Performance of different embryo transfer catheters in a human in vitro fertilization program

The use of an embryo transfer simulator to compare transfer techniques and pregnancy outcomes among physicians

Objective

To evaluate the association between embryo transfer techniques and pregnancy outcomes.

Design

This is a prospective observational study with a retrospective cohort.

Setting

University Clinic.

Patients

Patients underwent embryo transfers between 2015 and 2020.

Intervention/Exposure

Fourteen physicians performed 25 mock embryo transfers on the embryo transfer simulator and completed a questionnaire assessing preferred embryo transfer techniques. Quantitative performance metrics on the embryo transfer simulator were measured. Individual physician embryo transfer success rates were retrospectively collected from all fresh and cryopreserved embryo transfers between January 1, 2015, and January 1, 2020. Associations between embryo transfer techniques (preferred technique and simulator performance metrics) and each physician's historical patient pregnancy outcomes were assessed.

Main Outcome Measures

Associations between embryo transfer techniques and live births were assessed.

Results

There were significant differences in embryo transfer techniques between physicians, including touches to the fundus, distance to the fundus, duration of embryo transfer, duration of the complete procedure, time spent navigating the cervical canal, velocity of embryo expulsion, time waited after embryo expulsion, and total score on the embryo transfer simulator. After controlling for confounders and multiple transfers per physician, the duration of embryo transfer was significantly associated with live birth, with longer durations associated with decreased live birth rates. Shorter placement distance to the fundus and higher velocity of embryo expulsion were both significantly associated with higher rates of ectopic pregnancy.

Conclusions

This study revealed significant differences in transfer techniques among physicians. The use of the embryo transfer simulator for physicians in practice can elucidate differences and create opportunities for data-driven improvement in embryo transfer success rates.

Interventions to optimize embryo transfer in women undergoing assisted conception: a comprehensive systematic review and meta-analyses

BACKGROUND

Several interventions and techniques are suggested to improve the outcome of embryo transfer (ET) in assisted conception. However, there remains no consensus on the optimal practice, with high variations among fertility specialists.

OBJECTIVE AND RATIONALE

We conducted a comprehensive systematic review and meta-analyses of randomized controlled trials (RCTs) aiming to identify effective interventions that could be introduced around the time of ET to improve reproductive outcomes.

SEARCH METHODS

We searched the electronic databases (MEDLINE, EMBASE and Cochrane CENTRAL) from inception until March 2021 using a multi-stage search strategy of MeSH terms and keywords, and included all RCTs that evaluated an intervention in the 24-h period before/after ET in women undergoing IVF/ICSI. Our primary outcome was clinical pregnancy rate post-ET confirmed as viable pregnancy on ultrasound scan. We assessed the risk of bias in included trials and extracted data in duplicate. We pooled data using a random-effect meta-analysis and reported using risk ratio (RR) with 95% CI. We explored publication bias and effect modifiers using subgroup analyses.

OUTCOMES

Our search yielded 3685 citations of which we included 188 RCTs (38 interventions, 59 530 participants) with a median sample size of 200 (range 26-1761). The quality of included RCTs was moderate with most showing a low risk of bias for randomization (118/188, 62.8%) and attrition (105/188, 55.8%) but there was a significant risk of publication bias (Egger's test P = 0.001). Performing ET with ultrasound guidance versus clinical touch (n = 24, RR 1.265, 95% CI 1.151-1.391, I2 = 38.53%), hyaluronic acid versus routine care (n = 9, RR 1.457, 95% CI 1.197-1.261, I2 = 46.48%) and the use of a soft versus hard catheter (n = 27, RR 1.122, 95% CI 1.028-1.224, I2 = 57.66%) led to higher clinical pregnancy rates. Other pharmacological add-ons also showed a beneficial effect including granulocyte colony-stimulating factor (G-CSF: n = 4, RR 1.774, 95% CI 1.252-2.512, I2 = 0), Atosiban (n = 7, RR 1.493, 95% CI 1.184-1.882, I2 = 68.27%) and hCG (n = 17, RR 1.232, 95% CI 1.099-1.382, I2 = 57.76%). Bed rest following ET was associated with a reduction in clinical pregnancy (n = 6, RR 0.857, 95% CI 0.741-0.991, I2 = 0.01%). Other commonly used interventions, such as non-steroidal anti-inflammatory drugs, prophylactic antibiotics, acupuncture and cervical mucus removal, did not show a significant benefit on reproductive outcomes. Our effect estimates for other important outcomes, including miscarriage and live birth, were limited by the varied reporting across included RCTs.

WIDER IMPLICATIONS

Using ultrasound guidance, soft catheters and hyaluronic acid at the time of ET appears to increase clinical pregnancy rates. The use of Atosiban, G-CSF and hCG showed a trend towards increased clinical pregnancy rate, but larger trials are required before adopting these interventions in clinical practice. Bed rest post-ET was associated with a reduction in clinical pregnancy and should not be recommended.

Is There Any Effect of the Physician Performing Embryo Transfer in IVF-ICSI Treatment: A Prospective Cohort Study

OBJECTIVE

 To evaluate whether there is an effect of the physician who transfers the embryos on pregnancy rates in in vitro fertilization-intracytoplasmic sperm injection (IVF-ICSI) treatment.

METHODS

 A total of 757 participants were analyzed between 2012 and 2017. Participants were classified according to 3 physicians who transferred the embryos: ([group 1 = 164 patients]; [group 2 = 233 patients]; [group 3 = 360 patients]). Baseline parameters and IVF-ICSI outcomes were compared between the groups.

RESULTS

 No differences were determined between the groups regarding the baseline parameters (age, age subgroups [20-29, 30-39, and ≥ 40 years old)], body mass index (BMI), smoking status, infertility period, cause of infertility, baseline follicle stimulating hormone, luteinizing hormone, estradiol (E₂), thyroid stimulating hormone, prolactin levels, antral follicle count, duration of stimulation, stimulation protocol, gonadotropin dose required, maximum E₂ levels, progesterone levels, endometrial thickness on human chorionic gonadotropin (hCG) administration and transfer days (p > 0.05). The numbers of oocytes retrieved, metaphase II (MII), 2 pronucleus (2PN), , transferred embryo, fertilization rate, day of embryo transfer, the catheter effect and embryo transfer technique, and clinical pregnancy rates (CPRs) were also comparable between the groups (p > 0.05).

CONCLUSION

 Our data suggests that the physician who transfers the embryos has no impact on CPRs in patients who have undergone IVF-ICSI, but further studies with more participants are required to elucidate this situation.

Ultrasound versus 'clinical touch' for catheter guidance during embryo transfer in women

BACKGROUND

Many women undergoing an assisted reproductive technology (ART) cycle will not achieve a live birth. Failure at the embryo transfer stage may be due to lack of good-quality embryo/s, lack of uterine receptivity, or the transfer technique itself. Numerous methods, including the use of ultrasound guidance for proper catheter placement in the endometrial cavity, have been suggested as more effective techniques of embryo transfer. This review evaluates the efficacy of ultrasound-guided embryo transfer (UGET) compared with 'clinical touch' (CTET), which is the traditional method of embryo transfer and relies on the clinician's tactile senses to judge when the transfer catheter is in the correct position.

