What Is a SIS Test?
A SIS test is a saline infusion sonography exam, also called a sonohysterogram or saline sonogram. It is a type of pelvic ultrasound in which sterile saline is placed into the uterus through a thin catheter so the lining of the uterus can be seen more clearly. The test is commonly used during fertility workups, evaluation of abnormal bleeding, and before certain reproductive treatments.
In plain English, the SIS test helps a clinician look inside the uterus for problems such as polyps, fibroids, scar tissue, adhesions, or structural abnormalities that might affect fertility, implantation, miscarriage risk, or menstrual symptoms.
Although SWMR focuses on men’s health and fertility, this is a term many men and partners encounter while researching couples fertility testing. If you are trying to conceive, an SIS test may be part of your partner’s evaluation when pregnancy is not happening as expected or before treatments like IUI or IVF.
Table of Contents
- What Is a SIS Test?
- Key Takeaways
- Why Is a SIS Test Done?
- How the Test Works
- When in the Menstrual Cycle It Is Scheduled
- What a SIS Test Can Show
- Normal vs Abnormal Results
- SIS Test vs HSG vs Transvaginal Ultrasound vs Hysteroscopy
- What It Means for Fertility
- How to Prepare
- What to Expect During and After
- Risks, Side Effects, and Safety
- When to Call a Doctor
- Questions to Ask Your Doctor
- Related Tests and Terms
- Frequently Asked Questions
- References
Key Takeaways
- A SIS test is a saline infusion ultrasound of the uterus used to detect problems inside the uterine cavity.
- It is commonly ordered for infertility, recurrent miscarriage, abnormal uterine bleeding, or suspected polyps or fibroids.
- The test usually takes about 15 to 30 minutes and is often done in the office.
- Most people have mild cramping, but severe pain is uncommon.
- A normal SIS suggests the uterine cavity looks smooth and open without obvious filling defects.
- Abnormal results may show polyps, submucosal fibroids, scar tissue, a uterine septum, or retained tissue.
- For fertility, the SIS test can identify uterine issues that may interfere with implantation or pregnancy maintenance.
- It is different from an HSG, which focuses more on the fallopian tubes, though some versions of saline ultrasound may also assess tubal patency.
Why Is a SIS Test Done?
A SIS test is ordered when a clinician needs a better view of the inside of the uterus than a standard ultrasound can provide. On a routine transvaginal ultrasound, the uterine walls may lie against each other, making small lesions hard to see. Saline gently separates those walls, creating contrast so subtle abnormalities stand out more clearly.
Common reasons for a SIS test include:
- Infertility evaluation
- Recurrent pregnancy loss
- Abnormal uterine bleeding, including heavy periods or bleeding between periods
- Suspected uterine polyps or fibroids
- Evaluation before IVF or embryo transfer
- Assessment for uterine scar tissue after surgery, infection, or miscarriage management
- Follow-up of an abnormal pelvic ultrasound
- Investigation of congenital uterine anomalies, such as a septate uterus
How the SIS Test Works
The basic idea is simple: a small amount of sterile saline is instilled into the uterine cavity while transvaginal ultrasound images are taken.
Step-by-step
- You lie on an exam table, similar to a pelvic exam or transvaginal ultrasound.
- A speculum is placed into the vagina so the cervix can be seen.
- The cervix may be cleaned with an antiseptic solution.
- A thin catheter is passed through the cervical opening into the uterus.
- The speculum is removed.
- A transvaginal ultrasound probe is inserted.
- Sterile saline is slowly infused through the catheter.
- As the uterus fills, the clinician watches the ultrasound images for abnormalities.
Some clinics combine saline with air bubbles or contrast to better evaluate whether the fallopian tubes are open. Depending on the method used, this may be called a contrast sonography study or HyCoSy, rather than a standard SIS.
When in the Menstrual Cycle Is a SIS Test Scheduled?
