Patient guide · Gynaecology ultrasound
Saline sonogram (SIS), saline-infusion ultrasound of the uterine cavity — sharper than a standard scan.
A saline sonogram (SIS or SHG) instils sterile saline into the uterine cavity during a transvaginal ultrasound. The saline outlines polyps, fibroids, and any shape problems clearly. It is sharper than a normal pelvic scan, and easier to tolerate than a hysteroscopy.
Reviewed by Pulse Atlas Editorial Board, · Published 2026-07-30 · Next review 2027-07-30 · 4 min read
Key facts
What a saline sonogram is, in six lines.
The essentials — what the test does, how it feels, and where it sits alongside a standard pelvic scan and hysteroscopy.
- 01
Definition
A transvaginal ultrasound done with sterile saline in the uterine cavity — also called SIS or SHG.
- 02
15–20 minute outpatient test
Performed in a single outpatient visit — home the same appointment.
- 03
No sedation, no bowel prep
Awake and comfortable throughout — no fasting or bowel preparation required.
- 04
Sterile saline outlines the cavity
Sterile saline distends the endometrial cavity so its walls and contents stand out.
- 05
Complements transvaginal scan
Sharper than a standard pelvic scan for polyps, submucosal fibroids and septa.
- 06
Complements hysteroscopy
A well-tolerated cavity check that can triage who really needs operative hysteroscopy.
How it’s done
From consultation to plan — what happens, in order.
Seven steps, most of them straightforward. The scan itself is typically 15–20 minutes.
Phase 1 · Before your scan
Consultation and timing
Phase 2 · On the day
~15–20 minutes at the clinic
Phase 3 · After
Report and plan
- 01
Before
Gynaecology consultation
A gynaecologist reviews your symptoms, prior scans and imaging plan before booking.
- 02
Before
Book in follicular phase (days 5–10)
The scan is timed after menstruation and before ovulation for the clearest endometrial view.
- 03
Before
Empty bladder
You will be asked to empty your bladder immediately before the transvaginal scan.
- 04
On the day
Speculum + catheter insertion
A speculum is passed, the cervix cleaned, and a fine catheter placed inside the uterine cavity.
- 05
On the day
Saline infusion + TV scan
Sterile saline is infused slowly while a transvaginal probe images the distended cavity in real time.
- 06
After
Structured report
A written report describes cavity contour, endometrium, polyps, fibroids and any anomalies.
- 07
After
Structured plan
The gynaecology team turns findings into a clear next step — reassurance, hysteroscopy or surgery.
What it shows
The findings a saline sonogram is designed to answer.
Endometrial polyps, submucosal fibroids, cavity anomalies, adhesions and IUD position — the answers that shape a gynaecology plan.
-
Endometrial polyp
A focal outgrowth of endometrium projecting into the cavity — a common cause of intermenstrual bleeding.
-
Submucosal fibroid
A fibroid distorting the cavity — implicated in heavy menstrual bleeding and subfertility.
-
Uterine septum
A congenital fibromuscular partition — associated with recurrent miscarriage and preterm birth.
-
Bicornuate uterus
A congenital Müllerian anomaly with two uterine horns — relevant to pregnancy planning.
-
Intrauterine adhesion (Asherman)
Fibrous adhesions inside the cavity, typically after uterine instrumentation.
-
Endometrial thickening
Diffusely or focally thickened endometrium requiring biopsy or hysteroscopic assessment.
-
IUD position
Confirms coil placement within the cavity or identifies malposition and partial expulsion.
-
Red flag: postmenopausal bleed + thickened endometrium — urgent gynae
Postmenopausal bleeding with a thickened endometrium requires urgent gynaecology review.
Treatment options
What saline sonogram findings typically lead to.
The onward pathway depends on the specific finding — from hysteroscopic day-case surgery to structured gynaecology follow-up and MDT review.
-
Hysteroscopic polypectomy
Day-case hysteroscopic removal of endometrial polyps distorting the cavity.
-
Hysteroscopic myomectomy
Transcervical resection of submucosal fibroids projecting into the cavity.