OBJECTIVES

To determine whether ultrasound guidance compared with clinical touch improves pregnancy outcomes in women undergoing embryo transfer during ART cycles.

SEARCH METHODS

For the 2016 update of this review, we ran updated searches in the Cochrane Gynaecology and Fertility Group trials register (May 2015), the Cochrane Central Register of Controlled Trials (the Cochrane Library, May 2015), MEDLINE (2009 to May 2015), and EMBASE (2009 to May 2015). We also handsearched relevant conference proceedings: American Society for Reproductive Medicine (ASRM), European Society for Human Reproduction and Embryology (ESHRE), and International Federation of Gynecology and Obstetrics (FIGO). There were no language restrictions.

SELECTION CRITERIA

We included only randomised controlled trials.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed eligibility and quality of trials and extracted data from those selected. We calculated odds ratio (OR) and 95% confidence interval (CI) for dichotomous outcomes. No outcomes were reported using continuous data. We assessed the overall quality of the evidence for the main findings using the GRADE working group methods.

MAIN RESULTS

This systematic review now has 21 included studies (four of which we added in the 2016 update), two studies awaiting assessment, and 47 excluded studies. In total, data for meta-analyses were available in 21 trials (n = 6218 women), of which only four reported live births.UGET was associated with an increased chance of a live birth/ongoing pregnancy compared with CTET (OR 1.47, 95% CI 1.30 to 1.65; 13 trials; n = 5859 women; I(2) = 74%; low-quality evidence). Sensitivity analysis by including only trials with low risk of selection bias or by using a random-effects model did not alter the effect. We estimate that for women with a chance of a live birth/ongoing pregnancy of 23% using CTET, this would increase to between 28% and 33% using UGET. We considered the quality of the evidence using GRADE methodology to be low.UGET was associated with an increase in the chance of a clinical pregnancy (OR 1.31, 95% CI 1.17 to 1.45; 20 trials; n = 6711 women; I(2) = 42%; moderate-quality evidence). We identified no differences between groups for the incidence of adverse events including multiple pregnancy, ectopic pregnancy, or miscarriage. These events were relatively rare, and sample sizes limited the ability to detect such differences.

AUTHORS' CONCLUSIONS

The evidence suggests ultrasound guidance improves the chance of live birth/ongoing and clinical pregnancies compared with clinical touch, without increasing the chance of multiple pregnancy, ectopic pregnancy, or miscarriage. Methodological limitations included: only four studies reporting details of both computerised randomisation techniques and adequate allocation concealment, only four studies reported on the outcome of live birth, and none of the nine studies that reported on ongoing pregnancy reported on live birth, suggesting possible reporting bias. Adequate reporting of randomisation and allocation concealment will improve the quality of future studies. The primary outcome measure of future studies should be the reporting of live births per woman randomised.

Ultrasound guidance during embryo transfer: a systematic review and meta-analysis of randomized controlled trials

OBJECTIVES

To summarize the current evidence on the effect of using ultrasound (US) guidance during embryo transfer (ET).

METHODS

In this systematic review, we included randomized controlled trials examining the effect of the use of US guidance during ET; data from studies using the same catheter type in study arms were not pooled with the results from studies that used different catheter types.

RESULTS

Twenty-one studies were included in the quantitative analysis: 18 compared 'US guidance' with 'clinical touch', of which one was subsequently excluded from the quantitative meta-analysis owing to a lack of available data, three studies compared transvaginal US guidance with transabdominal US guidance, and one study compared 'hysterosonometry before ET' with US guidance. Comparison of the use of US guidance with clinical touch, in studies that used the same catheter type in the study arms, indicated a benefit of using US guidance during ET on the rates of live birth (relative risk (RR), 1.48 (95% CI, 1.16-1.87)), based on two studies involving 888 women with moderate-quality evidence, and on the rates of clinical pregnancy (RR, 1.32 (95% CI, 1.18-1.46)), based on 13 studies involving 3641 women with high-quality evidence. However, when comparing the use of US guidance with clinical touch in studies that used different catheter types, the results suggest that using US guidance during ET has no effect on the rates of reproductive outcome: live birth (RR, 0.99 (95% CI, 0.83-1.19)), based on one study involving 1649 women with moderate-quality evidence; clinical pregnancy (RR, 1.04 (95% CI, 0.89-1.21)), based on five studies involving 2949 women with moderate-quality evidence. The estimates for the rate of miscarriage and for the other identified comparisons were imprecise.

CONCLUSIONS

The available evidence suggests that there is a benefit of using US guidance during ET. However, both US-guided transfer and clinical touch should be considered acceptable, as the benefit of US is not large and should be balanced against the increased cost and need to change the catheter type. More studies are required before conclusions can be drawn regarding the effect of other techniques on reproductive outcome.

Embryo transfer by reproductive endocrinology fellows vs attending physicians: are live birth rates comparable?

OBJECTIVE

To compare live birth rates following ultrasound-guided embryo transfer (ET) by reproductive endocrinology and infertility fellows versus attending physicians.

STUDY DESIGN

Women who underwent their first day-3, fresh, nondonor ET between Oct. 1, 2005, and April 1, 2011, at our academic center were included in this retrospective cohort study. Embryos were designated high quality if they had 8 cells, less than 10% fragmentation, and no asymmetry. ET was performed with the afterload technique under ultrasound guidance. Categorical variables were evaluated with the χ(2) test and continuous variables with the Student t test. Logistic regression was performed to assess the relationship between ET physician and live birth rate while adjusting for potential confounders.

RESULTS

Seven hundred sixty women underwent ET by an attending physician, and 104 by a fellow. Baseline characteristics were similar between the groups. The live birth rate was 31% following ET by an attending physician, compared with 34% following ET by a fellow (P = .65). Logistic regression adjusting for potential confounders demonstrated no significant association between ET physician and live birth rate.

CONCLUSION

This retrospective study demonstrated no significant difference in live birth rates following ultrasound-guided ET by fellows vs attending physicians at our institution. These data suggest that academic practices using the afterload method and ultrasound guidance can train fellows to perform ET without compromising success rates.

Individualized embryo transfer training: timing and performance

STUDY QUESTION

How long is the individualized training and the stability of competence for the embryo transfer (ET) technique?

SUMMARY ANSWER

The embryo transfer technique is easy-to-learn, hardly unlearned, and training should be individualized by monitoring with learning curve-cumulative summation (LC-CUSUM) curves.

WHAT IS KNOWN ALREADY

Like many medical procedures, embryo transfer is an operator-dependent technique. Individualized or standardized training of these medical procedures should be monitored to determine when competence is acquired.

STUDY DESIGN, SIZE, DURATION

This prospective, monocentric study involving five embryo transfer trainees was carried out between August 2011 and November 2012.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The study was carried out in a large private clinic. Five gynaecologist trainees during their first year of assisted reproduction subspecialty performed embryo transfer for patients undergoing either fresh IVF, oocyte donor IVF, or frozen embryo transfer. There were 586 embryo transfers performed in 96 sessions of 3-10 embryo transfers each. An embryo transfer was considered successful if it gave rise to a positive pregnancy test 14 days later. LC-CUSUM and cumulative summation (CUSUM) curves were used to determine when competence was acquired and whether it was maintained over time, respectively. The length of time between two consecutive sessions was assessed for an effect on consolidation of the acquired competence.