The SIS test is usually done after the menstrual period ends but before ovulation, often in the early to mid-follicular phase of the cycle. This timing matters for a few reasons:
- The uterine lining is typically thinner and easier to evaluate.
- It reduces the chance of performing the test during an early pregnancy.
- There is often less bleeding, which improves image quality.
If someone has irregular cycles, the clinic may use the timing of recent bleeding, ovulation tracking, or a pregnancy test to schedule the procedure safely.
What Can a SIS Test Show?
The main strength of a SIS test is visualizing the endometrial cavity or inner contour of the uterus. It is especially useful for identifying a “filling defect,” meaning something protrudes into or distorts the cavity.
Conditions a SIS test may detect
- Endometrial polyps — small growths arising from the uterine lining
- Submucosal fibroids — fibroids that bulrow into the uterine cavity
- Intrauterine adhesions or scar tissue, sometimes associated with Asherman syndrome
- Septate uterus or other congenital uterine anomalies
- Thickened or irregular endometrium
- Retained products of conception in selected clinical settings
- Focal lesions not clearly visible on routine ultrasound
What a SIS test does not do as well
- It is not the main test for semen quality, sperm count, testosterone, or male fertility factors.
- It does not directly diagnose endometriosis outside the uterus.
- It may not fully evaluate the outer shape of the uterus or pelvic organs the way MRI or laparoscopy sometimes can.
- It is not always the best standalone test for fallopian tube patency unless a modified contrast technique is used.
Normal vs Abnormal SIS Test Results
If you are reading a fertility report or trying to understand what a doctor means by a “normal saline sonogram,” this section is usually what matters most.
What a normal SIS test usually means
A normal SIS generally means the uterine cavity appears smooth, symmetric, and free of obvious lesions. There is no clear sign of a polyp, fibroid projecting into the cavity, adhesions, or structural distortion.
What an abnormal SIS test may mean
An abnormal result means something about the cavity looks irregular, occupied, blocked, or anatomically unusual. The exact significance depends on the finding, its size, its location, symptoms, and whether fertility is a concern.
| Finding | What It Means | Possible Fertility Impact | Typical Next Step |
|---|---|---|---|
| Normal cavity | No obvious intracavitary abnormality | Uterine cavity likely not the main issue | Continue broader fertility workup if needed |
| Endometrial polyp | Localized growth from the uterine lining | May impair implantation or cause bleeding in some cases | Discuss hysteroscopic removal if clinically indicated |
| Submucosal fibroid | Fibroid distorting the cavity | Can interfere with implantation or pregnancy outcomes | Consider hysteroscopic or surgical evaluation |
| Adhesions/scar tissue | Bands of tissue partially sticking cavity walls together | May reduce implantation space and affect menstruation | Often confirmed and treated with hysteroscopy |
| Septum or uterine anomaly | Congenital difference in uterine shape or cavity partition | May be linked with miscarriage or adverse pregnancy outcomes | Further imaging or specialist evaluation |
| Irregular/thickened lining | Nonuniform endometrial appearance | Context-dependent; depends on age, cycle timing, symptoms | May require biopsy or additional testing |
SIS Test vs Other Common Fertility and Gynecology Tests
People often confuse the SIS exam with an HSG, regular pelvic ultrasound, or hysteroscopy. They overlap, but they are not the same.
| Test | Best For | How It Works | What It Shows Best | Limitations |
|---|---|---|---|---|
| SIS test / saline infusion sonography | Inside of the uterine cavity | Saline + transvaginal ultrasound | Polyps, submucosal fibroids, adhesions, cavity shape | Does not always fully assess tubes unless modified contrast is used |
| Transvaginal ultrasound | General pelvic anatomy | Ultrasound probe in the vagina | Ovaries, uterus size, fibroids, lining thickness | Can miss small intracavitary lesions |
| HSG (hysterosalpingogram) | Fallopian tube patency | X-ray + contrast dye through cervix | Blocked tubes, cavity outline | Uses radiation; less detailed than SIS for some cavity lesions |
| Hysteroscopy | Direct visualization and treatment | Small camera inserted through cervix | Confirms and can treat many uterine cavity abnormalities | More invasive than SIS |
| MRI | Complex anatomy | Magnetic imaging | Detailed anatomy, selected fibroids, congenital anomalies | Usually not first-line for routine infertility workup |
SIS test vs HSG: which is better?
