HSG Explained
(Hysterosalpingogram)
"A simple test that can reveal whether your fallopian tubes are open—or whether they may be preventing pregnancy."
What is an HSG?
An HSG (Hysterosalpingogram) is a special X-ray used to examine:
Your womb (uterus)
Your fallopian tubes
Whether the tubes are open or blocked
During the test, a doctor gently places a small catheter through the cervix and injects a special dye into the uterus.
As the dye flows, X-ray images are taken.
If the dye passes freely through both tubes and spills into the pelvis, the tubes are considered open.
If the dye stops, it may indicate a blockage.
Why is an HSG done?
An HSG is commonly recommended if you've been trying to conceive without success.
It helps doctors look for problems that may not be visible on routine scans, including:
• Blocked fallopian tubes
• Hydrosalpinx (fluid-filled tubes)
• Scar tissue
• Congenital abnormalities of the uterus
• Polyps or fibroids affecting the uterine cavity
What does a normal HSG look like?
A normal result means:
✓ The dye fills the uterus normally.
✓ The dye travels through both fallopian tubes.
✓ The dye spills freely from the ends of the tubes into the pelvis.
This suggests that sperm and egg should be able to meet naturally.
What if one tube is blocked?
If one tube is blocked:
Pregnancy can still happen naturally.
The open tube may still collect an egg from either ovary.
Fertility may simply be reduced rather than impossible.
Your doctor may investigate why the blockage occurred.
What if both tubes are blocked?
If both tubes are blocked, the egg and sperm cannot meet naturally.
Common causes include:
Previous pelvic infection
Endometriosis
Previous surgery
Pelvic inflammatory disease (PID)
Hydrosalpinx
Your fertility specialist will discuss treatment options depending on the cause.
What is hydrosalpinx?
Hydrosalpinx occurs when a fallopian tube becomes blocked and fills with fluid.
The fluid can:
• Damage embryos
• Reduce implantation
• Lower IVF success rates
Many women have no symptoms at all.
Others experience:
Pelvic pain
Discomfort during periods
Persistent vaginal discharge
Or no symptoms whatsoever
Can an HSG detect hydrosalpinx?
Yes—often.
If dye enters a swollen tube but cannot spill out normally, the tube may appear enlarged and swollen on the X-ray.
Sometimes hydrosalpinx is obvious.
Sometimes additional investigations such as ultrasound or laparoscopy are needed.
Does an HSG hurt?
Experiences vary enormously.
Some women feel:
✓ Mild period cramps.
Others experience:
✓ Moderate cramping for a few minutes.
A smaller number find it quite painful, particularly if there is a blockage.
The discomfort usually settles quickly after the procedure.
Taking simple pain relief before your appointment is often recommended.
Can an HSG improve fertility?
Surprisingly...sometimes.
Some studies suggest that the dye may flush minor debris or mucus from the tubes.
Pregnancy rates can be slightly higher during the first few months after an HSG, particularly when oil-based contrast is used in selected situations.
However, this isn't the main purpose of the test.
Are HSGs always accurate?
No.
Occasionally a tube appears blocked because it briefly goes into spasm during the procedure.
This is known as a tubal spasm.
For this reason, doctors sometimes recommend repeating the test or performing a laparoscopy if the findings don't fit the clinical picture.
Questions you may wish to ask your doctor
• Were both tubes definitely open?
• Was dye seen spilling freely?
• Was there any sign of hydrosalpinx?
• Was there any suggestion of scar tissue?
• Do I need further investigations?
• If a tube is blocked, what caused it?
• Would laparoscopy provide more information?
A gentle reminder
An HSG tells us about the shape of the womb and whether the fallopian tubes are open.
It cannot diagnose everything.
A normal HSG does not rule out endometriosis, problems with egg quality, ovulation issues or sperm factors.
It is one important piece of the fertility puzzle—not the whole picture.
My personal fertility journey is told in full in my book, Twenty Years to You. The articles on this website focus on providing clear, evidence-based information to help you understand your own fertility journey.