Impact of transabdominal ultrasound guidance on performance and outcome of transcervical uterine embryo transfer

Evidence and consensus on technical aspects of embryo transfer

BACKGROUND

Ultrasound-guided embryo transfer (US-GET) is a widely performed procedure, but standards for the best practice are not available.

OBJECTIVE AND RATIONALE

This document aims to provide an overview of technical aspects of US-GET after considering the published data and including the preparation for the embryo transfer (ET) procedure, the actual procedure, the post-procedure care, associated pathologies, complications and risks, quality assurance and practitioners’ performance.

SEARCH METHODS

A literature search for evidence on key aspects of the ET procedure was carried out from database inception to November 2021. Selected papers (n = 359) relevant to the topic were analysed by the authors. The following key points were considered in the papers: whether ultrasound (US) practice standards were explained, to what extent the ET technique was described and whether complications or incidents and how to prevent such events were reported. In the end, 89 papers could be used to support the recommendations in this document, which focused on transabdominal US-GET.

OUTCOMES

The relevant papers found in the literature search were included in the current document and described according to the topic in three main sections: requirements and preparations prior to ET, the ET procedure, and training and competence for ET. Recommendations are provided on preparations prior to ET, equipment and materials, ET technique, possible risks and complications, training and competence. Specific aspects of the laboratory procedures are covered, in particular the different loading techniques and their potential impact on the final outcomes. Potential future developments and research priorities regarding the ET technique are also outlined.

LIMITATIONS, REASONS FOR CAUTION

Many topics were not covered in the literature review and some recommendations were based on expert opinions and are not necessarily evidence based.

WIDER IMPLICATIONS

ET is the last procedural step in an ART treatment and is a crucial step toward achieving a pregnancy and live birth. The current paper set out to bring together the recent developments considering all aspects of ET, especially emphasizing US quality imaging. There are still many questions needing answers, and these can be subject of future research.

STUDY FUNDING/COMPETING INTEREST(S)

No funding. ADA has received royalties from CRC Press and personal honorarium from Cook, Ferring and Cooper Surgical. The other co-authors have no conflicts of interest to declare that are relevant to the content of this article.

The effect of embryo catheter loading technique on pregnancy rate

Embryo transfer is the most emotional part for patients during in vitro fertilization treatment. Over the last decade, the embryo transfer procedure has undergone numerous changes in the guidelines in order to increase pregnancy rates. One such procedure is the loading of the embryo into the catheter, a thin tube that helps us transfer embryo into the uterine cavity. Very few research studies looked closely at embryo-loading technique per se. Furthermore, different infertility laboratories use various techniques to load embryo. The aim of our study was to compare the two most popular embryo-loading techniques. In 249 women, we transferred embryo aspirated into the catheter with small droplets of air, and in the group of 244 patients, we filled catheter only with fluid. Our main outcome measured was the clinical pregnancy rate. Based on our results, we did not find that embryo-loading technique affected patient's chances of achieving pregnancy.

Correlation of Site of Embryo Transfer with IVF Outcome: Analysis of 743 Cycles from a Single Center

OBJECTIVE

To investigate the influence of site of embryo transfer (ET) on reproductive outcome.

MATERIALS AND METHODS

A retrospective analysis of 743 ultrasound-guided ET in fresh in vitro fertilization (IVF) cycles from a single center over a period of 4 years was conducted. The distance between the fundal endometrial surface and the air bubble was measured, and accordingly, patients were divided into four groups (≤10 mm; >10 and ≤15 mm; >15 and 20 mm; >20 and <25 mm).

SETTING

Tertiary Assisted Reproductive Technology (ART) center.

PATIENTS

All patients enrolled in the IVF program undergoing ET.

INTERVENTIONS

Controlled ovarian hyperstimulation (OS), IVF, and ET.

MAIN OUTCOME MEASURES

Cleavage rate and clinical pregnancy rate.