MAIN RESULTS AND THE ROLE OF CHANCE

We observed that all five trainees became proficient in embryo transfer by procedure 15 (after procedure 15, 9, 7, 13 and 9, respectively). Once competence was achieved, one of the five trainees showed a loss of proficiency. After having acquired competence, the median pregnancy rate per embryo transfer session was significantly lower when the interval between consecutive embryo transfer sessions was ≥10 days compared with <10 days (20.0 versus 46.7%; P = 0.006).

LIMITATIONS, REASONS FOR CAUTION

The patient groups included in the study were heterogeneous (IVF, oocyte donor IVF and frozen embryo transfer) and their outcomes are very variable; thus the distribution and proportion of these groups can determine the timing of competence acquisition. Our data show that low numbers of embryo transfer are needed to acquire competence, but since a relative high percentage of embryo transfers in our practice are from oocyte donor IVF, extrapolation of the findings to other clinical context should be done with caution.

WIDER IMPLICATIONS OF THE FINDINGS

Personalized embryo transfer training is feasible and useful, allowing clinics, on one hand, to offer a maximum chances of pregnancy with fully trained personnel, and the other hand, to avoid the superfluous and costly overtraining of already proficient trainees. Furthermore, it is advisable to maintain a short interval of time between consecutive embryo transfer sessions after a trainee has acquired competence, to avoid a significant drop in the resulting pregnancy rate.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported in part by funding from Fundació Privada EUGIN. There are no conflicts of interest to declare.

[Professional Practice Evaluation: How to improve quality management in procreation centers?]

OBJECTIVES

The Professional Practice Evaluation (PPE) is at the heart of quality management in procreation centers. Hereby, we report 3 years of EPP in Cytogenetics and Reproduction laboratory in Amiens University Hospital.

PATIENTS AND METHODS

This PPE is based upon prospective analysis of in vitro fertilization techniques regarding two major parameters: clinically in improving embryo transfer and biologically by determining fecundation levels. Clinical pregnancies in "Top Quality" trial is chosen as a major indicator of our results.

RESULTS

Per transfer, there is an increase of 8% for clinical pregnancies and 31% in "Top quality" trials.

DISCUSSION AND CONCLUSION

The improvement in our results allowed us to propose, in favourable conditions, single embryo transfer.

Quality Management Issues in the Assisted Reproduction Laboratory

In the United States, the Clinical Laboratory Improvement Act (CLIA) of 1988 describes requirements and guidelines for implementing a quality control/quality assurance (QC/QA) program for moderate and high complexity laboratories. These requirements and guidelines apply to Assisted Reproductive Technology (ART) laboratories as well. The general topic of QC and QA as it pertains to in vitro fertilization (IVF) and embryo transfer (ET) is extensively reviewed. This review summarizes many of the QC and QA events that contribute to the advancement of knowledge in this biotechnological field. These events include control of the culture environment inside and outside of the incubator, as well as factors that affect culture media. This review also discusses, in considerable detail, the QC and the QA that pertain to equipment used within the laboratory and how to control for potential contaminants, which reside within the laboratory. This review provides evidence to indicate the need for laboratory personnel to monitor quality improvement issues on a continuous basis. Personnel must be willing to change as improvements in technology occur in order to meet the ever-evolving demands of a more difficult patient population. Suggestions for meeting these demands are offered.

Ultrasound versus 'clinical touch' for catheter guidance during embryo transfer in women

BACKGROUND

Many women undergoing an Assisted Reproductive Technology (ART) cycle will not achieve a live birth. Failure at the embryo transfer stage may be due to lack of good quality embryo/s, lack of uterine receptivity, or the transfer technique itself. Numerous methods, including the use of ultrasound guidance for proper catheter placement in the endometrial cavity, have been suggested as a more effective technique of embryo transfer. This review evaluates the effectiveness of ultrasound guided embryo transfer (UGET) compared with 'clinical touch' (CTET) the traditional method of embryo transfer.

OBJECTIVES

To determine whether ultrasound guidance influences treatment outcomes in women undergoing embryo transfer (ET) during assisted reproductive technology (ART) cycles.

SEARCH STRATEGY

Electronic databases were searched in November 2009. We searched the Cochrane Menstrual Disorders and Subfertility Group trials register (searched November 2009), the Cochrane Central Register of Controlled Trials (The Cochrane Library, Issue 3, 2009), MEDLINE (1970-2009), EMBASE (1985-2009), BIO Extracts (1980-2009). Relevant conference proceedings were also hand searched (ASRM, ESHRE and FIGO).

SELECTION CRITERIA

Only randomised controlled trials were included.

DATA COLLECTION AND ANALYSIS

Two reviewers independently assessed eligibility and quality of trials and extracted data from those selected.

MAIN RESULTS

This update identified 59 potential trials of which 42 were excluded. Data for analysis was available in seventeen studies. One study reported live births and personal communication resulted in data relating to this outcome being obtained in two additional studies. There is no evidence of a significant difference in the outcome of live birth (OR 1.14 (95%CI0.93 to 1.39; P=0.02) although heterogeneity was high (64%) and the results should be interpreted with caution. Seven studies reported on ongoing pregnancies. The ongoing pregnancies per woman randomised associated with UGET (441/1254) was significantly higher than for clinical touch (350/1218) OR 1.38, 95%CI 1.16 to 1.64, P<0.0003). No statistically significant differences in the incidence of adverse events were identified between the comparison groups. These events are relatively rare and sample sizes limit the ability to detect such differences.

AUTHORS' CONCLUSIONS

The studies are limited by their quality with only two studies reporting details of both computerised randomisation techniques and adequate allocation concealment. Ultrasound guidance does appear to improve the chances of live/ongoing and clinical pregnancies compared with clinical touch methods. The quality of future studies should be improved with adequate reporting of randomisation, allocation concealment, and power calculations. The primary outcome measure of future studies should be the reporting of live births per woman randomised.

Hysteroscopic evaluation of endocervical and endometrial lesions observed after different procedures of embryo transfer: a prospective comparative study

OBJECTIVE

Endocervical and endometrial damage observed after different procedures of embryo transfer (ET) were investigated using diagnostic hysteroscopy.

STUDY DESIGN

Prospective, descriptive and comparative study, in an Infertility centre, University Hospital. Hundred consecutive infertile patients with a normal uterine cavity, included in an IVF program, were enrolled between May 1st, 2006 and April 30th, 2007. All the patients had a diagnostic hysteroscopy immediately after trial ET using soft ET catheters: (i) IVF Sydney Set (Cook, Limerick, Ireland) (n=27), (ii) Elliocath (Ellios, Paris, France) (n=34), (iii) Frydman classic 4.5 (CCD, Paris, France) (n=19), and rigid ET catheters: Memory Frydman 4.5 (CCD, Paris, France) (n=20). All the procedures were recorded and blindly reviewed. Data were analyzed using a Kruskal-Wallis test for age and severity of endometrial lesions, or Fisher's exact test for binary criteria.

