Transfer of embryos into the uterus: how much do technical factors affect pregnancy rates?

Transabdominal ultrasound-guided embryo transfer does not increase pregnancy rates in oocyte recipients

OBJECTIVE

To determine whether transabdominal ultrasound guidance during embryo transfer (ET) is a useful tool for increasing pregnancy rates in patients undergoing oocyte donation.

DESIGN

Prospective, randomized, controlled trial.

SETTING

In vitro fertilization academic center.

PATIENT(S)

Three hundred seventy-four infertile patients undergoing oocyte donation.

INTERVENTION(S)

Transabdominal ultrasound-guided ET.

MAIN OUTCOME MEASURE(S)

We measured the pregnancy rate and implantation rate after transabdominal ultrasound-guided ET versus the rates in a control group who did not receive transabdominal ultrasound-guided ET.

RESULT(S)

Clear visualization at ultrasound during ET was achieved in 90.8% of the patients who had ultrasound-guided ET. A similar number of easy transfers were performed in both the ultrasound-guided and the control groups (84.5% vs. 86.6%). The pregnancy rate was comparable between the groups (59.9% ultrasound vs. 55.1% control), as was the implantation rate (30.6% ultrasound vs. 26.3% control). No differences were found in the miscarriage rate (10.7% ultrasound vs. 9.1% control) or in the multiple pregnancy rate (21.4% ultrasound vs. 22.5% control). Although all ectopic pregnancies occurred in the group that did not receive ultrasound guidance, the differences were not statistically significant (0 vs. 2.7%).

CONCLUSION(S)

We could not show any benefit in terms of pregnancy rate in oocyte recipients for whom ET was performed under direct transabdominal ultrasound visualization of the endometrial cavity. There was a lower ectopic pregnancy rate when ultrasound guidance was used, but this rate was not statistically significant in comparison with the pregnancy rate without ultrasound guidance.

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.

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.

Transvaginal ultrasound-guided embryo transfer improves pregnancy and implantation rates after IVF

BACKGROUND

Attempts are constantly being made to improve clinical pregnancy rates after IVF and embryo transfer. Since November 1998, we have gradually been adopting transvaginal ultrasound guidance during embryo transfer. We retrospectively examined the efficacy of this method on pregnancy and implantation rates.

METHODS

The results of 846 cycles from our IVF-embryo transfer programme were analysed and comparisons were made between those carried out using ultrasound guidance and those by the clinical touch method.

RESULTS

Higher pregnancy and implantation rates (28.9 and 15.2% respectively) were found in the group using the transvaginal ultrasound guidance during embryo transfer compared with those in the group using the clinical touch method (13.1 and 7.0% respectively). The differences were statistically significant (P < 0.01). There was no significant difference in ectopic pregnancy rates between the two groups.

CONCLUSION

The use of transvaginal ultrasound-guided embryo transfer significantly improved both pregnancy and implantation rates. Although technically difficult, we suggest its use may maximize the chances of achieving a successful pregnancy outcome.

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.

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.

The choice of embryo transfer catheter affects embryo implantation after IVF

OBJECTIVE

Comparison of two transfer catheters in an IVF program.

DESIGN

Prospective, randomized clinical study.

SETTING

A private tertiary care center for ART.

PATIENT(S)

66 patients < 38 years of age undergoing IVF and/or ICSI.

INTERVENTION(S)

Patients were randomly assigned to undergo ET using the Tomcat catheter (n = 32) or the TDT catheter (n = 34).

MAIN OUTCOME MEASURE(S)

Primary outcome measures were implantation and pregnancy rates. Secondary outcome measures were contamination with blood and/or mucus on the tip of the catheter, cramping or patient discomfort, and time required to complete ET.

RESULT(S)

Use of the Tomcat catheter resulted in significantly higher implantation (25.2% vs. 8.4%) and clinical pregnancy rates (47% vs. 14.7%) compared with the TDT catheter. All secondary outcome measures were similar for both catheters.

CONCLUSION(S)

The choice of ET catheter may affect the success of IVF-ET cycles. Use of the Tomcat catheter compared with the TDT catheter seems to result in significantly better efficiency of the ET procedure and is more cost effective.

Three-dimensional ultrasound in embryo transfer

OBJECTIVE

To examine the feasibility of using three-dimensional (3D) ultrasound (US) guidance in routine embryo transfer (ET) procedures.

METHODS

Seventy-five ETs were performed using a 3D US scanner to locate the catheter tip in the uterine cavity.

RESULTS AND CONCLUSION

Three-dimensional ultrasound could show the exact position of the tip of the catheter in the uterine cavity quickly enough in most cases. It should be used in ET for seeking an optimal transfer area in the uterine cavity to assist in achieving high success rates and less complications.