RESULTS

Clinical pregnancy rate was significantly more in groups 2 and 3 compared to the other groups. Logistic regression analysis showed that one unit increase in embryos transfer will enhance the pregnancy outcome about 3.7 (adjusted odds ratio) times with 95% confidence limits 2.6 to 5.4. Similarly, pregnancy outcome will be 3.1 (95% confidence limits: 1.5-6.4) times higher for distance group >15 and <20 mm compared to less than 10-mm distance group. Ectopic pregnancy rates were similar in all the four groups.

CONCLUSION

The present study demonstrates that site of ET has significant difference on reproductive outcome.

Does the Presence of Blood in the Catheter or the Degree of Difficulty of Embryo Transfer Affect Live Birth?

The technique used for embryo transfer (ET) can affect implantation. Prior research that evaluated the effect of postprocedural blood of the transfer catheter tip have yielded mixed results, and it is unclear whether this is actually a marker of difficulty of the transfer. Our objective was to estimate the effect of blood at the time of ET and the difficulty of ET on live birth rates (LBR). This retrospective cohort study utilized generalized estimating equations (GEEs) with nesting for repeated cycles for all analyses. Univariate modeling was performed and a final multivariate (adjusted) GEE model accounted for all significant confounders. Embryo transfers were subjectively graded (easy, medium, or hard) by a physician at the time of transfer. The presence of blood at ET was associated with more difficult ETs, retained embryos, and presence of mucous in the catheter. In the univariate analysis, ET with blood was not associated with live birth, while the degree of difficulty for ET had a negative impact on LBR. In the final multivariate GEE model, which accounts for repeated cycles from a patient, the only factors associated with an increased LBR were the degree of difficulty of the ET, female age, and blastocyst transfer. After controlling for confounding variables, the presence of blood in the transfer catheter was not associated with the likelihood of pregnancy and thus was not an independent predictor of cycle outcome. This indicates that the difficulty of the transfer itself was a strong negative predictor of pregnancy.

Impact of serum estradiol levels on the implantation rate of cleavage stage cryopreserved-thawed embryos transferred in programmed cycles with exogenous hormonal replacement

PURPOSE

To investigate the impact of late follicular phase serum estradiol (E2) levels on implantation and pregnancy outcomes of cleavage stage cryopreserved/thawed embryos transferred in programmed cycles with exogenous hormonal replacement.

METHODS

Retrospective cohort analysis of IVF patients with transfer of cryopreserved-thawed day-3 embryos in E2 and progesterone (P4) supplemented cycles (n = 208 cycles).

MAIN OUTCOME MEASURES

implantation and pregnancy rates according to late follicular phase serum E2 levels and early secretory phase E2/P4 ratios.

RESULTS

Logistic regression performed for embryo implantation and for pregnancy outcome in relation to E2 (day 15), P4 (day 15 and 16), before (crude analysis) and after adjustment (adjusted analysis) for baseline characteristics (including age, BMI, serum basal cycle day 3 FSH levels, embryo quality, endometrial lining thickness) showed no significant association. Similarly, ROC analysis showed no impact of cycle day 16 E2/P4 ratio.

CONCLUSIONS

Neither late follicular phase serum E2 nor the early E2/P4 ratio were able to predict implantation or pregnancy outcome of day-3 cryopreserved-thawed embryos transferred in artificially programmed cycles.

Embryo catheter loading and embryo culture techniques: results of a worldwide Web-based survey

PURPOSE

To identify trends in embryo catheter loading and embryo culture techniques performed worldwide.

METHODS

A retrospective evaluation using the results of a web-based survey, (IVF Worldwide ( www.IVF-worldwide.com ), was performed.

