽  
Embryo Transfer ◽  
Low Dose ◽  
Endometrial Thickness ◽  
Pregnancy Rates ◽  
Clinical Pregnancy ◽  
Dose Aspirin ◽  
Low Dose Aspirin ◽  
Clinical Pregnancy Rates

Background: The results of previous studies on the effect of low-dose aspirin in frozenthawed embryo transfer (FET) cycles are limited and controversial. Objective: To evaluate the effect of low-dose aspirin on the clinical pregnancy in the FET cycles. Materials and Methods: This study was performed as a randomized clinical trial from May 2018 to February 2019; 128 women who were candidates for the FET were randomly assigned to two groups receiving either 80 mg oral aspirin (n = 64) or no treatment. The primary outcome was clinical pregnancy rate and secondary outcome measures were the implantation rate, miscarriage rate, and endometrial thickness. Results: The endometrial thickness was lower in patients who received aspirin in comparison to the control group. There were statistically significant differences between the two groups (p = 0.018). Chemical and clinical pregnancy rates and abortion rate was similar in the two groups and there was no statistically significant difference. Conclusion: The administration of aspirin in FET cycles had no positive effect on the implantation and the chemical and clinical pregnancy rates, which is in accordance with current Cochrane review that does not recommend aspirin administration as a routine in assisted reproductive technology cycles. Key words: Aspirin, Embryo transfer, Pregnancy rates.

P–159 Slow-growing embryos should be frozen on day 5

2021 ◽  
Vol 36 (Supplement_1) ◽  
Author(s):  
M J Zamora ◽  
I Katsouni ◽  
D Garcia ◽  
R Vassena ◽  
A Rodríguez
Keyword(s):  
Pregnancy Rate ◽  
Embryo Transfer ◽  
Live Birth ◽  
Birth Rate ◽  
Live Birth Rate ◽  
Study Groups ◽  
Pregnancy Rates ◽  
Clinical Pregnancy ◽  
Patient Counselling ◽  
Slow Growing

Abstract Study question What is the live birth rate after frozen embryo transfer (FET) of slow-growing embryos frozen on day 5 (D5) or on day 6 (D6)? Summary answer The live birth rate after single FET is significantly higher for slow-growing embryos frozen on D5 compared to those frozen on D6. What is known already Most data on the outcomes of blastocyst transfer stem from studies that evaluate fresh transfer from normal growing D5 blastocyst ET. However not all embryos will begin blastulation nor reach the fully expanded stage by D5; those are the slow-growing embryos. Studies that compare D5 to D6 embryos in FET cycles show contradictory results. Some have reported higher clinical pregnancy rates after D5 FET, while others have reported similar outcomes for D5 and D6 cryopreserved blastocyst transfers. There is a lack of evidence regarding the best approach for vitrifying embryos that exhibit a slow developmental kinetic. Study design, size, duration This retrospective cohort study included 821 single FET of slow-growing embryos frozen on D5 or D6, belonging to patients undergoing in vitro fertilization with donor oocytes between January 2011 and October 2019, in a single fertility center. The origin of blastocysts was either supernumerary embryos after fresh embryo transfer or blastocysts from freeze-all cycles. All embryos were transferred 2- 4h after thawing. Participants/materials, setting, methods We compared reproductive outcomes of slow-growing embryos frozen on D5 versus (n = 442) slow-growing embryos frozen on D6 (n = 379). D5 group consisted in embryos graded 0, 1, 2 of Gardner scale and frozen on D5. Similarly, D6 group consisted in embryos graded 3, 4, 5 of Gardner scale (blastocyst stage) and frozen on D6. Differences in pregnancy rates between study groups were compared using a Chi2 test. A p-value <0.05 was considered statistically significant. Main results and the role of chance Baseline characteristics were comparable between study groups. Overall, mean age of the woman was 42.3±5.4 years old; donor sperm was used in 25% of cycles, and it was frozen in 73.2% of cycles. Pregnancy rates were significantly higher when transferring slow D5 embryos compared to D6 for all the pregnancy outcomes analyzed: biochemical pregnancy rate was 27.7% vs 20.2%, p < 0.016; clinical pregnancy rate was 17.5% vs 10.2%, p < 0.004); ongoing pregnancy rate was: 15.7% vs 7.8% (p < 0.001); live birth rate was: 15.4% vs 7.5%, (p < 0.001). These results suggest that when embryos exhibit a slow development behavior (not reaching full blastocysts at D5), waiting until D6 for blastulation and expansion does not improve clinical outcomes. Vitrification at D5 will should the preferred option in cases where the oocyte is assumed of high quality Limitations, reasons for caution The retrospective design of the study is its main limitation. Also, morphology as sole selection criterion for transfer. However, blastocyst morphology is a very good predictor of implantation and pregnancy, and a good indicator of the embryo’s chromosomal status (higher euploidy rate in higher morphological quality blastocysts). Wider implications of the findings: These results can help to the standardization of laboratory protocols. As the decision of vitrifying slow developing embryos on D5 or D6 is made by the laboratory team or by the gynaecologist in agreement with the patient, having an evidence based strategy simplifies patient counselling and decision making. Trial registration number Not applicable