Neither is universally “better.” They answer different questions.
- If the main concern is the shape and health of the uterine cavity, an SIS test is often preferred.
- If the main concern is whether the fallopian tubes are open, an HSG is commonly used.
- Some fertility practices use both, especially when a couple is trying to identify all possible barriers to conception.
What Does a SIS Test Mean for Fertility?
For fertility, the SIS test matters because implantation and early pregnancy depend not just on sperm and egg quality, but also on a healthy uterine environment. Even if ovulation is regular and semen analysis is acceptable, a uterine cavity problem can still reduce the chances of successful conception or ongoing pregnancy.
How uterine cavity abnormalities can affect fertility
- Polyps may interfere with implantation in some patients.
- Submucosal fibroids can distort the cavity and are more likely to affect fertility than fibroids located entirely within the uterine wall or outside the uterus.
- Scar tissue can reduce the normal surface area of the endometrium.
- Septa and structural anomalies may increase miscarriage risk or complicate implantation.
Not every abnormality causes infertility, and not every lesion needs treatment. Small findings can be incidental. The decision to intervene depends on clinical context, symptoms, age, prior pregnancy history, embryo transfer plans, and the suspected degree of cavity distortion.
Why men and partners should understand this test
Fertility is a couple-level issue. If you are a man researching a partner’s workup, the SIS test is one piece of a broader picture that may also include:
- Semen analysis
- Sperm morphology, motility, and concentration
- Hormone testing
- Ovulation assessment
- Ovarian reserve testing
- Tubal patency testing
- Evaluation of the uterine cavity
Understanding what the SIS does can help you follow the workup, ask better questions, and make more informed decisions as a couple.
How to Prepare for a SIS Test
Preparation instructions vary by clinic, but common recommendations include the following.
Before the appointment
- Schedule the test after the period but before ovulation.
- Tell the clinic if there is any chance of pregnancy.
- Report symptoms of infection such as fever, unusual discharge, pelvic pain, or a known STI exposure.
- Ask whether you should take an over-the-counter pain reliever beforehand if you are allowed to use one.
- Bring pads or a liner, since some saline may leak out after the procedure.
Who may need to postpone
- Someone with a possible current pregnancy
- Someone with active pelvic infection or cervicitis
- Someone having heavy bleeding that would limit image quality
What to Expect During and After the Procedure
During the SIS test
Most people describe the sensation as pressure, cramping, or a feeling similar to menstrual cramps. Some feel almost nothing. Others feel stronger cramping for a few minutes when the catheter is placed or when the saline distends the uterus.
After the SIS test
Common short-term effects include:
- Mild cramping
- Light spotting
- Watery fluid leakage from the vagina as saline drains out
These symptoms usually resolve quickly. Many people return to normal activities the same day unless their clinician recommends otherwise.
How long does a SIS test take?
The procedure itself often takes around 10 to 20 minutes, though the full appointment may be a bit longer.
Risks, Side Effects, and Safety
The SIS test is generally considered safe, especially when performed in an appropriate clinical setting. That said, no procedure is entirely risk-free.