RESULTS

Responses from 265 centers in 71 countries were obtained. Most centers (97 %) preferred a catheter with its orifice on top, with only 3 % preferring a catheter with the orifice on its side; 41 % preferred a catheter marked for clear ultrasound view. The most commonly-reported methods of embryo loading were medium-air-embryo-air-medium (42 %), medium in catheter with embryo at end (20 %) and medium-air-embryo (15 %). In 68 % of centers the final volume of the catheter was up to 0.3 ml, with only 19 % using 0.3-0.5 ml and 1 % using 0.5-0.7 ml. Using reduced oxygen concentrations for embryo culture was divided between those who used it in combination with the two-gas system (34 %) and those who did not use it at all (39 %); 24 % reported using a three-gas system. Most clinics using reduced oxygen concentrations used it throughout the entire culture period. Half of centers (51 %) reported using reduced oxygen concentrations for the entire IVF population while 6 % reserved it only for blastocyst transfer. The use of sequential media was highly dominant with 40 % reporting its use.

The Impact of the Depth of Embryo Replacement into the Uterine Cavity under Transabdominal Ultrasound Guidance on In Vitro Fertilization and Embryo Transfer Outcome

Aim: The aim of the present study was to determine the importance of the depth of embryo replacement into the uterine cavity (upper or lower half endometrial cavity) on the implantation clinical pregnancy rates.Material and Methods: In this prospective observational were included 160 patients underwent controlled ovarian hyperstimulation followed by IVF/ICSI and embryo transfer. On the day of embryo transfer under direct transabdominal ultrasound guidance, the transfer catheter was advanced to a defined distance from the uterine fundus, up to the point estimated for transfer: 10 ± 2.5 mm (Group A) and 15 ± 2.5 mm (Group B).Results: In total, 160 patients, aged 24-42 years were included in the study. Overall clinical pregnancy rate were 41.2%. Analysis of our results demonstrated that pregnancy rate is significantly influenced by transfer distance from the fundus where the  pregnancy rate decreases from 48.7% in group B to 34.5%  in group A (p<0.05). There was not significantly difference in abortion rate between the two groups.Conclusion: In conclusion, our results suggest that depth of embryo replacement inside the uterine cavity may influence the pregnancy rates and should be considered as an important factor to improve the success of IVF cycles.

In vitro fertilization at a public hospital in Nigeria

OBJECTIVE

To assess the results of an in vitro fertilization program newly established within a conventional infertility program at a university hospital in Nigeria.

METHODS

From June 1, 2007, to June 30, 2011, following unsuccessful conventional treatments, 600 couples were offered in vitro fertilization with (if needed) intracytoplasmic sperm injection in batches of 30 couples. The outcomes measured were duration of ovarian stimulation and rate of ovarian hyperstimulation syndrome; numbers of follicles aspirated, oocytes retrieved, oocytes fertilized, and embryos transferred; and clinical pregnancy rate.

RESULTS

The mean duration of stimulation was 11.8 ± 1.6 days and 1% of the women had severe ovarian hyperstimulation syndrome. The mean number of follicles aspirated was 8 ± 2.8; of oocytes retrieved 6 ± 3.2; and fertilized 3 ± 1.8. The maximum number of embryos transferred per woman was 3. The rates of clinical pregnancy and multiple pregnancy were 30% and 6.0%. The rates of abortion and ectopic pregnancy were 6.6% and 0.6%. The preterm delivery rate was 2.5%.

CONCLUSION

Successfully conducting an assisted reproduction program at a public health facility is feasible in a low-resource country. Treating couples in batches was cost effective, with a low complication rate.

Does storage time influence postthaw survival and pregnancy outcome? An analysis of 11,768 cryopreserved human embryos

OBJECTIVE

To evaluate the impact of cryopreservation storage duration on embryo survival, implantation competence, and pregnancy outcome.

DESIGN

Retrospective study.

SETTING

Academic tertiary-referral infertility center.

PATIENT(S)

In vitro fertilization patients and recipients of oocyte donation cycles who had cryopreserved embryos and underwent at least one thaw cycle from 1986 to 2007.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Postthaw survival proportion and implantation, clinical pregnancy, miscarriage, and live birth rates.