206 EFFECTS OF A COMBINATION OF A PRID, PGF2α AND eCG, ON ESTRUS SYNCHRONIZATION AND PREGNANCY RATE FOLLOWING EMBRYO TRANSFER IN HOLSTEIN HEIFERS

2007 ◽  
Vol 19 (1) ◽  
pp. 220 ◽  
Author(s):  
Y. Aoyagi ◽  
A. Ideta ◽  
M. Matsui ◽  
K. Hayama ◽  
M. Urakawa ◽  
...  
Keyword(s):  
Pregnancy Rate ◽  
Embryo Transfer ◽  
Plasma Concentrations ◽  
Pregnancy Rates ◽  
Bovine Embryo ◽  
Estrus Synchronization ◽  
Chi Square ◽  
End Of Treatment ◽  
Chi Square Analysis ◽  
Day Of Embryo Transfer

Successful bovine embryo transfer requires synchronization of luteolysis, estrus and ovulation. The objective of the present study was to evaluate the effect of a combination of a PRID, PGF2� and eCG, on estrus synchronization and pregnancy rate in recipient heifers. A PRID� (ASKA Pharmaceutical Co., Ltd., Tokyo, Japan) was inserted into the vagina at random days of the estrous cycle for 7 (n = 35) or 9 (n = 43) days. Two days before removal of the PRID, the heifers were injected with PGF2� IM (2 mL Resipron�-C containing 0.25 mg mL-1 cloprostenol; ASKA). About half of the heifers in each group received 250 IU eCG IM (Serotropin�; ASKA) at the time of PRID removal. Blood was collected several times from the start of treatment for 7 (n = 9) or 9 (n = 9) days and on the day of embryo transfer by jugular venipuncture; plasma was immediately separated and stored at -20�C until assayed for plasma concentrations of estradiol-17α (E2) and progesterone (P4). The E2 and P4 determinations were performed by enzyme immunoassay after extraction by diethyl ether. Pregnancy was determined by ultrasonography on Day 30 (Day 0 = estrus). The rates of successful standing estrus (no. in estrus/PRID inserted), embryo transfer (no. transferred/estrus), and pregnancy (no. pregnancy/transferred) were compared between groups. Data were analyzed by chi-square analysis or Fisher's PLSD test following ANOVA. Injection of eCG at the time of PRID removal had no significant effect on the rates of successful standing estrus, embryo transfer, or pregnancy (P > 0.05). The proportion of heifers treated for 9 days that exhibited standing estrus (93%, 40/43) was significantly higher than the proportion of heifers treated for 7 days that exhibited standing estrus (66%, 23/35, P < 0.01). Of the heifers that were treated for 9 days, the proportion of heifers exhibiting standing estrus within 2 days after the end of treatment was significantly higher (93%, 37/40) than for heifers that were treated for 7 days (65%, 15/23; P < 0.01). Pregnancy rates of heifers treated for 9 days (84%, 32/38) and 7 days (81%, 17/21) were not significantly different. The E2 : P4 ratio normally increases during follicle growth and CL regression. The plasma E2 : P4 ratio between the time of injection of PGF2α and the time of PRID removal was significantly higher for heifers that were treated for 9 days than it was for heifers that were treated for 7 days (P < 0.01). These results suggest that a combination of PRID treatment for 9 days and injection of PGF2α 2 days before PRID removal successfully synchronized estrus in recipient heifers and led to high pregnancy rates following embryo transfer.

