Saline Infusion Sonohysterography (SIS)

Author: Dr Monica Pahuja*

What is saline infusion sonohysterography (SIS)?

Saline infusion sonohysterography (SIS) or saline ultrasound uterine scan is a test where a small volume of saline (salt solution) is inserted into the uterus (or womb). This allows the lining of the uterus (endometrium) to be clearly seen on an ultrasound scan. It is also known as a saline ultrasound uterine scan.

“Ultrasound” is the term used for an imaging test that uses high frequency soundwaves.

SIS helps to see if there is any thickening of the endometrium of the uterus, or if there are polyps. Polyps are small growths of the endometrium. The scan can also be performed in the assessment of post menopausal endometrium or possible Asherman’s Syndrome (a condition caused by the presence of scars in the uterine cavity).

How do I prepare for a SIS?

No special preparation is required. The test is best performed as your period finishes, day 8-9 of your menstrual cycle. So it is best to arrange your appointment according to your period dates.

You will be asked to go to the toilet and empty your bladder prior to the test. If you are using a tampon, it will need to be removed. You can still have the test if the period is just finishing and bleeding is light.

An SIS scan cannot be performed if you are pregnant or if you have a pelvic inflammatory disease (PID). You must advise your referring doctor or staff where you are having the scan if you have either of these conditions.

It is a good idea to wear comfortable clothing that gives easy access to the lower part of your body

What happens during a SIS?

After emptying your bladder you will be asked to undress from the waist down and you may be asked to wear a gown. You will then be asked to lie on an examination couch. A speculum (an instrument used to hold open the vagina so that it can be examined) is inserted into the vagina. A soft catheter (a thin plastic tube) is gently inserted into the vagina and into the uterus through the cervix (the neck of the uterus).

A small amount of saline (salt solution) is inserted through the catheter into the uterine cavity.
After the speculum is removed, the transducer (see transvaginal ultrasound) is inserted into the vagina. The saline fluid within the uterus allows the lining of the uterus to be imaged clearly on the ultrasound screen and show any endometrial abnormality.

The transducer is slightly larger than a tampon and especially shaped to fit comfortably into the vagina. A protective cover is placed over the transducer and lubricating gel is applied to it for ease of insertion. It is gently moved around and pictures or images of the inside of the uterus are obtained.

Are there any after effects of a SIS?

After the test there is a small trickle of fluid from the vagina. This is the saline fluid which was inserted through the catheter coming out. It is commonly slightly blood stained and this may continue for 24 hours after the test. You may wish to use a sanitary pad but you are advised not to use tampons for the rest of the day after the test.

Most patients feel normal after the test with no after effects. Some patients may have some pelvic discomfort (like a mild period pain) but this settles after a few minutes up to perhaps an hour or so and is very uncommon.

Some patients may feel slight dizziness but this passes within a few minutes.
You will generally be well enough to drive home and resume normal activities, such as going back to work.

How long does a SIS take?

The entire procedure usually takes about 30 minutes. Most of this time is occupied by scanning before and after the saline is put into the uterus. The actual time taken for the saline to be put in is only 2-3 minutes.

What are the risks of a SIS?

The test is very safe. The main risk is that of infection within your uterus being introduced by the procedure. This is extremely uncommon and is treated with antibiotics if it occurs.

What are the benefits of a SIS?

Inserting the saline fluid into the uterus allows very clear ultrasound images to be taken of the lining of the uterus and any abnormalities such as thickening of the endometrium or polyps can be easily seen. This will help to guide the discussion between you and your doctor about any further investigation or treatment that may be needed.

Who does the SIS?

The examination is always performed by a specialist doctor, usually an imaging specialist (radiologist) or obstetrician sonologist (an obstetrician qualified in performing ultrasound examinations).

Where is a SIS done?

The examination is performed in a radiology department of a hospital, private radiology practice or at a specialist clinic for obstetric and gynaecological imaging. The examination is performed in the privacy of a ultrasound room which may be dimly lit to allow the images on the ultrasound machine to be clearly seen by the person performing the scan.

When can I expect the results of my SIS?

The time that it takes your doctor to receive a written report on the test or procedure you have had will vary, depending on:

  • the urgency with which the result is needed;
  • the complexity of the examination;
  • whether more information is needed from your doctor before the examination can be interpreted by the radiologist;
  • whether you have had previous X-rays or other medical imaging that needs to be compared with this new test or procedure (this is commonly the case if you have a disease or condition that is being followed to assess your progress);
  • how the report is conveyed from the practice or hospital to your doctor (i.e. phone, email, fax or mail).

Please feel free to ask the private practice, clinic, or hospital where you are having your test or procedure when the written report will be provided to your doctor.

It is important that you discuss the results with the doctor who referred you, either in person or on the telephone, so that they can explain what the results mean for you.

*The author has no conflict of interest with this topic.

Page last modified on 26/7/2017.

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