|
Middle East Fertility Society Journal
Middle East Fertility Society
ISSN: 1110-5690
Vol. 9, Num. 3, 2004, pp. 202-204
|
Middle East Fertility Society Journal, Vol. 9, No. 3, 2004, pp.
202-204
DEBATE
Embryo
transfer techniques: what affects the results?
Comment by:Ragaa Mansour, M.D., Ph.D.Cairo, Egypt
Code Number: mf04036
The technique of embryo transfer (ET) is the last and most crucial step
determining the outcome of In-Vitro Fertilization. Great attention and time
should be given to the ET procedure. Several factors can optimize the success
of this procedure:
First: Careful evaluation of the uterus:
It has been demonstrated that performing a dummy embryo transfer before
the IVF cycle significantly improves the pregnancy rate (1). The trial ET
can be done before the IVF cycle or immediately before the actual ET (2).
It is important to evaluate the length and direction of the uterine cavity.
It is also important to choose the most suitable ET catheter. Dummy ET helps
to discover any unanticipated difficulty in entering the uterine cavity
resulting from such things as cervical fibroids, anatomical distortion of
the cervix from previous surgery, or congenital anomalies and pin-point
external os. If difficulty is diagnosed, cervical dilatation before ovarian
stimulation is advisable.
Ultrasonography (US) is another valuable way of evaluating the uterine
cavity. It gives precise information about the degree of the cervico-uterine
angle, and the length of both the cervix and uterine cavity. US is very
important for diagnosing fibroids that may be encroaching on the uterine
cavity or distorting the cervical canal. It is recommended to revise the
US picture before the ET procedure and to consider it as a map or a guide.
Second: Avoiding the initiation of uterine contractility:
The presence of endometrial movements has been recognized by several investigators
(3-5). Immediate or delayed expulsion of the embryos has always been of
major concern in assisted reproduction (6-9).
Some precautions can be taken to avoid the initiation of uterine contractions.
As a general rule, ET should be a simple and painless procedure. Gentle
manipulation should be the rule throughout the procedure. Holding the cervix
with a volsellum should by completely avoided except in rare cases. It has
been demonstrated that the use of tissue forceps to hold the cervix can
trigger uterine contractions (10). The use of soft catheters should be the
rule except when it can not be introduced. Touching the fundus should be
avoided as it was demonstrated that it initiated strong random waves in
the fundal area and from the fundus to the cervix (11).
Third: Removing the cervical mucus:
Cervical mucus can cause some obstacles in proper embryo replacement. It
can plug the tip of the catheter, causing difficulty in delivering the embryos
inside the uterine cavity, especially since such a small volume of culture
media is injected with the embryos.
Moreover, the embryos can stick to the cervical mucus around the catheter and
be dragged outside during the withdrawal of the catheter. The mucus may also
interfere with implantation if pushed or injected into the uterine cavity. It
has been demonstrated that removing the cervical mucus before a Methylene Blue
dummy transfer significantly reduced the extrusion of the dye (9). It was also
demonstrated that embryos were much more likely to be retained when the ET catheter
was contaminated with blood or mucus (12).
Fourth: Proper placement of the embryos:
It is absolutely essential to be sure that the catheter has passed the internal
cervical os and entered the uterine cavity. Soft catheters can be misleading,
as they can curve inside the cervical canal. A simple test that can be done
to ensure that the soft catheter has passed the internal os and not simply
bent inside the cervical canal is to rotate the catheter 360o. If
it recoils, it means that it is curved inside the cervical canal.
One of the most important causes for the prevention of the catheter to pass
the internal os is the acute angle between the uterine cavity and the cervical
canal. It simply causes a lack of alignment between the catheter (straight)
and the utero-cervical canal (curved or angulated). A simple procedure of curving
the catheter will overcome this problem. It has been demonstrated that molding
the ET catheter according to the utero-cervical angle measured by US increased
the implantation and clinical pregnancy rates (13). Straightening the Utero-Cervical
angle can be achieved by a full bladder (14). This effect is being achieved
indirectly by performing embryo transfer under US guidance. In some cases a
more rigid catheter is needed to pass the internal os. In rare cases the cervix
has to be held by a volsellum in order to stabilize the uterus. However, it
is important to realize that holding the cervix with a volsellum leads to the
release of oxytocin (15) and it is painful and should be done under general
anaesthesia.