Possible risks
- Cramping or discomfort
- Spotting
- Infection, which is uncommon but important to watch for
- Vasovagal symptoms, such as dizziness or lightheadedness in some people
- Technical difficulty if the cervix is hard to pass or the uterus is in a position that makes catheter placement more challenging
What’s normal after a SIS test vs what’s not?
| After the Test | Usually Normal | May Need Medical Attention |
|---|---|---|
| Cramping | Mild and short-lived | Severe or worsening pain |
| Bleeding | Light spotting | Heavy bleeding |
| Discharge | Watery saline leakage | Foul-smelling discharge |
| General symptoms | Brief lightheadedness in some cases | Fever, chills, significant weakness |
When to Call a Doctor After a SIS Test
Seek medical advice promptly if there is:
- Fever
- Increasing pelvic pain
- Heavy bleeding
- Foul-smelling vaginal discharge
- Symptoms that feel substantially worse rather than better over time
These may suggest infection or another complication and should not be ignored.
How Doctors Interpret SIS Findings
The usefulness of a SIS test depends not just on what the scan shows, but on how the result fits into the larger clinical picture.
Factors that influence interpretation
- Age and reproductive goals
- Symptoms, such as bleeding, pain, or infertility
- Cycle timing, since endometrial appearance changes through the month
- Pregnancy history, including miscarriage or implantation failure
- Prior surgeries, such as D&C, cesarean delivery, myomectomy, or hysteroscopic procedures
- Other fertility test results, including semen analysis and ovulatory status
Why a report may not give a final diagnosis by itself
A SIS often identifies an abnormality but does not always definitively classify it. For example, a filling defect may be highly suggestive of a polyp, yet some patients still need hysteroscopy or pathology for confirmation. Likewise, a uterine shape abnormality may require MRI, 3D ultrasound, or specialist review to distinguish one congenital anomaly from another.
What Happens If the SIS Test Is Abnormal?
Next steps depend on the problem found. A SIS is a diagnostic tool, not usually the treatment itself.
Common follow-up options
- Observation if the finding is small, incidental, and unlikely to affect symptoms or fertility.
- Hysteroscopy for direct visualization and possible removal of polyps, scar tissue, or submucosal fibroids.
- Additional imaging such as 3D ultrasound or MRI if anatomy is unclear.
- Endometrial biopsy in selected cases of abnormal bleeding or lining concerns.
- Timing reproductive treatment around correction of the uterine issue, especially before embryo transfer.
Examples of possible treatment paths
- Endometrial polyp: hysteroscopic polypectomy may be recommended, particularly in infertility or abnormal bleeding.
- Submucosal fibroid: hysteroscopic myomectomy may be considered if it distorts the cavity.
- Adhesions: hysteroscopic adhesion removal may be used.
- Septum: some patients are considered for hysteroscopic septum resection after specialist evaluation.
Treatment should be individualized. Not every abnormality requires surgery, and not every fertility patient benefits from intervention.
Common Myths and Misconceptions About the SIS Test
Myth: A normal SIS means fertility is normal
Reality: A normal uterine cavity is reassuring, but fertility depends on many factors, including ovulation, egg quantity and quality, sperm health, tubal status, age, and timing.
Myth: An abnormal SIS means pregnancy is impossible
Reality: Many uterine findings are treatable, and some do not meaningfully reduce the chance of pregnancy. The impact depends on the exact abnormality.
Myth: SIS and HSG are the same test
Reality: They are different. SIS is best known for evaluating the uterine cavity, while HSG is more classically used to assess the fallopian tubes.
Myth: The procedure is always extremely painful
Reality: Experiences vary. Many patients have only mild, brief cramping.
Myth: The SIS test is only relevant to women, so men do not need to understand it
Reality: In fertility care, both partners benefit from understanding the full diagnostic process. Uterine health can be just as important as semen parameters when a couple is trying to conceive.
Questions to Ask Your Doctor About a SIS Test
- Why are you recommending a SIS test in this situation?
- What are you specifically looking for: polyps, fibroids, scar tissue, or something else?
- When should the test be scheduled in the cycle?
- Should any medications be taken beforehand for pain relief?
- Will this test also evaluate whether the fallopian tubes are open?
- If the result is abnormal, what are the likely next steps?
- Could a finding on SIS change the plan for IUI, IVF, or embryo transfer?