RESULTS

Endocervical lesions were more frequently encountered in the soft (63%) and rigid (85%) Frydman's catheter groups compared to other groups (Elliocath: 29%, IVF Sydney Set: 26%; p<0.0001). Presence of blood on the catheter, and endometrial lesions were significantly less frequent in soft catheter groups compared to the rigid catheter group (p<0.0001). Severe endometrial lesions were less frequently observed when soft catheters were used (85%, 53%, 32%, 11% for Memory Frydman, Frydman classic, Elliocath and IVF Sydney Set, respectively; p<0.0001). The presence of blood on the catheter signed severe endometrial lesions.

CONCLUSION

All ET catheters can lead to endocervical and endometrial damage. Severe endometrial lesions were less frequent when soft catheters were used.

The effect of retained embryos on pregnancy outcome in an in vitro fertilization and embryo transfer program

OBJECTIVE

The purpose of this study was to determine the incidence of retained embryos and its impact on pregnancy outcome in the absence of known risk factors like blood and mucus in the transfer catheter. The factors that could be associated with embryo retention were also investigated.

STUDY DESIGN

The results of all embryo transfer procedures performed at Ankara IVF Center between January 2003 and December 2005 were analyzed retrospectively. Three hundred and five embryo transfers, in which the transfer catheter was contaminated with blood or mucus, were excluded and the remaining 1,454 embryo transfers, with clean catheter, were enrolled into the study. Both fresh (n=1,422) and frozen (n=32) embryo transfers were included.

RESULTS

The overall incidence of retained embryos during study period was 2.8% (41/1,454) following a clean initial embryo transfer. The mean age of the female partner, mean number of retrieved oocytes, MII oocytes, fertilized oocytes and the embryos transferred were similar in patients with and without retained embryos. The 1,454 embryo transfers performed during the study period resulted in 712 pregnancies (49%), of which 639 proved to be clinical pregnancies with a rate of 44%. The implantation rate was 22.8%. Pregnancy outcomes including positive beta-hCG (58.5% versus 48.7%), biochemical (4.7% versus 5.1%) and clinical pregnancy rates (53.6% versus 43.6%), implantation rate (24% versus 22.7%) and multiple pregnancy rate (36.3% versus 44.7%) were not significantly different between patients with and without retained embryos. An influence of individual physicians and embryologists on the frequency of retained embryos was not detected. The type of embryo transfer catheter used did not show any difference in terms of embryo retention. The cleavage stages of embryos were not different between groups. Although it was not statistically significant, the number of embryos transferred appeared to be a potentially confounding factor for retained embryos (p=0.053) and it might be significant in a slightly larger sample. When transfer of one or two embryos was compared to three or more embryos, the likelihood of retained embryos increased from 1.2% (4/321) to 3.2% (37/1,133).

CONCLUSION

Retained embryos in the transfer catheter and immediate retransfer of them have no adverse impact on clinical pregnancy and implantation rates unless other previously reported signs of difficult transfer are also observed.

Prospective randomized comparison of Wallace and Labotect embryo transfer catheters

The aim of this study was to compare the clinical performance of Wallace and Labotect embryo transfer catheters in a single assisted reproduction centre. A total of 260 women undergoing embryo transfer were randomized between Wallace and Labotect catheters. When both catheters failed to negotiate the cervical canal, the transfer was accomplished with a stiff catheter. Intention to treat analysis revealed that Wallace and Labotect embryo transfer catheters yielded statistically similar clinical pregnancy (44.6 versus 34.6%), implantation (23.2 versus 18.9%) and ongoing pregnancy (38.5 versus 27.7%) rates. As treated analysis revealed clinical pregnancy rates of 42.5 versus 35.4%, implantation rates of 22.3 versus 20.6% and ongoing pregnancy rates of 36.8 versus 28.3% with Wallace and Labotect catheters respectively. Catheter change due to unsuccessful negotiation of the internal cervical os was significantly more frequently necessary when embryo transfer was first intended with the Wallace than the Labotect catheter (P < 0.001; 33 and 2% respectively). Although not being statistically significant, the observed differences may be regarded as clinically important and may reach statistical significance in larger trials. More trials are necessary before reaching a definitive conclusion regarding the performance of the Labotect embryo transfer catheter.

Comparison of pregnancy rates for two embryo-transfer catheters

OBJECTIVE

To compare two flexible catheters and determine whether pregnancy rates (PRs) differed.

DESIGN

Prospective, randomized pilot study.

SETTING

Tertiary-care infertility practice.

PATIENT(S)

The subjects for this study were 100 women undergoing assisted reproductive technology (ART) cycles between September 2003 and October 2005.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE

Clinical PR for Edwards-Wallace (Cooper Surgical, Shelton, CT) and Cook World (Cook Urological, Spencer, IN) embryo-transfer (ET) catheters.

RESULT(S)

The outcomes of pregnancy between the Edwards-Wallace and Cook World ET catheters were not significantly different. Use of the flare stimulation protocol resulted in a significantly lower PR compared to long luteal and antagonist protocols. No other variable affected PR.

CONCLUSION(S)

A 5% difference in PR was demonstrated between ET catheters; however, this study does not have the power to detect a significant difference in clinical PR between the two catheter groups. The pilot study demonstrates good design due to the lack of significant differences between the variables when stratifed by cather as well as pregnancy status. In a larger study, the flare protocol should be excluded.

Ultrasound versus 'clinical touch' for catheter guidance during embryo transfer in women

BACKGROUND

Many women undergoing an Assisted Reproductive Technology (ART) cycle will not achieve a live birth. Failure at the embryo transfer stage may be due to poor embryo quality, lack of uterine receptivity, or the transfer technique itself. Numerous methods, including the use of ultrasound guidance for proper catheter placement in the endometrial cavity, have been suggested as a means of improving the technique of embryo transfer. This review evaluates the effectiveness of ultrasound (UGET) in comparison with 'clinical touch' embryo transfer (CTET) the traditional method of embryo transfer.

OBJECTIVES

:To determine whether ultrasound guidance influences treatment outcomes in women undergoing embryo transfer (ET) during assisted reproductive technology (ART) cycles.

SEARCH STRATEGY

All electronic databases were searched on 20 th August 2006. We searched the Cochrane Menstrual Disorders and Subfertility Group trials register (searched August 2006), the Cochrane Central Register of Controlled Trials (The Cochrane Library, Issue 1, 2006), MEDLINE (1970-2006), EMBASE (1985-2006), BIO Extracts (1980-2006). Relevant conference proceedings were also hand searched (ASRM, ESHRE and FIGO).

SELECTION CRITERIA

Only randomised controlled trials were included.

DATA COLLECTION AND ANALYSIS

Two reviewers independently assessed eligibility and quality of trials and extracted data from those selected.

