During fertility evaluation, a routine pelvic ultrasound can provide useful information about the ovaries, uterus and endometrial lining. Sometimes, however, doctors need a clearer view of the inside of the uterine cavity. This is where saline sonography for fertility may be recommended.
Saline sonography, also called saline infusion sonography (SIS) or sonohysterography, is an ultrasound procedure in which a small amount of sterile saline is placed inside the uterus. The fluid gently separates the walls of the uterine cavity, allowing abnormalities such as polyps, submucosal fibroids or adhesions to be seen more clearly than on routine ultrasound alone.
The test is mainly diagnostic. It helps fertility specialists understand whether something inside the uterus may need further assessment before trying naturally, undergoing IUI, or planning embryo transfer.
What Is Saline Sonography?
Saline infusion sonography is a specialised ultrasound examination of the uterine cavity.
During the procedure, a thin catheter is passed through the cervix. Sterile saline is then slowly introduced into the uterus while a transvaginal ultrasound is performed.
Normally, the front and back walls of the uterus lie close together. When saline enters the cavity, it creates temporary separation between these surfaces. This makes the outline of the cavity much easier to evaluate.
According to ASRM, sonohysterography provides a clearer assessment of the size and shape of the uterine cavity and is useful for detecting abnormalities such as endometrial polyps, submucous fibroids and intrauterine adhesions.
Why Is an SIS Fertility Test Recommended?
An SIS fertility test may be advised when a doctor wants to examine the uterine cavity more closely.
Possible reasons include:
- Difficulty conceiving
- Abnormal findings on routine ultrasound
- Suspected endometrial polyp
- Suspected submucosal fibroid
- Possible uterine adhesions
- Irregular or abnormal bleeding
- Recurrent pregnancy loss in selected cases
- Evaluation before certain fertility treatments
- Further assessment after an unclear HSG or ultrasound finding
Not every fertility patient needs saline sonography. The test is usually recommended when the findings could change treatment planning.
What Can Saline Sonography Detect?
One of the main strengths of sonohysterography is its ability to outline abnormalities that project into or distort the uterine cavity.
Endometrial Polyps
Polyps are overgrowths of tissue arising from the uterine lining.
They may be associated with:
- Spotting between periods
- Heavy or irregular bleeding
- No symptoms at all
Saline around the polyp can make its shape and location easier to see on ultrasound.
Submucosal Fibroids
Fibroids are non-cancerous growths of uterine muscle. A submucosal fibroid grows toward or into the uterine cavity.
Because location matters, SIS can help determine how much of a fibroid is affecting the cavity.
Intrauterine Adhesions
Adhesions are bands of scar tissue within the uterus. They may occur after certain uterine procedures, infections or pregnancy-related interventions.
SIS may help identify areas where the normal shape of the cavity appears altered.
Uterine Shape or Cavity Abnormalities
The test may also reveal an irregular uterine cavity that requires further assessment.
ASRM notes that sonohysterography has high positive and negative predictive values for detecting intrauterine abnormalities such as polyps, submucous fibroids and adhesions.
How Is Saline Sonography Different From a Normal Ultrasound?
A routine transvaginal ultrasound is useful for evaluating:
- Ovaries
- Fibroids within the uterine muscle
- Ovarian cysts
- Endometrial thickness
- Pelvic anatomy
However, small abnormalities inside the uterine cavity may sometimes be difficult to define when the cavity walls are touching.
During an SIS, saline creates contrast between the cavity and surrounding tissue. This makes the inner contour of the uterus easier to examine.
So, a normal pelvic ultrasound and a uterine cavity test with saline do not provide exactly the same information.
What Happens During the SIS Procedure?
The procedure is usually performed in an outpatient clinic and generally takes a short time.
Step 1: Initial Ultrasound
A routine transvaginal ultrasound may first be performed to examine the uterus and ovaries.
Step 2: Cervical Access
A speculum is placed in the vagina so the doctor can see the cervix.
Step 3: Catheter Placement
A thin catheter is gently passed through the cervix into the uterus.
Step 4: Saline Infusion
Sterile saline is slowly introduced.
Step 5: Ultrasound Imaging
The ultrasound probe is used while saline fills the cavity. The doctor examines the uterine walls, endometrium and any abnormal structures.
ACOG describes sonohysterography as an ultrasound procedure where fluid introduced through a thin tube helps show more detail than ultrasound alone.
When During the Menstrual Cycle Is SIS Usually Done?
Timing depends on the reason for the test and the doctor’s protocol.
For women who menstruate regularly, saline sonography is commonly planned after menstrual bleeding has finished and before ovulation, when the uterine lining is relatively thin and pregnancy is unlikely.
The medical team will give you the exact appointment date based on your menstrual cycle.
Tell your doctor if:
- Your period is delayed
- Pregnancy may be possible
- You have symptoms of pelvic infection
- You have unusual vaginal discharge or fever
Is Saline Sonography Painful?
Most patients can complete the test without anaesthesia.
Possible sensations include:
- Pressure when the catheter is placed
- Period-like cramps when saline enters the uterus
- Mild discomfort during transvaginal ultrasound
The experience varies from person to person.
Some patients feel only mild pressure, while others may experience stronger temporary cramping.
If you are worried about discomfort, ask your doctor whether any pain-relief medicine should be taken beforehand rather than taking medication on your own.
What Happens After Saline Sonography?
