| |
|
Headlines:
|
 |
Back to table of contents
Submitted by Dr. Hesham Al-Inany, M.D. Lecturer, Gynaecology
& Obstetrics dept. Kasr El-Aini hospital, Cairo University, Egypt.
|
|
|
During Gamete Micromanipulation sperms are injected into an ovum to assist in
union of the gametes.
|
|
| |
|
|
| |
| |
| |
|
|
| |
|
|
|
Indications
The severely oligospermic patients usually has a combination of multiple
spermatozoal defect (WHO, 1987) with poor chances of spontaneous conception.
In vitro fertilization (IVF) has not contributed to significant improvement
for patients with severe oligospermia (Yovich and Stanger, 1987). Fertilization
rates decreases when inseminating concentrations are reduced .
While tubal embryo transfer (Diamond et al, 1986) improves the pregnancy
rate following fertilization, the fertilization process still requires
the initial semen sample to be more than 5 million/ml (Hamori et al,
1988).
-
Severe multiple sperm factors
Severe forms of oligoasthenoteratozoospermia have very poor prognosis
in terms of treatment and realization of pregnancy. There is significant
reduction in fertilization in triple sperm defects (35.1%, 61 men in
116 cycles), when compared to single sperm defects (61.3% , 121 men
in 206 cycles). Such a combination is to be expected when there is seminiferous
tubular failure, usually of an idiopathic nature.
Tubal embryo transfer (TET) otherwise known as pronuclear stage transfer
(PROST) and tubal embryo stage transfer (TEST) (Yovich et al, 1988)
, does not offer increased hope for patients with severe sperm problems
as the spouses' oocytes still need to be fertilized before transfer
into the fallopian tubes. Such patients have previously relied on artificial
insemination with donor sperm. Now, micro-insemination offers some hope
(Ng et al,1991).
Motility has an important influence on fertilization rates (Bongso
et al, 1989). Immotile spermatozoa may be caused by enviromental or
congenital factors e.g ciliary dyskinesis. Enviromental problems, e.g
drug therapy, usually result in decreased motility, and this can be
improved by removal of the drug or introduction of additives into the
sperm washing procedures (Bongso et al, 1989).
Congenital problems are more difficult to treat and there is the ethical
issue of whether propagation of such genes is desirable or not.
-
Inability to penetrate egg vestments
Chia et al (1984), reported unexplained failed fertilization inspite
of oocytes being mature and spermatozoa of good motility.
The zona-penetration test (Overstreet, 1983) may shed more light on
this defect. The hemi-zona assay will help in the understanding of sperm
penetration through the zona (Burkman et al, 1988).
Spontaneous hardening of the ZP has been described in mouse oocytes
cultured in vitro after increasing resistance to solubilization by chemotrypsin.
Alterations of the surface structure of the zona have been linked to
sperm-binding capacity of the zona . Previous failed attempt of IVF
in such condition is necessary proceeding to gamete micromanipulation
(Ng. et al, 1990).
Specific sperm abnormalities that do not allow attachment of sperm to
oocyte, e.g acrosomeless sperm might also justify sperm injection directly
without IVF trials. (Lalonde et al, 1988).
|
|
|
|
Are you a doctor or a nurse?
Do you want to join the Doctors Lounge online medical community?
Participate in editorial activities (publish, peer review, edit) and
give a helping hand to the largest online community of patients.
Click on the link below to see the requirements:
Doctors Lounge Membership
Application |
|
Limitations
There are limitations to the widespread application of micro-insemination.
It requires expensive equipment and training, time consuming, and currently
yields low fertilization rates. It is still a research procedure and optimal
conditions for its successful application are still not determined (Ng.
et al, 1991)
Contraindications
The absolute contraindication is a genetic abnormality in the male.
There have been no reported studies on the sperm chromosomes of oligospermic
men . It is unlikely to have an increased abnormality in sperm haploid
chromosomes when the peripheral karyotype is normal (Ng et al, 1990).
Peripheral karyotype of the male is highly recommended in any program
of gamete micromanipulation. The incidence of sperm chromosome aberrations
from proper donors varies between 6.6% and 14.3% (Templade et al, 1988).
|
|
send
to a friend
printer
friendly version