MAIN RESULTS

Thirteen out of fifteen identified studies were eligible for analysis. No study reported live births, however, personal communication resulted in data relating to this outcome being obtained in two of the studies. Six studies reported on ongoing pregnancies. The live birth/ ongoing pregnancies per woman randomised associated with UGET (452/1376) was significantly higher than for clinical touch (353/1338) OR 1.40, 95%CI 1.18 to 1.66, P<0.0001). This means, for example, that for a population of women with a 25% chance of pregnancy using clinical touch this would be increased to 32% (28% to 46%) by using UGET. There were no statistically significant differences in the incidence of adverse events between the two comparison groups with the exception of blood on the catheter.

AUTHORS' CONCLUSIONS

The studies are limited by their quality with only one of the thirteen studies reporting details of both computerised randomisation techniques and adequate allocation concealment. Ultrasound guidance does appear to improve the chances of live/ongoing and clinical pregnancies compared with clinical touch methods. The quality of future studies should be improved with adequate reporting of randomisation, allocation concealment, and power calculations. The primary outcome measure of future studies should be the reporting of live births per woman randomised.

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.

Firm embryo transfer catheters for assisted reproduction: a systematic review and meta-analysis using direct and adjusted indirect comparisons

A systematic review of published evidence on firm embryo transfer catheters is presented. Extensive searches were conducted for full-text manuscripts, abstracts, ongoing and unpublished trials. Direct and adjusted indirect comparisons were undertaken, where appropriate. Twenty-six randomized controlled trials comparing embryo transfer catheters were identified. Only two trials (314 transfers) compared different firm embryo catheters. Using direct comparison, both the Tom Cat and Tefcat catheters demonstrated statistically significant increased chances of clinical pregnancy compared with the Tight Difficult Transfer (TDT) catheter (P=0.007; OR=3.67, 95% CI=1.48-9.10 and P<0.0001; OR=4.71, 95% CI=2.34-9.48 respectively). The implantation rates were also higher with the Tom Cat and Tefcat catheters than the TDT catheter (P=0.005; OR=3.67, 95% CI=1.48-9.10 and P<0.00001; OR=4.29, 95% CI=2.45-7.50 respectively). Using adjusted indirect comparison, Tom Cat and Tefcat catheters were compared, and shown to have similar pregnancy and implantation rates (OR=0.99; 95% CI=-0.87-1.79 and OR=0.86; 95% CI=-0.77-1.35). In conclusion, both Tom Cat and Tefcat catheters give better outcomes than the TDT catheter, but are similar to each other.

Impact of hypnosis during embryo transfer on the outcome of in vitro fertilization-embryo transfer: a case-control study

OBJECTIVE

To investigate whether hypnosis during ET contributes to successful IVF/ET outcome.

DESIGN

Case-control clinical study.

SETTING

Academic Fertility and IVF Unit, Soroka Medical Center, Beer-Sheva, Israel.

PATIENT(S)

Infertile couples undergoing IVF.

INTERVENTION(S)

Ninety-eight IVF/ET cycles with hypnosis during the ET procedure were matched with 96 regular IVF/ET cycles.

MAIN OUTCOME MEASURES

Comparison of clinical pregnancy and implantation rates between the two groups.

RESULT(S)

We obtained 52 clinical pregnancies out of 98 cycles (53.1%) with an implantation rate of 28% among hypnosis IVF/ET cycles, and 29 out of 96 (30.2%) clinical pregnancies and an implantation rate of 14.4% in the control cycles. Our overall IVF program pregnancy rate for the same period was 32.1%. Logistic regression analysis was performed emphasizing the positive contribution of hypnosis to the IVF/ET conception rates.

CONCLUSION(S)

This study suggests that the use of hypnosis during ET may significantly improve the IVF/ET cycle outcome in terms of increased implantation and clinical pregnancy rates. Furthermore, it seems that the patients' attitude to the treatment was more favorable.

A review and meta-analysis of prospective trials comparing different catheters used for embryo transfer

OBJECTIVE

To determine the relative efficacy of different types of embryo transfer (ET) catheters.

DESIGN

Systematic review and meta-analysis of prospective randomized, controlled trials comparing at least two different ET catheters.

SETTING

Infertility centers providing treatment with in vitro fertilization/embryo transfer (IVF-ET).

PATIENT(S)

Women undergoing ET.

INTERVENTION(S)

Embryo transfer with soft or hard catheters.

MAIN OUTCOME MEASURE(S)

Clinical pregnancy rate.

RESULT(S)

A total of seven prospective trials were identified that compared soft (Cook or Wallace) catheters with hard (TDT, Frydman, Tomcat, Rocket) catheters. The meta-analysis demonstrated an increased chance of clinical pregnancy when soft ET catheters were used. The TDT catheter was compared against both soft catheters and other hard catheters, showing decreased chance of clinical pregnancy when the TDT catheter was used. Six more prospective trials were identified comparing the Cook and Wallace soft catheters, and the meta-analysis of these data showed no demonstrable difference in clinical pregnancy rates.

CONCLUSION(S)

An increased chance of clinical pregnancy is achieved when soft ET catheters are used. There appears to be little difference between the Cook and Wallace soft catheters.

Embryo transfer: factors involved in optimizing the success

PURPOSE OF REVIEW

Embryo transfer is arguably the most critical step in assisted reproduction. The purpose of this article is to review the different aspects of the procedure in the light of recent evidence.

RECENT FINDINGS

Randomized trials have shown that significantly higher pregnancy rates are obtained when embryo transfer is performed under ultrasound guidance, the embryos are deposited in the middle part of the uterine cavity, an atraumatic technique is used and when low-dose aspirin is routinely administered following the procedure. Blood in the catheter and leaving the embryos inside it for more than 120 s diminish the pregnancy rate significantly. Air in the catheter, immediate removal of the catheter, performing two transfers in the same cycle, prolonged bed rest, sexual intercourse after embryo transfer or the use of sildenafil do not affect the results. Based on currently available evidence, Cochrane reviews have concluded that the live birth rate is not increased by delaying embryo transfer from day two to three or to the blastocyst stage, and that single embryo transfer leads to lower live birth rates than the transfer of two embryos. The value of a mock transfer a few days before the actual procedure has been challenged as the position of the uterus may change. The effect of holding the cervix with a volsellum, routinely administering antibiotics and the superiority of one catheter over the others is still to be determined.

SUMMARY

Recent studies confirm the importance of the various aspects of embryo transfer. More randomized studies are needed to further evaluate them.

Factors affecting assisted reproductive technology (ART) pregnancy rates: a multivariate analysis

PURPOSE

To determine factors instrumental in achieving a clinical pregnancy in assisted reproductive technology (ART) patients.

METHODS

This study included 205 women undergoing their first ART cycle. Univariate and multivariate analyses were performed for patient demographics, in vitro production data, and factors associated with embryo transfer. Odds ratios (OR) were performed where appropriate.

RESULTS

Our analyses indicated that age (OR: 0.879), specific year in which the cycle was performed (OR: 2.959), and use of intracytoplasmic sperm injection (OR: 2.867) altered potential pregnancy rate. In addition, percent fertilization (OR: 1.028), number of embryos transferred (OR: 1.842), type of catheter used to transfer the embryos (OR: 0.377), presence of blood on the catheter (OR .414), and embryologist (OR: 2.338) also altered pregnancy rate.