One possible reason for retained embryos is the position of the embryo in the
catheter. Small volumes of < 40 (L are preferable, but it is important to
aspirate 20 (L of fluid first then the embryos are aspirated second. This will
ensure enough volume to push out the embryos. In the mean time, it is recommended
once the injection is done to keep the pressure on the plunger of the syringe
until withdrawal of the catheter (16). It is also important to withdraw the catheter
slowly to prevent the creation of a negative pressure. The use of US guidance
for ET was described
by various IVF programs (17, 18).
It has been proven useful in women with previously difficult ET (19). It has
also been found to be simple and reassuring and significantly improved pregnancy
rates by optimizing the placement of the embryos (20-22). However, other studies
found no significant difference between US guidance and clinical touch ET (19,23).
It depends on the experience of the clinician providing the embryo transfer.
In extremely rare cases it is difficult or even impossible to pass the catheter
inside. It could be due to anatomical distortion of the cervix by previous
surgery or the presence of fibroids or congenital anomalies. For these cases,
stiffer systems may be used (1,2). In rare cases trans-myometerial surgical
ET can be performed (24-26).
Fifth: Minimizing embryo expulsion:
In a prospective randomized study it has been demonstrated that applying a
gentle mechanical pressure on the portiovaginalis of the cervix using the
vaginal speculum significantly improved the implantation and clinical pregnancy
rates (27). After introducing the ET catheter, the screw of the vaginal speculum
was loosened so that the two values of the speculum would collapse on the portiovaginalis,
then the embryos were ejected.
In conclusion several precautions should be taken to optimize the ET technique.
The most important is to avoid the initiation of uterine contractility. This
can be achieved by using soft catheters, gentle manipulation, and avoid touching
the fundus. Proper evaluation of the uterine cavity and uterocervical angulation
is very important, and can be done by performing dummy ET and US. Removal of
cervical mucous is another important factor. Finally one has to be absolutely
sure that the catheter passed the internal cervical os.
REFERENCES
- Mansour R, Aboulghar M and Serour G. Dummy embryo transfer a technique that
minimizes the problems of embryo transfer and improves the pregnancy rate
in human in vitro fertilization. Fertil Steril 1990; 54: 678-681.
- Sharif K, Afnan M and Lenton W. Mock embryo transfer with a full-bladder
immediately before the real transfer for in-vitro fertilization treatment:
the Birmingham experience of 113 cases. Hum Reprod 1995; 10: 1715-8.
- Brinholz JC. Ultrasound visualization of endometrial movements. Fertil Steril
1984; 41: 157-158.
- Ijland MM, Evers JL, DunselmanGA, van Katwijk C, Lo CR and Hoogland HJ. Endometrial
wavelike movements during the menstrual cycle. Fertil Steril 1996; 65: 746-9.
- Kunz G and Leyendecker G. Uterine peristalsis throught the menstrual cycle:
physiological and pathophyiological aspects. Hum Reprod Update 1996; 2: CD-ROM
(video).
- Poindexter AN 3rd, Thompson DJ, Gibbons WE, Findley WE, Dodson MG and Young,
RL. Residual embryos in failed embryo transfer. Fertil Steril 1986; 46: 262-7.
- Ménézo L, Anker D and Salat-Baroux J. Conception and realization of artificial
dried embryo for training in IVF. Acta Europ Fertile 1985; 16: 1.
- Knutzen V, Stratton CJ, Sher G, McNamee PI, Huang TT and Soto-Albors C. Mock
embryo transfer in early luteal phase, the cycle before in vitro fertilization
and embryo transfer: a descriptive study. Fertil Steril 1992; 57: 156-162.
- Mansour RT, Aboulghar MA, Serour GI and Amin YM. Dummy embryo transfer using
methylene blue dye. Hum Reprod 1994; 9: 1257-9.
