Editing Embryo transfer (section)

== Procedure ==
The embryo transfer procedure starts by placing a speculum in the vagina to visualize the cervix, which is cleansed with saline solution or culture media.  A transfer catheter is loaded with the embryos and handed to the clinician after confirmation of the patient's identity. The catheter is inserted through the cervical canal and advanced into the uterine cavity.<ref>{{Cite web |url=https://www.youtube.com/watch?v=kvQZA7EWwmk  |archive-url=https://ghostarchive.org/varchive/youtube/20211213/kvQZA7EWwmk |archive-date=2021-12-13 |url-status=live|title=Embryo Transfer |date=25 March 2015 |publisher=Dr. John Jain on Youtube |last=Jain |first=John |access-date=17 December 2015}}{{cbignore}}</ref> Several types of catheters are used for this process, however, there is good evidence that using a soft vs a hard transfer catheter can increase the chances of clinical pregnancy.<ref>{{cite journal |last=Tayler |first=Bede |title=Interventions to optimize embryo transfer in women undergoing assisted conception: a comprehensive systematic review and meta-analyses |journal=Human Reproduction Update |year=2022 |volume=28 |issue=4 |pages=480–500 |doi=10.1093/humupd/dmac009|pmid=35325124 |pmc=9631462 }}</ref>

There is good and consistent evidence of benefit in ''ultrasound guidance'',<ref name=mains /> that is, making an abdominal ultrasound to ensure correct placement, which is 1–2&nbsp;cm from the uterine fundus.<ref>{{Cite journal |journal=Human Reproduction Update |year = 2022|doi=10.1093/humupd/dmac009|pmid = 35325124|last1 = Tyler|first1 = B.|last2 = Walford|first2 = H.|last3 = Tamblyn|first3 = J.|last4 = Keay|first4 = S. D.|last5 = Mavrelos|first5 = D.|last6 = Yasmin|first6 = E.|last7 = Al Wattar|first7 = B. H.|title=Interventions to optimize embryo transfer in women undergoing assisted conception: A comprehensive systematic review and meta-analyses | volume=28 | issue=4 | pages=480–500 | pmc=9631462 }}</ref> There is evidence of a significant increase in clinical pregnancy using ultrasound guidance compared with only "clinical touch", as well as performing the transfer with hyaluronic acid enriched transfer media.<ref name="OUP accepted manuscript">{{Cite journal |date=2022 |title=OUP accepted manuscript |url=https://doi.org/10.1093/humupd/dmac009 |journal=Human Reproduction Update |doi=10.1093/humupd/dmac009 |pmid=35325124 |issn=1355-4786|last1=Tyler |first1=B. |last2=Walford |first2=H. |last3=Tamblyn |first3=J. |last4=Keay |first4=S. D. |last5=Mavrelos |first5=D. |last6=Yasmin |first6=E. |last7=Al Wattar |first7=B. H. |volume=28 |issue=4 |pages=480–500 |pmc=9631462 }}</ref> Anesthesia is generally not required. Single embryo transfers in particular require accuracy and precision in placement within the uterine cavity. The optimal target for embryo placement, known as the maximal implantation potential (MIP) point, is identified using 3D/4D ultrasound.<ref>{{cite journal | vauthors = Gergely RZ, DeUgarte CM, Danzer H, Surrey M, Hill D, DeCherney AH | title = Three dimensional/four dimensional ultrasound-guided embryo transfer using the maximal implantation potential point | journal = Fertility and Sterility | volume = 84 | issue = 2 | pages = 500–3 | date = August 2005 | pmid = 16084896 | doi = 10.1016/j.fertnstert.2005.01.141 | doi-access = free }}.</ref> However, there is limited evidence that supports deposition of embryos in the midportion of the uterus.<ref name=mains /><ref name="OUP accepted manuscript"/>

After insertion of the catheter, the contents are expelled and the embryos are deposited. Limited evidence supports making trial transfers before performing the procedure with embryos.<ref name=mains /> After expulsion, the duration that the catheter remains inside the uterus has no effect on pregnancy rates.<ref>{{cite journal | vauthors = Sroga JM, Montville CP, Aubuchon M, Williams DB, Thomas MA | title = Effect of delayed versus immediate embryo transfer catheter removal on pregnancy outcomes during fresh cycles | journal = Fertility and Sterility | volume = 93 | issue = 6 | pages = 2088–90 | date = April 2010 | pmid = 20116786 | doi = 10.1016/j.fertnstert.2009.07.1664 | doi-access = free }}</ref> Limited evidence suggests avoiding negative pressure from the catheter after expulsion.<ref name=mains /> After withdrawal, the catheter is handed to the embryologist, who inspects it for retained embryos.

In the process of [[zygote intrafallopian transfer]] (ZIFT), eggs are removed from the woman, fertilised, and then placed in the woman's fallopian tubes rather than the uterus.
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