CONCLUSIONS

Our data indicate patients' age, use of the Cook catheter, and presence of blood on the catheter reduce pregnancy rates. Performing ART in 1999, using ICSI, increasing fertilization rate, increasing number of embryos transferred (albeit less desirable when the chance of multiple gestation may occur), and transferring embryos via a particular embryologist, improve pregnancy rates.

Predictive factors for embryo implantation potential

In spite of recent improvements in IVF, pregnancy rates have not increased significantly and one of the major problems remains the high multiple pregnancy rate. Better criteria are therefore necessary to establish the viability of a transferable embryo. Early prognosis of the developmental fate of the oocyte would help in selecting the best embryos to transfer, but non-invasive selection at the oocyte stage (extracytoplasmic and intracytoplasmic morphology) has proved to be of little prognostic value. Recently, it has been shown that follicular vascularization appears to be predictive of oocyte developmental fate, making it a good first-step approach for selection. Observation of pronuclei patterns at the zygote stage appears to offer an additional prognostic tool, correlating well with IVF outcome. Morphological evaluation of the embryo at days 2-3 remains the most used and valid method of selection, even though it is not sufficient to select embryos with the higher implantation potential. Blastocyst culture is another possible strategy for selecting the best embryos with reduced risk of aneuploidies, though not all major chromosomal aberrations are excluded by prolonged in-vitro culture. In summary, selecting the best embryo for transfer is a decision that should be based on choices made during the different stages of assisted reproductive technologies.

Soft versus firm embryo transfer catheters for assisted reproduction: a systematic review and meta-analysis*

BACKGROUND

The true impact of the embryo transfer catheter choice on an IVF programme has not been fully examined. We therefore decided to systematically review the evidence provided in the literature so that we may evaluate a single variable in relation to a successful transfer, the firmness of the embryo transfer catheter.

METHODS

An extensive computerized search was conducted for all relevant articles published as full text, or abstracts, and critically appraised. In addition, a hand search was undertaken to locate any further trials.

RESULTS

A total of 23 randomized controlled trials (RCT) evaluating the types of embryo transfer catheters were identified. Only ten of these trials, including 4141 embryo transfers, compared soft versus firm embryo catheters. Pooling of the results demonstrated a statistically significantly increased chance of clinical pregnancy following embryo transfer using the soft (643/2109) versus firm (488/2032) catheters [P = 0.01; odds ratio (OR) = 1.39, 95% confidence interval (CI) = 1.08-1.79]. When only the truly RCT were analysed, the results were again still in favour of using the soft embryo transfer catheters [soft (432/1403) versus firm (330/1402)], but with a greater significance (P < 0.00001; OR = 1.49, 95% CI = 1.26-1.77).

CONCLUSION

Using soft embryo transfer catheters for embryo transfer results in a significantly higher pregnancy rate as compared to firm catheters.

Ultrasound guidance is not necessary during easy embryo transfers

PURPOSE

To determine whether the use of ultrasound (US) to guide embryo transfer (ET) in a population previously defined as likely to have easy transfer would change the implantation and pregnancy rates in an ICSI program.

METHODS

A total of 100 patients identified as likely to have easy transfer after mock transfer were divided into two groups: Group I, US-guided ET (N = 50) and Group II, ET without the aid of US (N = 50).

RESULTS

Implantation and pregnancy rates were similar (p = 0.51, p = 0.29) for Group I (19.6%, 42%) and Group II (16.3%, 30%), as also was the abortion rate (p = 0.55) (Group I: 1/21; Group II: 2/15).

CONCLUSION

As long as previous mock transfers are routinely performed during a cycle preceding assisted reproduction and the clinician considers transfer to be easy, ultrasound does not benefit the process of embryo transfer.

Implantation Failure in Assisted Reproduction Technology and a Critical Approach to Treatment

In this article, we review the literature and our personal experience regarding the many factors that appear to influence implantation rate. Oocyte quality, as determined by patient age and aneuploidies, probably plays a major role in RIF. However, a panoply of other factors have been brought under investigation, quite often with contradictory results and additional intriguing questions to be studied. Infections of the vagina, cervix, and endometrium, the role of mucus aspiration and washing of the cervix on transfer, the role of catheter guidance for a correct transfer and potion of embryos, the effect of mock transfer, and the role of hysteroscopy and its timing before transfer procedures are analyzed both as a review of the literature and as opinions and data from our experience. Many of these factors are interlaced and from the apparently simple issue of trauma, to infections and immune modulation of hatching and implantation, a biological continuum can easily be identified. The impact of abnormalities of the immune system and of homeostasis abnormalities is also covered in a brief overview of reported works and our experience. These latter areas probably constitute the common biological background of all other external factors that, however, the skilled must equip themselves for improving implantation success.

Impact des techniques de transfert sur l’implantation

Embryo transfer is an important step in the success of IVF treatment. All efforts should be made to avoid difficult embryo transfers provoking bleeding or uterine contractions. Evaluation before IVF treatment, including a trial transfer and a uterine ultrasonography, should allow one to evaluate the transfer step, anticipate problems, and thus improve treatment. An hysteroscopy can be useful for uterine cavity exploration. It is also important to remove cervical mucus before introduce the transfer catheter. It is essential to deposit embryos as gently as possible during IVF, avoiding manoeuvres that might trigger uterine contractions which could adversely affect the results of this treatment. Soft catheters perform better, and ultrasound-guidance facilitates embryo transfer. Progesterone administration starting on the day of oocyte retrieval induces a decrease in uterine contraction frequency on the day of ET (embryo transfer). Both Wallace and CDD catheters perform similarly. Trial catheterization on the day of ET could prevent most of the unanticipated procedural difficulties during the transfer.

The Impact of Embryo Transfer on Implantation—A Review

Embryo transfer has received little clinical attention and has been, until recently, the most inefficient step in in-vitro fertilization (IVF). In this article, the authors review the literature and their personal experience regarding the process of intrauterine transfer of embryos, which remains the object of much discussion. Factors which appear to influence implantation rates are: contamination of the catheter tip with cervical bacteria, stimulation of uterine contractions during the procedure, the type of catheter, ultrasound guidance during the transfer, and the position of the embryos in the uterine cavity. Easy and atraumatic transfer is essential for successful implantation and the embryos need to be placed in the middle of the cavity, away from the fundus. Knowing, beforehand, the position and length of the uterus can provide better results and may reduce the rate of ectopic pregnancies. Evidence from randomized studies has supported this claim. Despite the number of available studies controlling certain variables, most authors, even using the same catheter, ultrasound guidance and/or a trial transfer use different protocols or similar instruments in different ways. Standardization of the transcervical intrauterine transfer of embryos in a large randomized study is needed before definitive conclusions can be drawn. The goal of improved implantation and pregnancy rates deserve these efforts.

Endometrial lesions caused by catheters used for embryo transfers: a preliminary report

OBJECTIVE

To visualize by microhysteroscopy any possible lesions on the endocervix and endometrium made by the catheters commonly used for embryo transfer (ET).

DESIGN

Prospective descriptive study. Tertiary fertility center (IFER).