- Lesny P, Killick SR, Robinson J, Raven G and Maguiness SD. Junctional zone
contractions and embryo transfer: is it safe to use a tenaculum? Hum Reprod
1999; 14: 2367-70.
- Lesny P, Killick SR, Tetlow RL, Robinson J and Maguiness SD. Embryo transfer-can
we learn anything new from the observation of junctional zone contractions?
Hum Reprod 1998; 13: 1540-6.
- Nabi A, Awonuga A, Birch H, Barlow S and Stewart B. Multiple attempts at
embryo transfer: does this affect in-vitro fertilization treatment outcome?
Hum Reprod 1997; 12: 1188-1190.
- Sallam HN, Agameya AF, Rahman AF, Ezzeldin F, Sallam AN. Ultrasound measurement
of the uterocervical angle before embryo transfer: a prospective controlled
study. Hum Reprod 2002;17(7):1767-72.
- Lewin A, Schenker JG, Avrech O, Shapira S, Safran A and Friedler S. The role
of uterine straightening by passive bladder distension before embryo transfer
in IVF cycles. J Assist Reprod Genet 1997; 14: 32-34.
- Dorn C, Reinsberg J, Schlebusch H, Prietl G, Van der Ven H and Krebs D. Serum
oxytocin concentration during embryo transfer procedure. Eur. J Obstet Gynecol
Reprod Biol 1999; 87: 77-80.
- Hearns-Stokes RM, Miller BT, Scott L, Creuss D, Chakraborty PK and Segars
JH. Pregnancy rates after embryo transfer depend on the provide at embryo
transfer. Fertil Steril 2000; 74: 80-86.
- Strickler RC, Christianson C, Crane JP et al. Ultrasound guidance for human
embryo transfer. Fertil Steril 1985; 43: 54-61.
- Leong M, Leung C, Tucker M, Wong C, and Chan H. Ultrasound-assisted embryo
transfer. J In vitro Fertil Embryo Transf 1986; 3: 383-5.
- Kan AK, Abdalla HI,
Gafar AH, Nappi L, Ogunyemi BO, Thomas A and Ola-ojo OO. Embryo transfer:
ultrasound-guided versus clinical touch. Hum Reprod
1999; 14: 1259-61.
- Cohen J. Embryo replacement technology. San Francisco 31 Annual post graduate
course 1998. ASRM.
- Coroleu B, Carreras O, Veiga A, Martell A, Martinez F, Belil I, Hereter
L and Barri PN. Embryo transfer under ultrasound guidance improves pregnancy
rates in in-vitro fertilization. Hum Reprod 2000; 15, 616-20.
- Wood EG, Batzer FR, Go KJ, Gutmann JN and Corson SL. Ultrasound-guided
soft catheter embryo transfers will improve pregnancy rates in in-vitro fertilization.
Hum Reprod 2000; 15: 107-112.
- Al-Shawaf T, Dave R, Harper J, Linehan, D, Riley P and Craft I. Transfer
of embryos into the uterus: how much do technical factors affect pregnancy
rates? J Assist Reprod Genet 1993; 10: 31-36
- Kato O, Takatsuka R and Asch RH. Transvaginal-transmyometrial embryo transfer:
the Towako method: experience of 104 cases. Fertil Steril 1993; 59: 51-3.
- Groutz A, Lessing J, Wolf Y, Azem F, Yovel I and Amit A. Comparison of
transmyometrial and transcervical embryo transfer in patients with previously
failed in vitro fertilization-embryo transfer cycles and/or cervical stenosis.
Fertil Steril 1997; 67: 1073-6.
- Sharif K, Afnan M, Lenton W, Bilalis D, Hunjan M and Khalaf Y. Transmyometrial
embryo transfer following difficult immediate mock transcervical. Fertil
Steril 1996; 65: 1071-4.
- Mansour RT. Minimizing embryo expulsion after ET: a randomized controlled
study. Hum Reprod; In press
Ragaa Mansour, M.D., Ph.D.
Scientific Director
The EgyptianIVF-ETCenter, Maadi|
Cairo, Egypt
Copyright © Middle East Fertility Society
|