Ultrasound-guided embryo transfer

Abstract

ET success rates can be improved dramatically by paying attention to technique (Box 1). The potential negative factors that need to be avoided include Box 1. Suggested ET protocol for maximizing success rates. Routine transfers. Trial transfer - precycle or at time of retrieval. Transabdominal ultrasound guidance with full bladder. Removal of excess cervical mucus with a syringe, plastic cotton swab, or cervical lavage with culture media. Soft catheter, 30 pL volume, embryos in last 10 μL of fluid, continuous fluid column. Gentle technique during insertion of catheter tip and negotiating it through the cervical canal. Real-time monitoring of catheter tip by way of ultrasound (avoid disrupting endometrium, avoid touching fundus). Gentle injection of embryos in the middle one third of the cavity as confirmed by ultrasound. Slow withdrawal of catheter with a rotating motion to dislodge any cervical mucus. Inspection of catheter tip by embryologist for retained embryos, blood, or mucus. Difficult transfers. This technique should be used promptly if there is difficulty in negotiating the cervical canal with the soft catheter. Withdraw loaded catheter and give to assistant (usually the embryologist). Replace it with a malleable stylette whose tip has been bent to conform to the direction of the cervical canal as visualized on ultrasound. Insert the stylette until the level (but not beyond) of the internal os. level of the internal os. Thread the inner noodle of the soft catheter, which is loaded with the embryos, through the outer sheath until its tip is seen in the middle one third of the uterine cavity. Complete ET as per routine. (1) initiation of uterine contractility that may lead to an immediate or delayed expulsion of the embryos; (2) the presence of cervical mucus that can plug the tip of the catheter or entangle the embryos and drag them out during withdrawal of the catheter; and (3) proper placement of the embryos into the middle third of the uterine cavity [2]. Ultrasound-guidance during ET is a valuable tool that can improve success rates. Direct observation of the catheter tip can be useful, especially in patients with variations of normal anatomy (eg, long cervix, acutely anteverted or retroverted uteri). This minimizes the possibility of transferring embryos in a blind passage in the cervix, detects when the catheter tip is folding back on itself, and makes it possible to avoid subendometrial transfer of the embryos [46]. We use this technique at our Center; our current pregnancy rates are the highest they have been since the inception of the IVF program more than 15 years ago [48].