PATIENT(S)

Twenty-three infertile patients underwent a mock transfer before a microhysteroscopy during the postovulatory phase (days 2-5 after ovulation) of the cycle with a Tomcat catheter (n = 5), Frydman's catheter (n = 5), Frydman's set (n = 3), or Wallace's catheter (n = 10).

INTERVENTION(S)

Mock ETs and subsequent mycrohysteroscopies.Visualization, description, and documentation of endocervical and endometrial lesions.

RESULT(S)

The lesions in all 23 patients were described and documented (tunnel-like, groove-like, punch-out, crater-like). The Wallace catheter appears to be less traumatic to the endometrium (but it seems that it is important to take care to not pass the internal os with the outer sheath). The Tomcat catheter and the Frydman's set caused the more significant lesions that were observed.

CONCLUSION(S)

In this preliminary study, for the first time endometrial lesions caused by the ET catheters were directly visualized and documented. Some of these observed lesions appear to be capable of compromising the success of ET.

Impact of technical difficulties, choice of catheter, and the presence of blood on the success of embryo transfer--experience from a single provider

PURPOSE

To investigate the impact of technical difficulties, choice of catheter, and the presence of blood during embryo transfer on the results of in vitro fertilization and ICSI.

METHODS

A cohort of 784 consecutive cycles in 655 in vitro fertilization and ICSI patients were studied.

RESULTS

Negotiating the cervix, using the volsellum, presence of blood on the catheter wall or on the cervix did not affect the results. Changing the catheter and blood on the catheter tip reduced the pregnancy (P < 0.05 and P < 0.05) and implantation rates (P < 0.001 and P < 0.01). The Ultrasoft catheter produced higher pregnancy (P < 0.0005) and implantation rates (P < 0.01) compared to the more rigid Frydman catheter.

CONCLUSIONS

Negotiation of the cervix, the use of a volsellum, and the presence of blood on the catheter wall or on the cervix do not affect the results. Changing the catheter and blood on the catheter tip significantly diminish the pregnancy and implantation rates. Soft catheters perform better.

A randomized controlled trial of a soft double lumen embryo transfer catheter versus a firm single lumen catheter: significant improvements in pregnancy rates

BACKGROUND

Embryo transfer has changed little since originally described in 1978. Clinicians rate the type of catheter used as the third most important variable in embryo transfer, but there are no adequately powered randomized trials. We compared the clinical pregnancy rates with the single lumen catheter (TCC) and the double lumen catheter (CC) in a randomized single blind trial.

METHODS

A total of 650 cycles of women from the Adelaide University reproductive medicine units in Australia were included in this trial. Patients were <40 years of age undertaking IVF and embryo transfer. Exclusion criteria were: known uterine abnormality, day 3 FSH >10 IU/l, previous difficult embryo transfer and pre-implantation genetic diagnosis. Cycles were randomized from numbered sealed envelopes immediately prior to embryo transfer with stratification for fresh or frozen cycles.

RESULTS

There was a significantly higher pregnancy rate in the group treated with the CC compared with the TCC catheter [29.6 versus 20.5% per embryo transfer, odds ratio (OR) = 1.63 (95% confidence interval: 1.14-2.30), P = 0.0076]. The point estimate for the OR was similar for fresh and frozen cycles.

CONCLUSIONS

The pregnancy rate was increased by 50% and this justifies the increased cost of the soft double lumen catheter and the training of clinical staff required.

Transvaginal ultrasound-guided embryo transfer improves outcome in patients with previous failed in vitro fertilization cycles

OBJECTIVE

To determine the effect of transvaginal ultrasound-guided ET in IVF cycles performed on patients who had previously failed to conceive from IVF and compare the results to previous cycles where ultrasound guidance was not used.

DESIGN

Retrospective clinical study.

SETTING

Private practice IVF program.

PATIENT(S)

One hundred twenty-nine women undergoing consecutive cycles of IVF where fresh embryos were transferred.

INTERVENTION(S)

Transvaginal ultrasound guidance was used during transfer of embryos.

MAIN OUTCOME MEASURE(S)

Patient age, number of ampules of gonadotropin used, maximum E(2) level, number of oocytes retrieved, number of two pronuclei embryos obtained, number of embryos transferred, mean embryo score, implantation and pregnancy rate.

RESULT(S)

There was no difference in any of the clinical parameters measured in IVF cycles resulting in pregnancy when transvaginal ultrasound-guided ET was used compared to the failed cycles when there was no ultrasound guidance. Of the patients who previously had failed IVF cycles and subsequently had IVF cycles with ultrasound guidance, those who became pregnant had higher mean embryo scores than those who did not become pregnant. Overall implantation and pregnancy rates were higher during the study period when transvaginal ultrasound guidance was used than in the previous 3 years when it was not used.

CONCLUSION(S)

Transvaginal ultrasound-guided ET may be responsible for successful IVF cycles in patients who had previously failed to conceive when embryos were transferred by the clinical touch method. Transvaginal ultrasound guidance may also be responsible for an overall increase in embryo implantation and pregnancy compared to the use of the clinical touch method.

A prospective randomized comparison of the Wallace catheter and the Cook Echo-Tip catheter for ultrasound-guided embryo transfer

OBJECTIVES

To compare the performance of a new coaxial catheter system with an echo-dense tip (Cook Echo-Tip catheter) with a Wallace catheter during ultrasound-guided ET.

DESIGN

Prospective, randomized study.

SETTING

Private academically affiliated infertility center.

PATIENT(S)

Two hundred fifty-one patients undergoing IVF-ET.

INTERVENTION(S)

The patients underwent ultrasound-guided ET by a single physician with a standardized technique alternately using one of the two catheters.

MAIN OUTCOME MEASURE(S)

Implantation rates, pregnancy rates, ease of transfer, visualization, and status of catheter tip.

RESULT(S)

The echo-dense tip of the Cook Echo-Tip catheter was consistently seen with ultrasound guidance, minimizing the need for catheter movement to identify the tip. Implantation rate (30% vs. 35%), clinical pregnancy rate (57% vs. 55%), and ongoing pregnancy rate (49% vs. 47%) were similar in both groups.

CONCLUSION(S)

The Cook Echo-Tip catheter with its echogenic tip simplifies ultrasound-guided ET, but pregnancy success rates are similar to those obtained when a Wallace catheter is used.

A Wallace malleable stylet for difficult embryo transfer in an in vitro fertilization program: a case-control study

BACKGROUND

The aim of the study was to evaluate the impact of using a Wallace malleable stylet in combination with an Edwards-Wallace embryo replacement catheter in case of difficult embryo transfer (ET).

METHODS

A retrospective case-control study was used. The standard ET procedure at the clinic was to use a single tooth tenaculum, and a speculum to straighten the cervical canal prior to inserting the Edwards-Wallace embryo replacement catheter. In 205 of 2041 (10%) fresh ET difficulties were experienced during ET and a Wallace malleable stylet was used to place the outer catheter sheath correctly. This stylet transfer group was compared with a control transfer group of 410 ET performed just before and after each stylet transfer.

