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Hysterosalpingogram (Uterotubogram) or HSG is a
specialized X-ray of the uterus and tubes. Since the word hysterosalpingogram is quite a mouthful, most doctors refer to it as a HSG. Most infertile women who have done a HSG prefer not to refer to it at all, because it is quite a painful procedure.
As the name ( hystero = uterus; salping= tubes; gram = image) suggests, a HSG is an X-ray study of the uterus and tubes which allows the doctor to confirm that the uterine cavity is normal; and that the fallopian tubes are open.
An HSG is done after the
menstrual flow has just stopped - usually on Day 6 or 7 of the period,
at which time the lining of the uterus is thin. It is done in an X-ray
Clinic. The patient is advised to take an antibiotic and a pain-killer
before the procedure by many doctors. After being positioned on the
X-ray table, the doctor places a special instrument into the cervix,
called a cervical cannula, which is made of metal. Many doctors now
prefer to use a balloon catheter , as this makes the procedure less
painful. A radio-opaque dye (a liquid which is opaque to X-rays) is
then injected into the uterine cavity. This is done slowly under
pressure, and pictures are taken - preferably under an image
intensifier. The passage of the dye into the uterine cavity and then
into the tubes and from there into the abdomen can be seen; and X-ray
pictures taken. These provide a permanent record.
At least 3 films need to be taken to provide a
reliable record - including an early film for the uterine cavity; and a
delayed film to make sure the spill in the abdomen is free.
A normal HSG defines the inside of the reproductive
tract. This appears as a triangle (usually white on a black background)
which represents the uterine cavity; and from here the dye enters the
tubes which appear as two long thin lines, one on either side of the
cavity. When the dye spills into the abdomen from a patent ( open)
tube, this appears as a smudge in the X-rays.
Normal HSG findings ( the dye appears black and outlines a normal cavity and fallopian tubes)
An abnormal HSG may show a problem in the uterine
cavity - and this appears as a gap or filling defect. However, the
commonest problems on HSG appear in the tubes. If the tubes are blocked
at the cornual end (at the uterotubal junction), then no dye enters the
tubes and they cannot be seen at all. If the block is at the fimbrial
end then the tubes fill up; but the dye does not spill out into the
abdominal cavity and the end of the tubes are often swollen up.
Sometimes, like any other medical test, the HSG may
provide erroneous results. For example, the cornu of the uterus may go
into spasm, as a result of which the dye may not enter the tubes at
all. This may be interpreted as a tubal block, whereas in reality the
tubes are open. Also, if a hydrosalpinx is very thin and if the dye is
injected under pressure, the dye may appear to spill into the abdomen
through a tear in the wall of the hydrosalpinx - suggesting tubal
patency when really the tubes are closed.
While the HSG is usually very reliable for
determining whether or not the tubes are open, it provides little
information on structures outside the tube which could nevertheless
impair tubal function - such as peritubal adhesions. If the spill is
"loculated",(i.e. it collects in small puddles), the presence of
adhesions can be suspected, but not confirmed.
An HSG can be painful - and when the dye is
injected into the uterine cavity, most women will experience a
considerable amount of pain. You should be prepared for this - and
taking a pain-killer prior to the procedure will help to reduce the
pain.
An HSG can be technically difficult for some women
(especially if the cervix is too small or too tight) - and it is better
if a gynecologist is present at the time of the HSG to assist the
radiologist if needed. Many gynecologists will do the HSG themselves.
The major risk of an HSG is that of spreading an
unrecognized infection from the cervix up into the tubes. This is
uncommon, but in order to reduce the risk, many doctors advise
antibiotic coverage during the procedure.
If the HSG shows that the tubes are closed, then it
may be advisable to repeat the HSG; and also to do a laparoscopy to
confirm this diagnosis.
Laparoscopy. This has already been described, and is the gold standard for making a diagnosis of tubal disease.
The
trouble with both HSG and laparoscopy is that they only provide
information as to whether or not the tube is open or closed. While a
closed tube will never work, they do not provide any information on how
well an apparently open tube works. Remember, that just because a tube
is patent does not necessarily mean that it works!
Laparoscopy shows a large hydrosalpinx on the right side
Another limitation is that they will rarely provide
any information as to why the tubes are blocked. Occasionally, however,
this can be suspected by other signs (for example, by seeing the
tubercles diagnostic of TB in the abdomen during laparoscopy). | 