191 INFLUENCE OF THE DIFFERENT TIME COMPONENTS BETWEEN FLUSHING AND TRANSFER ON PREGNANCY RATES OF FROZEN CATTLE EMBRYOS

2006 ◽  
Vol 18 (2) ◽  
pp. 203
Author(s):  
C. Ponsart ◽  
H. Quinton ◽  
A. Rohou ◽  
J. Kelhembo ◽  
G. Bourgoin ◽  
...  
Keyword(s):  
Pregnancy Rates ◽  
Chi Square ◽  
Frozen Embryos ◽  
Multivariate Logistic Model ◽  
Parity Number ◽  
Embryo Stage ◽  
Chi Square Analysis ◽  
Fresh Embryos ◽  
Donor Cows

Previous studies have shown that the time between flushing and freezing of bovine embryos can influence pregnancy rates (PRs) following embryo transfer (ET). The aim of this study was to determine which time components can influence ET results. Time components between flushing of a superovulated donor and freezing of the collected embryos were investigated under field conditions. Embryos were frozen in 1.5 M ethylene glycol (EG) for direct transfer. During January 2003, ET technicians (EmbryoTop, Rennes cedex, France) recorded systematically times corresponding to each step comprising the time spent in vitro (TIV) from 153 recovery sessions (RS) with freezing: end of flushing, beginning and end of search of embryos, start of equilibration in EG, beginning and end of straw loading, introduction to −7°C in the freezer, and seeding. Numbers of donor cows and ET technicians doing the freezing (n = 5) were noted for each RS. Embryo (stage, quality) and recipient (breed, parity) characteristics were also noted. A total of 548 frozen embryos were transferred and PRs were assessed. Variability of time components was investigated (Bourgoin et al. 2004 Reprod. Fertil. Dev. 16, 207). The influence of time components and other variation factors was tested on PRs (t-tests and chi-square analysis). The TIV averaged 210 ± 80 min and did not influence PR (≤4 h = 51.9% (n = 393) vs. >4 h = 55.5% (n = 155); P > 0.05), as well as duration of flushing (32 ± 8 min), interval between end of flushing and search (31 ± 27 min), duration of search (45 ± 25 min) and interval between end of search and beginning of freezing (101 ± 63 min). Only significant factors were kept for further analysis. The effects of recipient parity, number of donor cows per RS, and interval between introduction of straw to −7°C, and seeding were tested in a multivariate logistic model. PR varied strongly with parity of recipient (+25% in heifers vs. cows; P = 0.001). PRs were higher when the interval between straw introduction in the freezer and seeding lasted at least 5 min (2–4 min = 48.0% (n = 254) vs. 5–8 min = 57.1% (n = 294); P = 0.009). Time and operator effects were confounded. Overall PR results for the two technicians who used mostly 2–4 min intervals averaged 47% (operator values = 35.6, 48.9, and 54.5) whereas PRs were 54.9 and 60.5% for those waiting 5 min or more before inducing seeding (n = 2). PRs were higher when at least two donor cows were collected per RS (1 donor cow = 49% (n = 259) vs. ≥2 donor cows = 56.4% (n = 289); P = 0.003). This was not in agreement with previous observations in fresh embryos (Bourgoin et al. 2004). However, the number of donor cows strongly influenced the number of viable embryos per RS (1 donor cow = 11 ± 5 vs. ≥2 donor cows = 18 ± 8.5; P < 0.05) and could permit the choice of more embryos to be frozen. These results show that good PR may be achieved with a delay of several hours between flushing and freezing, when heifers are used as recipients. Moreover, confirmed from higher numbers of operators, these data show that it is better to wait at least 5 min to achieve equilibration of the embryo before seeding.

109 RELATIONSHIP BETWEEN ULTRASONIC MORPHOLOGY OF CORPUS LUTEUM IN HOLSTEIN HEIFERS AND PREGNANCY RATE AFTER EMBRYO TRANSFER

2012 ◽  
Vol 24 (1) ◽  
pp. 167
Author(s):  
A. Shirasawa ◽  
Y. Nakamura ◽  
A. Ideta ◽  
Y. Oono ◽  
M. Urakawa ◽  
...  
Keyword(s):  
Corpus Luteum ◽  
Pregnancy Rate ◽  
Embryo Transfer ◽  
Blood Clot ◽  
Pregnancy Rates ◽  
Bovine Embryo ◽  
Tissue Area ◽  
The Mean ◽  
Rectal Palpation ◽  
Experimental Group