RESULTS

No differences in number of transferred embryos, cleavage stage, or embryo morphology score were found between the two groups. We found no differences in implantation rates (20.7 and 19.2% [95% confidence interval (CI) 0.8-1.5]) or delivery rates (29.3 and 25.4% [CI 0.8-1.8]) between the study and control group.

CONCLUSION

Using a Wallace malleable stylet in combination with an Edwards-Wallace embryo replacement catheter in case of difficult ET has no negative impact on implantation and delivery rates.

Clinical practice of embryo transfer

In this review, several embryo transfer methods are considered, together with factors involved in achieving an effective transfer. The approach most used is transcervical intrauterine transfer. This is described in detail, together with the many variables influencing success, e.g. technical ability and training of personnel, catheter choice, value of a previous 'dummy transfer' and the need to minimize trauma during transfer and so prevent damage to the uterine lining, bleeding and uterine contractions. These factors can each negatively impact on pregnancy rates. Emphasis is put on quality, developmental stage and number of embryos to be transferred to limit multiple pregnancies and their unwanted side-effects. Culture to blastocyst stages and single embryo transfer when optimal quality embryos are available are discussed as means of avoiding multiple pregnancies. Reference is made to embryo cryopreservation and fertility following frozen embryo transfer. Other techniques, such as ultrasound-controlled transcervical intrauterine transfer, and ultrasound-controlled transmyometrial transfer, are reviewed. More invasive procedures, generically grouped as surgical embryo transfer, including gamete intra-Fallopian transfer (GIFT), zygote intra-Fallopian transfer (ZIFT), pronuclear stage transfer and embryo intra-Fallopian transfer (EIFT), are also described. These techniques had a place in IVF when the need to apply assisted reproductive techniques exceeded the capacity of most laboratories, but not today thanks to refined laboratory technology and improved understanding of implantation. Alternative assisted reproductive technologies, such as direct intra-follicular insemination (DIFI), Fallopian spermatic perfusion (FSP), peritoneal oocyte stage and sperm transfer and intra-vaginal culture (IVC), are mentioned briefly.

The effect of ease of transfer and type of catheter used on pregnancy and implantation rates in an IVF program

PURPOSE

To test the effects of type of embryo transfer catheter, transfer difficulty, and observations after the transfer procedure on pregnancy and implantation rates in an IVF programme.

METHODS

Patients were prepared for IVF using standard protocols. Embryo transfer was performed using either Edwards-Wallace or TDT catheter. The difficulty of transfer was graded by a clinician and biologist. Blood observed inside the catheter after the transfer procedure was scored as endometrial damage. Pregnancy and implantation rates were scored.

RESULTS

Type of embryo transfer catheter and the observation of blood did not significantly affect pregnancy and implantation rates when transfer was performed by a single operator.

CONCLUSIONS

In the hands of experienced, skilled operators, neither choice of transfer catheter and difficulty of transfer nor observations of blood on the transfer catheter caused any significant reduction in outcome to the patient.

Embryo transfer: techniques and variables affecting success

OBJECTIVE

To review the literature on the variables affecting embryo transfer success or failure and to define technical factors associated with optimal outcome.

DESIGN

Literature review.

RESULTS

Avoidance of blood, mucus, bacterial contamination, excessive uterine contractions, and trauma to the endometrium is associated with optimal pregnancy and implantation rates after transcervical embryo transfer. A trial transfer, ultrasonographic guidance, and use of "soft" catheters appear to facilitate successful embryo transfer.

CONCLUSION

An understanding of the variables associated with embryo transfer success together with adherence to techniques shown to facilitate atraumatic embryo transfer will enhance the efficiency of IVF by maximizing embryo implantation.

Ultrasound-guided embryo transfer maximizes the IVF results on day 3 and day 4 embryo transfer but has no impact on day 5

BACKGROUND

The use of ultrasound-guided embryo transfer has been reported to affect success rates in some centres but not others. In a prospective study, we examined the influence of ultrasound guidance in embryo transfer performed on different days after oocyte retrieval.

METHODS

Two different methods of embryo transfer were evaluated in 1069 consecutive transfers. The ultrasound-guided embryo transfer was used in 433 cases, whereas 636 embryo transfers were performed with the tactile assessment ('clinical feel') method.

RESULTS

Ultrasound-guided embryo transfer yielded a higher overall pregnancy rate than the 'clinical feel' approach, 47 versus 36% (P < 0.001). This difference was statistically significant where embryos were transferred after 3 or 4 days of culture, 45.9 versus 37.1% (P = 0.001) and 42.3 versus 27% (P = 0.035) respectively but not significant (P = 0.112) on day 5 embryo transfer (56.3 versus 45.7%). Likewise, the implantation rate was significantly different between the two groups on day 3 and 4 embryo transfer, 23.3 versus 15.8% (P < 0.01) and 21.6 versus 15.7% (P < 0.05%) respectively but no statistical difference was noted on day 5 embryo transfer, 26.7 versus 23.6%.

CONCLUSION

Ultrasound assistance in embryo transfer on day 3 and 4 significantly improved pregnancy rates in IVF but had no impact on day 5.

Ultrasound-guided embryo transfer: immediate withdrawal of the catheter versus a 30 second wait

It is essential to deposit embryos as gently as possible during IVF, avoiding manoeuvres that might trigger uterine contractions which could adversely affect the results of this treatment. The time during which the embryo transfer catheter remains in the cervical canal might be related to stimulation of contractions. This study investigates the influence that the time interval before withdrawal of the catheter after ultrasound (US)-guided embryo deposit might have on the pregnancy rate in patients under IVF cycles. A total of 100 women about to undergo transfer of at least two optimal embryos was studied. The women were prospectively randomized into two groups: (i) slow withdrawal of the catheter immediately after embryo deposit (n = 51); and (ii) a 30 s delay before catheter withdrawal (n = 49). The pregnancy rates for transfer in the two groups were 60.8 and 69.4% respectively, with no significant differences. There were no statistically significant differences in pregnancy rates between the two patient groups. The results indicate either that the waiting interval was insufficient to detect differences, or that the retention time before withdrawing the catheter is not a factor that influences pregnancy rate.

A postal survey of embryo transfer practice in the UK

In this postal survey a questionnaire was sent to all unit directors in the UK to determine their attitudes to the factors influencing embryo transfer practice. They were requested to rate each step on a scale of 1-10, where 1 was irrelevant and 10 very important. A total of 80 practitioners from 40 units replied. Over 50% of the corresponding practitioners were consultants, 33% were middle-grade clinicians, and 12% were infertility nurse specialists. The factor that got the highest rating was the need for a standardized protocol for all unit staff regarding embryo transfer technique. The second critical factor voted by the respondents was the presence of blood on the embryo transfer catheter. Not touching the uterine fundus was deemed to be the third most important factor while the type of embryo transfer catheter used was a very close fourth. Prolonged bed rest following embryo transfer was voted the least important factor to influence the outcome. The wide variations in practice and choice of catheters encountered in this survey are indications of the divided opinion and lack of concrete evidence on which to base any firm decisions. The need for large clinical studies to assess clearly whether higher pregnancy rates will result from modifications in embryo transfer practice is highlighted.