Aaron Spitz, MD,
Center for Male Reproductive Medicine,
24301 Paseo de Valencia
Laguna Hills, CA 92653
The
old story about the birds and the bees has a few new
chapters these days. The developments of in-vitro fertility
(IVF) and intracytoplasmic sperm injection (ICSI) have changed
the biological requirements for human reproduction.
No longer are millions of swimming sperm required to
fertilize an egg. Now only a single sperm is required,
and it does not even have to be moving. Using an extremely
fine glass pipette, an embryologist can inject a single
sperm into a woman's egg with resulting fertilization
and embryo formation. The embryo is then transferred
into the woman's uterus where pregnancy ensues.
Various techniques for extracting sperm from a man's
reproductive organs have been perfected. These techniques
initially were performed on men with anatomical blockages
which could not be surgically corrected. Subsequently
it was discovered that men without enough sperm production
to show any sperm at all in their semen analyses may
still be making low levels of sperm in their testicles,
and sperm could be retrieved from the testicles directly
for successful IVF-ICSI pregnancies.
Furthermore,
as the availability and success of IVF has markedly
increased, many men with vasectomies, who would otherwise
be surgically reconstructable, are encouraged to undergo
sperm retrieval instead. Likewise, patients with neurological
disorders or nerve damage who are unable to ejaculate
naturally may also undergo sperm retrieval instead of
the traditional treatment of electrical stimulation
of the ejaculatory nerves to induce an artificial ejaculation
(termed "electroejaculation").
Experience
and research has led to the understanding that the fluids
in the ejaculate from the prostate and seminal vesicles
are essential for fertilization to occur inside the
woman. Therefore, only ejaculated sperm can be used
for artificial insemination. Sperm that is retrieved
can only be used with IVF and intra-cytoplasmic sperm
injection.
Sperm
may be retrieved from the male reproductive organs through
a surgical incision or percutaneously through a needle.
The technique chosen is primarily determined by whether
the man's underlying problem is a blockage to the transport
of sperm or a failure of the testicles to produce sperm
normally.
In
the case of a blockage, there is typically normal ongoing
sperm production with sperm emerging throughout the
testicles and abundant sperm stored within the epididymis.
All techniques will likely reliably retrieve sperm.
However, in the case of poor sperm production, there
is unlikely to be sperm stored in the epididymis. Sperm
must be retrieved directly from the testicle itself.
Since the quantity of sperm is so low in this situation,
a percutaneous approach with a needle is not likely
to find the sperm, therefore surgical retrieval from
the testicle is recommended.
The various sperm retrieval techniques are termed 1)
Microsurgical Epididymal Sperm Aspiration or MESA, 2)
Percutaneous Epididymal Sperm Aspiration or PESA, 3)
Testicular Sperm Extraction or TESE, 4) Testicular Sperm
Aspiration or TESA, 5) Testicular Perc-Biopsy, and 6)
Testicular Microdissection.
Microsurgical
Epididymal Sperm Aspiration (MESA): An incision is made
through the scrotal skin. Using optical magnification,
the tiny epididymal tubules can be incised and sperm
rich fluid aspirated. A large number of motile sperm
is typically retrieved and it can be used immediately
for intracytoplasmic injection into an egg, or can be
frozen in several batches for delayed or subsequent
cycles of IVF-ICSI should they be necessary.
Percutaneous
Epididymal Sperm Aspiration (PESA): A needle is passed
through the scrotal skin and into the epididymis in
order to aspirate sperm. Because the epididymal tubule
is very delicate and convoluted, the yield with a needle
is typically small and usually only sufficient for a
single cycle of IVF-ICSI performed on the same day as
the PESA. Occasionally sperm may not be reliable retrieved
at all.
Testicular
Sperm Extraction (TESE): Through a small scrotal skin
incision, the testicle is explored. Small pieces of
tissue are cut directly out of the testicle and sperm
is extracted from this tissue by the embryologist. In
cases of poor production, multiple excisions may be
required to find an area containing sperm. In this situation,
the sperm must typically be used within 24 hours of
retrieval. In a patient with a blockage, the sperm are
plentiful enough to survive freezing of the tissue for
later use.
Testicular
Sperm Aspiration (TESA): A needle is passed through
the scrotal skin into the testicle. With syringe suction
and numerous excursions of the needle through the testicle
tissue, a very small amount of testicular tissue can
be retrieved. In the case of obstruction, it will usually
be adequate for a cycle of IVF-ICSI that day, but typically
not for freezing and subsequent use. In the case of
poor sperm production, this technique may be performed
through multiple entry points in the testicle in an
effort to localize where sperm production may be occurring
for subsequent open TESE.
Testis
Perc Biopsy: Similar to TESA, this technique uses a
larger gauge biopsy needle and the yield is larger.
Testis Microdissection: This technique is reserved for
patients with very low levels of sperm production where
extensive searching throughout the testicle is required.
An incision is made in the scrotal skin. Under an operating
microscope, the inner contents of the testicle are dissected
until an area of normal sperm production is identified.
The area is excised and the embryologist extracts the
sperm from this tissue. The yield is typically too low
for reliable freezing, so the procedure is performed
within 24 hours of the woman's egg retrieval.
The various procedures are performed on an outpatient
basis. Because of the large yield, MESA may be reliably
performed on the husband ahead of time allowing him
to recuperate and subsequently assist his wife at the
time of her egg retrieval. The procedures may be performed
with various degrees of anesthesia ranging from local
to general. The recovery from the incisional procedures
is similar to that of a vasectomy-48 hours of very limited
activity and about one week of no sex or exercise. The
recovery from a percutaneous procedure is less.
The
risks of the various retrieval procedures are similar,
mainly bleeding, infection, and permanent damage to
the testicle resulting in shrinkage and possibly the
need for lifelong testosterone supplementation. Fortunately,
these complications are uncommon. Procedures such as
MESA and PESA potentially scar the epididymis in such
a way as to make a subsequent vasectomy reversal unable
to be performed on that side.
Sperm
retrieval procedures coupled with IVF-ICSI have enabled
men with surgically intractable obstructions and men
who have severely low sperm production with no sperm
in their ejaculate to father children. Due to the costs
and risks involved to both partners, the consensus statement
of the American Society for Reproductive Medicine indicates
that for a man who has had a vasectomy and whose partner
has no known infertility risk factors, vasectomy reversal
is usually recommended over sperm retrieval with IVF-ICSI.
|
