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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.
 Normal HSG findings ( the dye appears black and outlines a normal cavity and fallopian tubes)
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.
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. Please ask your doctor to prescribe a pain-killer for you to help you cope better with this. Taking a pain-killer one hour prior to the procedure and then one hour later will help to reduce the pain. One simple way of reducing the pain is to ask the doctor to use a specially designed balloon catheter to do the HSG. Many companies make special disposable catheters for this purpose. These are expensive - but well worth it !
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.
HSG versus Laparoscopy Many doctors advise patients to do a laparoscopy in order to assess their tubal status. We do not think this is a good idea. An HSG can confirm the fallopian tubes are open at a fraction of the cost of a laparoscopy. Why allow the doctor to do a surgical intervention when a simple X-ray can provide all the information we need to treat you intelligently !
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). | 