RESULT(S)

Length of storage time did not have a significant effect on postthaw survival for IVF or oocyte donation cycles, or for embryos frozen at the pronuclear or cleavage stages. There was no significant impact of the duration of storage on clinical pregnancy, miscarriage, implantation, or live birth rate, whether from IVF or oocyte donation cycles. Logistic regression analysis demonstrated that the length of storage time or developmental stage at freezing were not predictive of embryo survival or pregnancy outcome. Only oocyte age, survival proportion, and number of transferred embryos were positive predictors of pregnancy outcome.

CONCLUSION(S)

Cryostorage duration did not adversely affect postthaw survival or pregnancy outcome in IVF or oocyte donation patients.

Cumulative exposure to high estradiol levels during the follicular phase of IVF cycles negatively affects implantation

PURPOSE

To investigate the effect of the cumulative exposure to estradiol (E(2)) during the follicular phase on IVF outcome.

METHODS

Patients were stimulated with recombinant FSH after GnRH agonist suppression and had a day 3-embryo transfer. Estrogen exposure was determined as the area under the curve (AUC) for serum E(2) levels measured from the first day of stimulation through the day after hCG administration.

RESULTS

E(2) AUC thresholds for 10th and 90th percentiles were 4704 pg/ml and 16338 pg/ml, respectively. The pregnancy and implantation rates were highest in the 10th-90th percentile group, and were statistically higher in this group than in the >90th percentile group (54.6% vs. 33.3% and 24.8% and 12.9%, respectively, for pregnancy and implantation rates, P < 0.05). Recovered mature oocytes, fertilization, and number and mean score of transferred embryos were similar.

CONCLUSIONS

High cumulative E(2) exposure during the follicular phase of IVF cycles has detrimental effects on implantation.

Is what we clearly see really so obvious? Ultrasonography and transcervical embryo transfer—a review

OBJECTIVE

To critically review the role of ultrasound-guided embryo transfer (ET) and its influence on the outcome of in vitro fertilization (IVF).

DESIGN

Medline review of published manuscripts.

RESULT(S)

Studies evaluating the role of ultrasound-assisted ET have had mixed results, and although meta-analysis of prospective trials suggests an improvement in outcome, limitations in study design may overstate the effect of ultrasonography. Other ET techniques may eliminate the advantages provided by ultrasonography, limiting its benefit to specific clinical scenarios. However, because no trial has demonstrated an adverse effect and because cases that may benefit from its use often cannot be predicted reliably, the routine application of ultrasonography can be justified.

Transabdominal ultrasound–assisted embryo transfer and pregnancy outcome

OBJECTIVE

To assess the clinical value of transabdominal ultrasound (TAS)--assisted embryo transfer on outcomes of in vitro fertilization--embryo transfer (IVF-ET) in comparison to the "clinical touch" method of transcervical embryo transfer by one physician and to determine if transabdominal ultrasound should be applied to all cases of embryo transfer in this practice.

DESIGN

A retrospective comparison study.

SETTING

A university-based IVF practice.

PATIENT(S)

Two hundred forty-nine patients who underwent transcervical transfer of fresh embryos created using autologous oocytes performed by the same physician from July 1, 2003, to June 30, 2004.

INTERVENTION(S)

On selected days, at time of embryo transfer, transabdominal ultrasound was performed to guide catheter placement depth approximately 1 cm from the uterine fundus.

MAIN OUTCOME MEASURE(S)

The presence of at least one gestational sac on ultrasound was compared in the two study groups; additionally, the clinical pregnancy rate (presence of fetal cardiac activity observed on ultrasound), the ectopic pregnancy rate, the biochemical pregnancy rate, and the implantation rate (number of gestational sacs identified on ultrasound per number of embryos transferred) between groups was evaluated. Characteristics of the two cohorts were analyzed to verify similarities between the treatment and control groups, including age of recipient, prior IVF history, day of transfer (day 3 or day 5 after retrieval), difficulty of transfer, the use of a tenaculum, and the quality and number of embryos transferred.