Recipient animals for bovine embryo transfer (ET) are routinely selected according to the morphology of the corpus luteum (CL) estimated by rectal palpation. However, rectal palpation is not a precise method of diagnosing the functional status of a CL. Ovarian ultrasonography (US) may be used to improve such diagnoses. The aim of this study was to evaluate the relationship between ultrasonographic images of CL and pregnancy rates after ET in Holstein heifers to determine whether US can be used to select recipients for ET. Recipient heifers (n = 285) were selected by detection of natural oestrus or following oestrus synchronization using a progesterone-releasing intravaginal device (PRID; ASKA Pharmaceutical, Tokyo, Japan). Transrectal US was performed immediately before ET, on Days 6 to 8 of the oestrous cycle (oestrus = Day 0), using a B-mode scanner (HS1500V; Honda Electronics Co. LTD, Aichi, Japan) equipped with a 7.5-MHz linear-array transducer designed for intrarectal placement. A cross-sectional image of the maximal area of the CL and luteal cavity was obtained. The areas of the CL and luteal cavity were each calculated using the formula for the area of an ellipse (height/2 × width/2 × π). (1) Ultrasonic morphology of CL was classified into 3 types: without cavity (n = 128), with cavity (n = 145) and with blood clot (n = 12). (2) The luteal cavity was categorized into 3 groups: small (<100 mm2, n = 93), medium (100 ≤ x < 200 mm2, n = 32) and large (≥200 mm2, n = 20). (3) Luteinized tissue area (total area of CL minus the area of the luteal cavity) was categorized into 3 groups: small (<250 mm2, n = 61), medium (250 ≤ x < 350 mm2, n = 128) and large (≥350 mm2, n = 84). In vivo–produced embryos were transferred nonsurgically into the uterine horn ipsilateral to the CL. Pregnancy was determined by transrectal US on Days 30 to 40 of gestation. The pregnancy rates of each experimental group were analysed by logistic regression. In this study, the pregnancy rate did not differ significantly in each experimental group: (1) without cavity: 77.3% (99/128), with cavity: 75.2% (109/145) and blood clot: 75.0% (9/12); (2) small cavity: 73.1% (68/93), medium: 75.0% (24/32) and large: 85.0% (17/20). The mean area of the cavity was 100.8 ± 110.3 mm2 (mean ± standard deviation) and recipients with 0 to 539.7 mm2 sized cavities had successful pregnancies (observational range was 0 to 539.7 mm2). (3) The pregnancy rates of recipients that had small, medium and large luteinized tissue were 77.0% (47/61), 75.0% (96/128) and 77.4% (65/84), respectively. The mean area of luteinized tissue was 318.9 ± 90.3 mm2 and 155.0 to 620.0 mm2 sized luteinized tissue had pregnancy success (observational range was 132.8 to 620.0 mm2). In conclusion, the results from this study indicate that the presence of a luteal cavity or blood clot has no detrimental effect on pregnancy success after ET in Holstein heifers. Furthermore, no relationship was found between luteinized tissue area at the time of ET and pregnancy rate.

scholarly journals Cleavage Stage versus Blastocyst Stage Embryo Transfer in Oocyte Donation Cycles

Medicina ◽  
2019 ◽  
Vol 55 (6) ◽  
pp. 293 ◽  
Author(s):  
Kontopoulos ◽  
Simopoulou ◽  
Zervomanolakis ◽  
Prokopakis ◽  
Dimitropoulos ◽  
...  
Keyword(s):  
Embryo Transfer ◽  
Oocyte Donation ◽  
Blastocyst Stage ◽  
Pregnancy Rates ◽  
Clinical Pregnancy ◽  
Cleavage Stage ◽  
Sonographic Guidance ◽  
Stage Embryo ◽  
Day 3 Embryo ◽  
Cryopreserved Embryos

Background and Objective: During the last few years, a trend has been noted towards embryos being transferred at the blastocyst stage, which has been associated with improved rates regarding implantation and clinical pregnancy in comparison to cleavage stage embryo transfers. There is a limited number of studies investigating this notion in oocyte donation cycles employing cryopreserved embryos. The aim of this study is to evaluate the implantation potential and clinical pregnancy rates between the day 3 cleavage stage and blastocyst stage embryo transfers in oocyte donation cycles employing vitrified embryos. Methods: This is a retrospective evaluation of oocyte donation frozen–thawed transfers completed in our clinic from January 2017 to December 2017. Intracytoplasmic sperm injection was conducted for all oocytes. Following fertilization, all embryos were cryopreserved either at the cleavage or blastocyst stage. Embryo transfer of two embryos was performed under direct sonographic guidance in all cases. Results: Our results confirmed a 55.6% clinical pregnancy (CP) resulting from day 3 embryo transfers, a 68.8% CP from day 5, and 71.4% CP from day 6. Significantly improved pregnancy rates were related to embryo transfers at the blastocyst stage when compared to cleavage stage transfers (68.9% and 55.6% respectively, p = 0.016). The risk with regards to multiple pregnancies was similar. Conclusion: Our findings indicate that in oocyte donation cycles employing vitrified embryos, embryo transfer at the blastocyst stage is accompanied with a significant improvement in pregnancy rates and merits further investigation.

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