Saline Infusion Sonography (SIS) for Uterine Cavity Assessment

What Is Saline Infusion Sonography (SIS)?

Saline Infusion Sonography (SIS) is a specialised ultrasound test used to assess the uterine cavity, meaning the space inside the uterus where the lining sits and where pregnancy implants.

During SIS, a small amount of sterile saline is gently introduced into the uterus via a thin catheter. The saline separates the uterine walls slightly, which can make it easier to see subtle abnormalities on ultrasound.

If you are searching for saline infusion sonography London, you are likely looking for a cavity assessment that is:

• More detailed than standard ultrasound

• Less invasive than procedures that require an operating theatre

• Clinically useful for guiding next steps, especially for bleeding or fertility concerns

Why SIS Is Used

SIS is commonly recommended when symptoms or history suggest that the uterine cavity needs closer assessment, such as:

• Abnormal uterine bleeding, including heavy periods or bleeding between periods

• Suspected endometrial polyps

• Submucosal fibroids that may distort the cavity

• Recurrent miscarriage or fertility concerns where cavity shape matters

• Suspected uterine septum or other cavity irregularities

• Unclear findings on a standard pelvic ultrasound

SIS does not replace a full clinical evaluation. It is used when there is a strong reason to assess the cavity with more detail.

SIS vs Standard Pelvic Ultrasound

A standard pelvic ultrasound is a strong first-line test, but it can miss or under-define issues that sit within the cavity.

SIS can be helpful because it can improve visibility of:

• Small polyps

• Submucosal fibroids projecting into the cavity

• Adhesions or irregular cavity contours

• Lining changes that are subtle on a routine scan

Think of it as ultrasound with a clearer window into the cavity.

SIS vs Hysteroscopy

Both SIS and hysteroscopy can help assess the uterine cavity, but they are not identical.

SIS

• A specialised ultrasound test using sterile saline

• Often used to clarify whether there is a cavity lesion

• Can guide whether further procedures are needed

Hysteroscopy

• A camera examination of the uterine cavity

• Can allow direct visual confirmation

• May allow treatment, such as polyp removal, depending on setting and suitability

A consultant may recommend SIS first when the aim is to clarify anatomy and decide whether hysteroscopy is necessary.

What Happens During SIS

SIS is usually performed as an outpatient procedure and typically involves:

• A brief discussion of your symptoms and timing within your cycle

• A gentle speculum examination

• Placement of a thin catheter through the cervix

• Slow introduction of sterile saline

• Ultrasound imaging to assess the cavity in detail

The scan is performed carefully and gradually. You are not expected to tolerate severe pain. Communication is constant, and you can ask to pause at any time.

What SIS Feels Like

Most women describe:

• Mild to moderate cramping, similar to period pain

• Pressure during catheter placement

• Brief stronger cramps when saline is introduced

Discomfort varies and is influenced by factors such as cervical sensitivity, anxiety, previous procedures, and underlying pelvic pain conditions.

Comfort measures may include:

• Taking simple pain relief beforehand if clinically appropriate

• A calm pace with ongoing explanation

• Adjusting technique to reduce discomfort

If outpatient SIS is not suitable for you, a consultant can discuss alternatives.

Who SIS Is Suitable For

SIS is often suitable for women experiencing abnormal bleeding or fertility concerns, but it may not be appropriate in every situation.

It may be postponed or avoided if there is:

• Suspected pregnancy

• Active pelvic infection

• Certain forms of heavy bleeding at the time of the scan

• Clinical reasons that make another test more appropriate

Your consultant will advise based on your history and current symptoms.

Timing Matters

SIS is typically scheduled at a specific point in the menstrual cycle to improve visibility and reduce the chance of pregnancy. Your consultant will guide you on timing based on your cycle pattern and reason for the scan.

What SIS Can Detect

SIS can help identify issues that may affect bleeding, implantation, or miscarriage risk, including:

• Endometrial polyps

• Cavity-distorting fibroids

• Uterine septum or cavity shape irregularities

• Adhesions or scarring patterns that may require further evaluation

It can also support planning if an intervention is being considered.

Results and Next Steps

A good SIS appointment should end with clear guidance.

Possible outcomes include:

• Reassurance if the cavity appears normal

• A recommendation for hysteroscopy if a lesion needs direct confirmation or treatment

• A targeted plan for managing fibroids or bleeding

• Referral for further fertility assessment if clinically appropriate

You should leave knowing what was found, what it likely means, and what the next step is.

Safety and Aftercare

SIS is widely performed and generally safe, but it is still a medical procedure.

You may experience:

• Light spotting

• Mild cramping for a short period

Seek urgent medical attention if you develop:

• Fever or chills

• Severe or worsening pelvic pain

• Heavy bleeding

• Feeling unwell after the procedure

This information is general and does not replace personalised medical advice.

SIS Scanning at LSDC Healthcare, Central London

At LSDC Healthcare, saline infusion sonography London assessments are offered under specialist care in a discreet Central London setting. The clinical focus is always clarity, patient dignity, and results that translate into a sensible plan.