RESULT(S)

No statistical difference was seen in the presence or number of gestational sacs following embryo transfer with or without transabdominal ultrasound guidance.

CONCLUSION(S)

No additional advantage is conferred when using transabdominal ultrasound to perform embryo transfer. In experienced hands, the "clinical touch" method of embryo transfer yields equivalent results to transabdominal ultrasound-guided embryo placement. However, in patients with a prior history of difficult uterine sounding or embryo transfer, transabdominal ultrasound guidance may still play a role.

Effect of coasting on the implantation potential of embryos transferred after cryopreservation and thawing

OBJECTIVE

To examine the effect of withholding gonadotropins on the outcome of embryos after cryopreservation and thawing.

DESIGN

Retrospective clinical evaluation of patients having cryopreserved-thawed ET trials with coasting during the corresponding ovarian stimulation cycle.

SETTING

Academic tertiary clinical care unit.

PATIENT(S)

Patients with cryopreserved embryos having coasting in their fresh IVF cycle and age-matched controls without coasting, both groups receiving the same stimulation protocol (long GnRH agonist plus recombinant FSH).

INTERVENTION(S)

All patients had a cycle in which embryos were transferred fresh and a cycle of thawing of cryopreserved embryos with the aim of transferring in a steroid-supplemented cycle.

MAIN OUTCOME MEASURE(S)

Embryo survival, implantation, and clinical pregnancy rates.

RESULT(S)

Post-thawing embryo survival (66.4% vs. 73%), implantation (12.3% vs. 13.0%), and clinical pregnancy rates (31.5% vs. 38.0%) were similar in study and control groups, respectively. Patients with coasting for > or =3 days had significantly lower post-thawing embryo survival rates compared with patients having shorter duration of coasting (<3 days) and controls. Implantation and pregnancy rates, however, were similar in the three groups.

CONCLUSION(S)

Coasting did not seem to have a detrimental effect on oocyte and embryo quality because the implantation competence of transferred concept after cryopreservation and thawing was similar to that of controls. However, prolonged coasting (> or =3 days) had a subtle negative impact on the post-thaw survival rate.

Controlled ovarian hyperstimulation protocols for in vitro fertilization: two decades of experience after the birth of Elizabeth Carr

OBJECTIVE

To critically discuss the current protocols for the management of controlled ovarian hyperstimulation in assisted reproduction technology.

DESIGN

Review of the literature and presentation of our experience.

MAIN OUTCOME MEASURE(S)

Ovarian response (peak serum estrogen levels, number of oocytes retrieved, quality of oocytes and embryos) and pregnancy outcome (clinical, delivery, and multiple pregnancy rates).

RESULT(S)

Controversies still exist regarding selection of gonadotropin preparation, choice of adjuvant therapy with GnRH analogues, and use of oral contraceptive pills. Patients identified as intermediate responders have an excellent outcome with adjuvant therapy with either a GnRH agonist (long protocol) or a GnRH antagonist, but tailoring of gonadotropin dose must be performed to achieve optimized results. High responders perform favorably with gentler gonadotropin stimulation that minimizes the occurrence of ovarian hyperstimulation syndrome. On the other hand, results in low responders remain suboptimal both in terms of ovarian response and oocyte/embryo quality in spite of a variety of stimulation regimens used.

CONCLUSION(S)

Ovarian stimulation is a critical step in in vitro fertilization therapy. A variety of controlled ovarian hyperstimulation regimens are available and efficacious, but individualization of management is essential and depends on assessment of the ovarian reserve. Identification of the etiologies of poor ovarian response constitutes a formidable challenge facing reproductive endocrinologists.