Ultrasonographic-guided embryo transfer does not enhance pregnancy rates compared with embryo transfer based on previous uterine length measurement

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.

Accuracy and efficacy of embryo transfer based on the previous measurement of cervical length and total uterine length

PURPOSE

Aim of the study was to examine the accuracy of embryo transfer based on the previous measurement of cervical length and total uterine length.

METHODS

The study has taken place in an academic-assisted reproduction clinic. 248 patients with infertility requiring IVF/ICSI treatment have been included. All patients underwent IVF/ICSI cycles with antagonist protocol and were treated with controlled ovarian stimulation using recombinant FSH (100-400 IU/day). On the day of oocyte retrieval, all patients were given vaginally natural micronized progesterone in a dose of 200 mg/tds. All patients had transvaginal ultrasound measurement of cervical length and endometrial cavity length prior to embryo transfer and measurement of embryo distance (intrauterine air bubbles) from fundal surface of uterine cavity and internal cervical os immediately after embryo transfer. Embryo transfer was performed on days 2-3. Primary outcome was to estimate the accuracy of embryo transfer based on the measurement of the embryo distance from middle of uterine cavity after embryo transfer and secondary outcome was to assess the effect of embryo distance from uterine fundus and internal cervical os to clinical pregnancy rate.

RESULTS

The clinical pregnancy rate was 42.7%. The mean embryo distance from the middle of endometrial cavity was 0.48 ± 0.02 cm, the mean embryo distance from the uterine fundus was 0.88 ± 0.32 cm, and from the internal cervical os was 1.67 ± 0.45 cm. Multiple regression analysis showed that the embryo distance from middle of cavity was related to endometrial cavity length and to the embryo distance from the fundus and it was not related to Cx length, total uterine length, embryo distance from internal Cx os, and embryo transfer length.

CONCLUSIONS

Embryo transfer with the previous measurement of total uterine length and estimation of embryo transfer length can be performed with very good accuracy by a single operator.

Large randomized trial comparing transabdominal ultrasound-guided embryo transfer with a technique based on uterine length measurement before embryo transfer

OBJECTIVE

To compare in a randomized, non-inferiority trial the embryo transfer (ET) technique based on uterine length measurement before transfer (ULMbET) with transabdominal ultrasound-guided embryo transfer (TA-UGET) in a large population of patients undergoing in-vitro fertilization (IVF).

METHODS

Patients undergoing IVF with ET with cleaving fresh embryos were randomized to receive ULMbET or TA-UGET. The transfer of one to three embryos on day 2-3 of culture was performed using a soft catheter either under transabdominal ultrasound guidance (TA-UGET group) or after measurement of the uterine cavity by transvaginal ultrasound and calculation of the discharge site (ULMbET group). The primary outcome measures were clinical pregnancy rate, ongoing pregnancy rate and implantation rate, and secondary outcomes included patient discomfort during ET.

RESULTS

A total of 1648 patients undergoing IVF were randomized to receive ULMbET (n = 828) or TA-UGET (n = 820) and were included in the analysis. Comparable clinical pregnancy rate (38.2% vs 38.9%), implantation rate (24.8% vs 25.2%) and ongoing pregnancy rate (33.1% vs 34.8%) were observed in ULMbET and TA-UGET groups. The discomfort intensity score and the proportion of patients with moderate-to-severe discomfort during ET were significantly higher in the TA-UGET group (2.6 vs 1.5 visual analog scale points and 19.8% vs 1.2%; P = 0.045 and P = 0.003, respectively).

CONCLUSION

The ULMbET technique leads to IVF results comparable to those obtained with UGET, but is better tolerated than is TA-UGET and is technically easier to perform for a single operator. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.

Assessment of pregnancy-associated, within-woman change in uterine length

OBJECTIVE

To evaluate how absolute uterine length changes as a result of pregnancy.

METHODS

Longitudinal repeated-measures study of all women presenting to a university-affiliated clinic for uterine sounding prior to in vitro fertilization (IVF) who went on to deliver at term and return for repeat measurement from 2002 to 2012. Change in uterine length was assessed by the Wilcoxon signed-rank test.

RESULTS

Among 495 women, mean pregnancy-associated change in uterine length was 0.0 cm (SD ± 0.7, p = 0.84), with 31% of women experiencing no change and 75% of women experiencing a change ≤0.5 cm. Mean uterine lengths at pre-cycle and repeat measurement were 7.2 cm (SD ± 0.7) and 7.2 cm (SD ± 0.7) with medians of 7.0 cm (IQR 7.0-7.5) and 7.0 cm (IQR 6.8-7.8), respectively. Change in uterine length did not vary by gestational number or within time interval between measurements (all p > 0.5).

CONCLUSIONS

There was no difference in uterine length before and after term pregnancy. The finding of minimal variation in uterine length both across and within women suggests uterine length may be relatively stable such that patients undergoing IVF after term IVF pregnancy may not require repeat measurement. Future studies might assess pregnancy-associated sonographic changes in uterine volume and the relationship between uterine length and IVF outcomes.