We wanted to learn whether ultrasound-guided embryo transfer (UGET) improves pregnancy outcomes compared with clinical touch. The traditional method of embryo transfer, clinical touch relies on the clinician's tactile senses to judge when the transfer catheter is in the correct position.
The inability of some women undergoing fertility treatment to achieve a live birth may be due to a number of factors, such as lack of good-quality embryo/s, problems with the uterus, or the transfer technique itself. This review looks at one aspect of the transfer technique, whether ultrasound guidance improves pregnancy outcomes compared with clinical touch (clinical judgement without any technical assistance).
We found 21 randomised controlled trials that compared UGET with clinical touch in a total of 6218 women. The evidence is current to May 2015.
Live birth/ongoing pregnancies were increased for the ultrasound-guided group compared with the clinical touch group, based on low-quality evidence. We estimate that for women with a chance of a live birth/ongoing pregnancy of 23% using clinical touch, this would increase to between 28% and 33% using UGET. Data for live birth should be interpreted carefully, as differences between the studies make drawing a conclusion difficult. The evidence suggests that in studies that used the same brand of transfer catheter in both the ultrasound-guided and the clinical touch groups, ultrasound guidance was linked to an increase in the chance of a live birth. There was no evidence that the risk of harm using UGET, including miscarriage, ectopic pregnancies, and multiple pregnancies, is any different than when clinical touch is used to guide the embryo transfer.
Quality of the evidence
The quality of the evidence for live birth/ongoing pregnancy was low due to poor reporting of study methods and inconsistency in trial results.
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.
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.
To determine whether ultrasound guidance compared with clinical touch improves pregnancy outcomes in women undergoing embryo transfer during ART cycles.
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.
We included only randomised controlled trials.
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.
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; I2 = 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; I2 = 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.