Pregnancy rates after embryo transfer depend on the provider at embryo transfer

OBJECTIVE

To evaluate the effect of individual providers on pregnancy outcome after embryo transfer.

DESIGN

Retrospective data analysis.

SETTING

University-based tertiary-care assisted reproductive technology program with 10 physician-providers.

PATIENT(S)

Six hundred and seventeen women who underwent 854 fresh embryo transfers between January 1996 and January 1999.

INTERVENTION(S)

Pregnancies after embryo transfer were recorded for each provider.

MAIN OUTCOME MEASURE(S)

Establishment of a clinical pregnancy.

RESULT(S)

Three hundred ninety-three clinical pregnancies resulted from 854 embryo transfers, for an overall clinical pregnancy rate of 46.0% per embryo transfer. Three hundred forty-seven (40.6%) pregnancies were ongoing. The clinical pregnancy rate varied significantly between providers: for example, 17.0% (47 transfers) vs. 54.3% (57 transfers) (P<.05). Similarly, the ratio of high-grade embryos required to produce a gestational sac differed between providers. The number or quality of embryos transferred did not differ significantly.

CONCLUSION(S)

Significant differences were observed in pregnancy rates after embryo transfer done by different providers, suggesting that embryo transfer technique may influence pregnancy outcome in assisted reproductive technology.

Embryo transfer under ultrasound guidance improves pregnancy rates after in-vitro fertilization

Between October 1998 and January 1999, we examined the influence of ultrasound guidance in embryo transfer on pregnancy rate in 362 patients from our in-vitro fertilization (IVF)-embryo transfer programme. These patients were prospectively randomized into two groups: 182 had ultrasound-guided embryo replacement, and 180 had clinical touch embryo transfer. There were no statistically significant differences between the two groups with respect to age, cause of infertility and in the characteristics of the IVF cycle. The pregnancy rate was significantly higher among the ultrasound-guided embryo transfer group (50%) compared with the clinical touch group (33.7%) (P < 0.002). Furthermore, there was also a significant increase in the implantation rate: 25.3% in the ultrasound group compared with 18.1% in the clinical touch group (P < 0.05). In conclusion, ultrasound assistance in embryo transfer significantly improved pregnancy and implantation rates in IVF.

Ultrasound-guided soft catheter embryo transfers will improve pregnancy rates in in-vitro fertilization

Attempts to improve clinical pregnancy rates after in-vitro fertilization (IVF) and embryo transfer are constantly being made. Two changes in technique of embryo transfer of potential clinical importance were evaluated over two contiguous time periods in order to observe any corresponding change in clinical pregnancy (CP) rate per transfer: (i) embryo transfer catheter; (ii) ultrasound guidance. Catheter choices were hard: Tefcat, Tom Cat, or Norfolk; or soft: Frydman or Wallace. Ultrasound visualization was considered to be excellent/good when the catheter could be followed from the cervix to the fundus by transabdominal ultrasound with retention of the embryo-containing fluid droplet; fair/poor if visualization could not document the sequence of events. Embryo transfers were performed in 518 cycles. CP rates per transfer using soft and hard catheters was 36 and 17% (P < 0.000) respectively. CP rates per transfer for transfers performed with and without ultrasound guidance were 38 and 25% (P < 0.002) respectively. A statistically significant difference was also noted when visualization ranks were compared. CP rates per transfer in all excellent/good ultrasound-guided transfers was 41.5 versus 16.7% for fair/poor transfers (P < 0.038). In conclusion, performance of embryo transfer with a soft catheter under ultrasound guidance with good visualization resulted in a significant increase in clinical pregnancy rates.

Ultrasound guided embryo transfer significantly improves pregnancy rates in women undergoing oocyte donation

OBJECTIVES

Recent reports suggest ultrasound (US) guided embryo transfer (ET) improves pregnancy rates. Using the ovum donation model to eliminate confounding variables, we assessed the impact of US guided ET on pregnancy rates, implantation rates, and multiple gestation rates.

METHODS

All women who underwent IVF-ET cycles using donated oocytes from November 1997 to September 1998 (n = 137) were evaluated retrospectively. ET from November 1997 to April 1998 were performed without US, while all ET from May 1998 to September 1998 were performed using transvaginal or transabdominal US. ET was further categorized as easy or difficult. Difficult ET was defined as requiring at least two attempts and/or the presence of blood on the catheter and/or > 5 min.

RESULTS

Pregnant patients (n = 73) were similar with respect to the number and morphology of the embryos transferred compared to non-pregnant patients (n = 65). US guidance significantly improved implantation and pregnancy rates in cycles with easy transfers [28.8 vs. 18.4% and 63.1 vs. 36.1%, respectively (P < 0.05)] without impacting multiple pregnancy rates.

CONCLUSION

US guided ET is simple and reassuring and appears to significantly improve pregnancy outcomes in ovum donation cycles by optimizing the placement of embryos.