In this article:
What is HSG (Hysterosalpingography)?
HSG is an X-ray test that helps check if your fallopian tubes are open and if your uterus has any shape problems. During this test, a special dye is inserted into your uterus through your cervix. As the dye moves through your uterus and fallopian tubes, X-ray images are taken.If the dye flows freely through your tubes, it means they’re likely open. But if it gets blocked or doesn’t pass through, it could mean there’s a blockage preventing pregnancy.
What is SIS (Saline Infusion Sonography)?
SIS is an ultrasound-based test that focuses more on the uterine cavity. In this procedure, sterile salt water (saline) is gently pushed into your uterus through a thin tube. This makes it easier to see the lining and shape of your uterus on an ultrasound.SIS is especially helpful in spotting issues like polyps, fibroids, or scar tissue inside your uterus that could affect your chances of getting pregnant or carrying a pregnancy.
Key Differences Between HSG and SIS
Let’s look at the main ways these two tests are different:| Feature | HSG (Hysterosalpingography) | SIS (Saline Infusion Sonography) |
| Type of Imaging | X-ray | Ultrasound |
| What It Checks | Fallopian tubes & uterus shape | Uterine lining and structure |
| Use of Dye or Fluid | Iodine-based dye | Saline (salt water) |
| Checks Tube Blockage? | Yes | No (not reliably) |
| Radiation Involved? | Yes | No |
| Pain Level | Mild to moderate | Mild |
| Done When? | Usually after your period (Day 6-11) | Also after your period (Day 6-11) |
Why You Might Need an HSG
If your doctor wants to check why you’re not getting pregnant, HSG can help see if your fallopian tubes are blocked or damaged. Blocked tubes can stop the egg and sperm from meeting, so this test gives important answers.HSG is also useful if you’ve had:
- Pelvic infections
- Tubal surgeries
- Ectopic pregnancy in the past
Why You Might Need an SIS
On the other hand, if your doctor suspects there may be growths or abnormalities inside your uterus, they may suggest an SIS. This test helps find:- Polyps
- Fibroids
- Adhesions (scar tissue)
- A uterine septum (a wall inside the uterus)
Can You Have Both Tests?
Yes, and sometimes it’s even recommended. HSG looks at the tubes, while SIS focuses more on the uterus. Together, they give a complete picture of your reproductive organs.Your doctor may suggest both tests if you’ve been trying to conceive for over a year or if you’ve had repeated miscarriages.
What to Expect During the Tests
During an HSG:
- You’ll lie on an X-ray table.
- A thin tube is inserted into your cervix.
- Dye is slowly injected while X-ray images are taken.
- You may feel cramping or discomfort, like period pain.
- The test usually takes about 15–30 minutes.
During an SIS:
- You’ll lie down like during a regular ultrasound.
- A small tube is placed into your uterus.
- Saline is passed through while the doctor uses an ultrasound to check your uterus.
- You may feel a mild fullness or cramping.
- This also takes about 15–30 minutes.
Is There Any Preparation Needed?
For both HSG and SIS, you’ll be asked to come after your period ends but before ovulation starts (usually Day 6 to Day 11 of your cycle). This reduces the chance that you're pregnant during the test and gives a clearer view of your uterus.Also, your doctor might recommend taking a mild painkiller before the test to ease any discomfort.
Are There Any Side Effects or Risks?
Both tests are generally safe, but there are some mild risks.HSG Risks:
- Light spotting
- Cramping
- Rare risk of infection or allergic reaction to the dye
- Mild spotting
- Cramping
- Rare chance of infection
How Soon Can You Try to Conceive After These Tests?
You can usually resume trying in the same cycle unless your doctor advises otherwise. In fact, some people find that their chances of pregnancy increase in the cycle or two after an HSG, especially if minor blockages were cleared during the procedure.Which Test is Better for You?
It depends on what your doctor is looking for.- If you need to check if your tubes are open, HSG is better.
- If the concern is about your uterus’s shape or lining, SIS will give more detailed information.
- In many cases, doing both tests offers the best insight, especially in cases of unexplained infertility.
FAQs on What’s The Difference Between HSG and SIS
- Can HSG or SIS increase the chances of getting pregnant?
In some cases, yes. Especially after an HSG, some women get pregnant more easily, as the dye might clear minor blockages in the tubes. - Is one test more painful than the other?
Most people find both tests bearable. HSG may cause more cramping than SIS, but the pain is usually short-lived. Taking a mild painkiller before the procedure can help. - Will I need both HSG and SIS for a fertility check-up?
Not always, but if your doctor needs a complete view of your uterus and tubes, they may recommend both. It helps give a clearer diagnosis and guide your next steps in treatment.