-
Adhesiolysis (Asherman)
Hysteroscopic division of intrauterine adhesions to restore cavity anatomy.
-
Uterine septum resection
Hysteroscopic metroplasty to divide a septum in selected reproductive indications.
-
IUD adjustment
Repositioning, replacement or removal of a malpositioned intrauterine device.
-
Endometrial ablation
Ablation of the endometrium for heavy menstrual bleeding in appropriate patients.
-
Structured gynae follow-up
A defined follow-up plan — bleeding diary, repeat imaging or interval review.
-
Multi-disciplinary team review
Complex or oncological findings taken to a gynae MDT for coordinated planning.
Red flags
When saline sonogram findings need urgent onward review.
Nine clinical situations where the result carries more weight and needs prompt gynaecology input.
-
Postmenopausal bleeding with thick endometrium
-
Recurrent miscarriage with cavity anomaly
-
Infertility with cavity anomaly
-
Persistent intermenstrual bleeding
-
Retained products of conception
-
Suspected endometrial cancer
-
Post-uterine surgery adhesion
-
Post-Caesarean scar niche
-
Tamoxifen-related endometrial change
Sources
Guidelines this guide is built on.
Reviewed by Pulse Atlas Editorial Board, . Last reviewed 2026-07-30. Next review 2027-07-30.
Frequently asked
Everything we get asked about saline sonogram.
Quick answers on comfort, timing, how it differs from a standard pelvic scan, and when a hysteroscopy is still the right test.
-
What is a saline sonogram (SIS)?
A saline sonogram — also called a saline-infusion sonohysterogram (SIS or SHG) — is a transvaginal ultrasound performed while sterile saline is infused into the uterine cavity through a fine cervical catheter. The saline gently separates the walls of the cavity so polyps, submucosal fibroids and other lesions stand out clearly.
-
How is it different from a standard transvaginal ultrasound?
A standard transvaginal scan images the uterus as it naturally lies, with the cavity collapsed. A saline sonogram distends the cavity with fluid, so subtle intracavitary lesions — such as small polyps or a submucosal fibroid — are much easier to see and measure.
-
Does a saline sonogram hurt?
Most patients describe mild period-like cramping during the infusion that settles within minutes. A simple over-the-counter pain reliever (for example ibuprofen) taken about an hour before the appointment is usually sufficient.
-
When in my cycle should the scan be done?
Ideally in the follicular phase, between days 5 and 10 of your cycle — after your period has finished and before ovulation. This timing gives the thinnest, clearest endometrium and reduces the chance of imaging during an early pregnancy.
-
How quickly are the results available?
Preliminary findings are usually shared verbally at the end of the scan. A structured written report is issued to your gynaecologist within a few working days to guide the next step.
-
When would I still need a hysteroscopy?
A saline sonogram is a diagnostic test, not a treatment. If it identifies a polyp, a submucosal fibroid, adhesions or a septum that need removing or dividing, an operative hysteroscopy is usually recommended as the definitive treatment.
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In practice, in London
Booking saline sonogram privately in London — what actually happens
With saline sonogram, the London question is usually about report turnaround and the radiologist reading it — not whether the scan is available. The wait for saline sonogram on the NHS depends heavily on where you live and how urgently the referral is graded. Central and West London private clinics can normally book within a week, with imaging or a procedure slot to follow shortly after. It’s worth being honest about the reason for going private: usually it’s time, not a fundamentally different test.
A private saline sonogram pathway in London usually looks like this: an initial consultation, any diagnostics booked at a nearby facility (most within Zone 1 or 2), and a written report sent to you and your GP within a few days. The consultants we work with hold NHS posts alongside their private lists, which keeps the standards consistent across both settings. For saline sonogram specifically, the difference between a routine report and a sub-speciality read is where private care earns its keep.
There are a lot of consultants in London who can technically handle saline sonogram. Fewer who do it week in, week out for the exact question you’re bringing. We spend most of our time working out which is which — and being straight when a different test or a different specialist would serve you better. Everything runs to CQC, GMC and Royal College standards; the choice is about fit, not floor.
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