- Would hysteroscopy be needed to confirm or treat the finding?
Related Tests and Terms
- Sonohysterogram: another common name for the SIS test
- Saline infusion sonography: the full medical term
- Transvaginal ultrasound: routine pelvic ultrasound through the vagina
- HSG: hysterosalpingogram, an X-ray test often used to check fallopian tubes
- Hysteroscopy: direct camera-based evaluation of the uterine cavity
- Endometrial polyp: a common intracavitary growth seen on SIS
- Submucosal fibroid: a fibroid protruding into the uterine cavity
- Intrauterine adhesions: scar tissue within the uterus
- Uterine septum: a congenital partition in the uterine cavity
Why This Glossary Term Appears in Men’s Health and Fertility Research
If you landed here from a men’s fertility search, you may be wondering why a uterine imaging test shows up in your research. The answer is simple: fertility is often evaluated as a shared system. Even when the original concern is low sperm count, poor sperm motility, abnormal morphology, or delayed conception, the female partner’s uterine cavity may still need evaluation.
In practical terms, couples fertility workups often move in parallel:
- The male partner may have semen analysis, hormone testing, or varicocele assessment.
- The female partner may have ovulation testing, ovarian reserve labs, tubal assessment, and a SIS test.
Understanding each test reduces confusion, helps with decision-making, and makes specialist visits more productive.
Frequently Asked Questions
Is a SIS test painful?
Usually it causes mild to moderate cramping rather than severe pain. Some people feel only pressure, while others experience brief menstrual-like cramps during saline infusion.
How long does a SIS test take?
The imaging portion often takes 10 to 20 minutes. The full appointment may last longer depending on check-in, preparation, and discussion of results.
What is the difference between a SIS test and a sonohysterogram?
They are the same thing. “SIS test,” “saline infusion sonography,” and “sonohysterogram” are commonly used interchangeably.
Can a SIS test detect blocked fallopian tubes?
A standard SIS is mainly used to evaluate the uterine cavity. Some modified ultrasound contrast studies can assess tubal patency, but a traditional HSG is more commonly used for that purpose.
Can you try to conceive in the same cycle as a SIS test?
That depends on your clinician’s advice, cycle timing, and the reason for the test. Some patients may continue trying, but you should follow the specific instructions from your fertility or gynecology team.
Why would a fertility doctor order a SIS test before IVF?
Because even with good embryos, implantation may be affected by a polyp, fibroid, scar tissue, or cavity abnormality. The test helps confirm the uterus is ready for transfer.
What if the SIS test is normal but pregnancy still is not happening?
A normal SIS rules out many uterine cavity problems, but infertility can still stem from sperm factors, ovulatory disorders, age-related egg factors, tubal disease, endometriosis, or unexplained causes.
Does a SIS test use radiation?
No. It uses ultrasound, not X-ray radiation.
Can a SIS test remove a polyp or fibroid?
No. It is primarily a diagnostic test. If a lesion is found, treatment is often done later with hysteroscopy or another procedure if needed.
Is a SIS test safe?
It is generally safe when appropriately performed, though mild cramping and spotting are common and infection is a rare potential complication.
References
- American Society for Reproductive Medicine. Guidance and committee opinions related to infertility evaluation and uterine cavity assessment.
- American College of Obstetricians and Gynecologists. Patient education and clinical guidance on abnormal uterine bleeding, fibroids, and hysteroscopy.
- Society of Radiologists in Ultrasound. Practice resources related to pelvic ultrasound and sonohysterography.
- MedlinePlus, U.S. National Library of Medicine. Educational resources on sonohysterography and reproductive health testing.
- Merck Manual Consumer and Professional resources on infertility evaluation and uterine abnormalities.
- Peer-reviewed reviews in obstetrics, gynecology, and reproductive medicine journals on saline infusion sonography, endometrial polyps, submucosal fibroids, and infertility workup.
