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Tubal
Patency Tests
What are tubal patency
tests
Tubal patency tests are undertaken
when the doctors suspect that there are blockages or pelvic adhesions in
the fallopian tubes. These tests include procedures like Gas Insufflation,
Hysterosalpingography (H.S.G.), Laparoscopy, etc.
What is the role of
the fallopian tubes in initiating pregnancy
Healthy fallopian tubes are an essential
pre-requisite for conception to occur. If the tubes are completely blocked,
the sperm are unable to reach the egg to fertilize it. If however,
the tubes are damaged and not completely blocked, the sperm may be able
to reach the egg, but the early embryo is more likely to be trapped in
the distorted tube - a dangerous condition known as an ectopic pregnancy.
Thus it is not enough that the sperm have access to the egg. It is also
necessary that the egg must not be prevented from reaching the open end
of the tube. If the ovaries are surrounded by adhesions, there is a major
barrier between egg and sperm.
What are the causes
of tubal obstruction
The primary cause of tubal obstruction
and pelvic adhesions is infection. Infection can be caused by peritonitis
from acute appendicitis, or it may have arisen within the uterus itself
as a complication of a previous termination of pregnancy, miscarriage or
difficult delivery. In addition, there are a number of women who have chosen
sterilization as a means of permanent birth control and change their minds
for a variety of reasons.
Is it common for women
to have a problem with their tubes
About 15% of women attending an infertility
clinic will have a tubal problem. A perusal of the medical history of half
of these women will show no past history of any probable cause for their
damaged tubes. In such cases it is possible that a viral infection, even
one caught in childhood, has been responsible for the damage.
If there are no indications in your
history that the tubes may be blocked, you will in all likelihood be given
the benefit of the doubt initially while other causes of infertility are
investigated. If, however, there is a definite past history indicating
possible tubal obstruction, a test of tubal patency will be carried out
at a relatively early stage.
What are the various
tubal patency tests
1. Gas Insufflation
This is the oldest method of assessing
tubal patency and is often referred to as "blowing the tubes". It is a
simple test to carry out and does not require a general anaesthetic. An
instrument is inserted into the canal of the cervix and carbon dioxide
gas is "blown" into the cavity of the uterus. The machine controlling the
flow of carbon dioxide also records the pressure of the gas as it builds
up in the uterus.
There will be an increase in pressure
of the gas within the uterus if the tubes are blocked. If the tubes are
open, the initial rise in pressure is followed by a sudden reduction as
the gas escapes along the tubes and into the abdominal cavity.
However, the results of this test
can be difficult to interpret and the test can be unreliable. Furthermore,
if the tubes are blocked, the test gives no information about the location
or nature of the obstruction. The inaccuracy of the test has led it to
be largely superseded by the following two procedures.
2. Hysterosalpingography (H.S.G.)
A hysterosalpingogram is an X-ray
of the uterus and fallopian tubes. An instrument is gently passed into
the canal of the cervix and a special radio-opaque dye is carefully injected
into the cavity of the uterus. The test is performed in the X-ray department
and normally does not require any form of general anaesthetic. It can,
however, cause you to experience a moderate amount of discomfort rather
like period pains.
The dye shows up on an X-ray screen
and the doctor is able to see the fluid filling the uterus and then passing
along both tubes to enter the cavity of the abdomen. If the dye fails to
enter the tubes this may indicate an obstruction at the junction between
the uterus and the tubes or simply a temporary spasm of the tubes at this
site. Sometimes the dye can be seen to enter the tubes, which then become
distended owing to an obstruction at their outer ends.
The H.S.G. can pinpoint the site
of any tubal obstruction and can also show the presence of any irregularity
in the shape of the cavity of the uterus. However, this test cannot identify
the existence of pelvic adhesions, which may be enveloping the ovaries
and preventing eggs from having access to the tubes.
3. Laparoscopy
This is a much more complex procedure
than the previous two tests. It is performed under a general anaesthesia
and will require your admission to hospital.
A tiny incision is made at the lower
border of the umbilicus. The abdominal cavity is then distended with carbon
dioxide gas in order to create more space to accurately view the pelvic
organs. A slim telescope called a laparoscope is then inserted into the
abdominal cavity and the uterus, tubes and ovaries are thoroughly inspected.
The presence of adhesions either
around the tubes or tethering the ovaries can be easily detected, and their
significance assessed. Other pelvic problems such as endometriosis and
fibroids will also be revealed. Tubal patency is tested by injecting methylene
blue dye into the uterus through the cervix. If the tubes are healthy,
the dye can be seen passing along them and escaping through the outer openings
of the tubes.
The great advantage of laparoscopy
over H.S.G. is that it allows the surgeon to have a direct view of the
pelvic organs and thereby permits a much more accurate assessment of tubal
patency and any tubal or ovarian problems. The need for further surgery
can be determined without having to resort to major abdominal surgery at
that time. The majority of patients are able to leave hospital the
following day. The
tiny operation scar is eventually
virtually invisible.
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