Most people can return to their usual activities shortly after the procedure.
Temporary effects may include:
- Mild cramping
- Watery discharge as saline leaves the uterus
- Light spotting
Contact your doctor if you develop concerning symptoms such as:
- Fever
- Severe or worsening pelvic pain
- Heavy bleeding
- Foul-smelling discharge
These symptoms are not expected as part of routine recovery and should be medically assessed.
Saline Sonography vs Hysteroscopy
SIS and hysteroscopy can both evaluate the uterine cavity, but they are different procedures.
Feature | Saline Sonography | Hysteroscopy |
Main technique | Ultrasound + saline | Camera placed inside uterus |
Direct view of cavity | No | Yes |
Diagnostic use | Yes | Yes |
Can treat abnormality during procedure | No | Often possible |
Polyp/fibroid assessment | Can identify or suggest | Can directly inspect and treat selected lesions |
Invasiveness | Less invasive | More invasive |
Anaesthesia | Usually not required | Depends on diagnostic vs operative procedure |
Hysteroscopy is considered a definitive method for diagnosing and treating many intrauterine abnormalities.
Ova Fertility & Women Care similarly explains that hysteroscopy allows the doctor to directly view the inside of the uterus and, when required, remove polyps, treat adhesions, resect selected submucosal fibroids or correct other cavity abnormalities.
If SIS identifies a finding that may require direct evaluation or treatment, your fertility specialist may discuss hysteroscopic evaluation and treatment as the next step.
Does an Abnormal SIS Result Always Mean Surgery?
No.
Finding something during saline sonography does not automatically mean hysteroscopic surgery is required.
Treatment depends on:
- Type of abnormality
- Size
- Location
- Symptoms
- Fertility history
- Whether the finding significantly affects the uterine cavity
For example, Ova Fertility & Women Care notes that some uterine cavity findings are small and may not require surgery, while others may justify correction depending on symptoms and reproductive goals.
The fertility specialist should interpret the scan in the context of the patient’s overall fertility situation.
Can Saline Sonography Check Fallopian Tubes?
Basic saline sonography is primarily used to evaluate the uterine cavity.
The appearance of fluid outside the uterus may sometimes suggest that at least one fallopian tube is open, but standard saline sonography cannot reliably establish which individual tube is patent.
When detailed tubal assessment is required, doctors may recommend a dedicated test such as:
- HSG
- HyCoSy
ASRM specifically notes that simple saline sonography may indicate that tubal flow exists but cannot reliably distinguish unilateral from bilateral patency.
When Should You Consult a Fertility Specialist?
A uterine cavity assessment may be considered if you have:
- Difficulty conceiving
- Repeated abnormal bleeding
- Suspected uterine polyps
- Fibroids close to the uterine cavity
- Previous uterine surgery
- Concerns about adhesions
- Repeated pregnancy loss
- An abnormal fertility ultrasound
Your doctor can decide whether routine ultrasound, saline sonography, hysteroscopy or another investigation is the most appropriate next step.
Final Thoughts
Saline sonography for fertility gives doctors a clearer view of the uterine cavity when routine ultrasound does not provide enough detail. By introducing sterile saline during ultrasound, the test can help identify polyps, fibroids, adhesions and other changes that may need further evaluation.
An abnormal result does not automatically mean surgery is required. The next step depends on what was found and whether it is likely to affect symptoms, conception or fertility treatment.
If you are undergoing fertility evaluation and your doctor suspects a uterine cavity problem, the team at Ova Fertility & Women Care can assess whether an SIS, hysteroscopy or another investigation is appropriate for your individual situation.
FAQ
1. What is saline sonography for fertility?
Saline sonography for fertility is an ultrasound procedure in which sterile saline is introduced into the uterus to provide a clearer view of the uterine cavity. It can help identify polyps, submucosal fibroids, adhesions and other cavity abnormalities.
2. Is an SIS fertility test painful?
An SIS fertility test may cause temporary period-like cramps or pressure, particularly while saline is being introduced. Many patients experience only mild discomfort, although individual pain levels vary.
3. How is sonohysterography different from a normal ultrasound?
A normal ultrasound examines the uterus without placing fluid inside the cavity. During sonohysterography, saline gently separates the uterine walls, making abnormalities inside the cavity easier to identify.
4. Can saline sonography detect blocked fallopian tubes?
Basic saline sonography is mainly a uterine cavity test and does not reliably show whether each individual fallopian tube is open. A dedicated tubal test such as HSG or HyCoSy may be recommended when detailed tubal assessment is required.
5. What happens if saline sonography finds a polyp or fibroid?
Your doctor will consider the size, location, symptoms and fertility relevance of the finding. If direct confirmation or treatment is required, hysteroscopy may be discussed because it allows the uterine cavity to be viewed directly and selected abnormalities to be treated.
Table Of Content
- What Is Saline Sonography?
- Why Is an SIS Fertility Test Recommended?
- What Can Saline Sonography Detect?
- How Is Saline Sonography Different From a Normal Ultrasound?
- What Happens During the SIS Procedure?
- When During the Menstrual Cycle Is SIS Usually Done?
- Is Saline Sonography Painful?
- What Happens After Saline Sonography?
- Saline Sonography vs Hysteroscopy
- Does an Abnormal SIS Result Always Mean Surgery?
- Can Saline Sonography Check Fallopian Tubes?
