A hysterosalpingogram, usually just called an HSG, is an X-ray that shows two things: the shape of the inside of your uterus, and whether your fallopian tubes are open. It is one of the standard parts of a fertility evaluation, and for many people it is the first procedure they have.
What it shows
Contrast dye is passed into the uterine cavity and X-ray images are taken as it moves. Two findings come out of it.
- The shape of the uterine cavity. The dye outlines the inside of the uterus, which can reveal a polyp, a fibroid pressing into the cavity, scar tissue, or a congenital variation such as a septum.
- Whether the tubes are open. If the tubes are open, dye passes along them and spills out of the far end into the abdomen. If one or both are blocked, the dye stops.
Both matter for different reasons. A tube that is blocked at the far end can prevent the egg and sperm from ever meeting, which is a reason IVF may be recommended rather than IUI. A cavity finding may be treatable before any treatment cycle begins.
What it does not show
An HSG is a test of plumbing, not of everything. It does not assess egg quantity or quality — that is what AMH, antral follicle count and day-3 bloodwork are for. It does not diagnose endometriosis, and it does not show adhesions on the outside of the tubes or ovaries. A tube that is open on an HSG is also not necessarily a tube that is working normally.
It tells you nothing about sperm, so it is done alongside rather than instead of a semen analysis.
When in your cycle it is done
An HSG is scheduled in the first half of the cycle — after menstrual bleeding has stopped and before ovulation. The reason is simple: it confirms you are not pregnant at the time of the X-ray.
Your physician will tell you where yours is scheduled and what to do beforehand. Ask about pain relief in advance rather than on the day.
What it feels like
Most people describe cramping, strongest in the moment the dye passes through, easing within minutes. Some feel very little. Light spotting afterwards is common and settles within a day or so. It is a short procedure and you are awake for it.
If you have had a difficult experience with a previous HSG, or you are anxious about it, say so beforehand — it changes how your physician prepares you for it rather than being something to get through silently.
Is there a fertility benefit afterwards?
You may read that pregnancy rates rise in the months immediately after an HSG, particularly where oil-based contrast is used. That effect has been described in the literature and it is a real question to raise. Whether it applies in your situation, and which contrast is appropriate, is a decision for your physician rather than something to assume from the procedure itself.
Other ways of looking at the uterus
An HSG is not the only option, and it is not always the right first one. A saline infusion sonogram uses ultrasound with fluid rather than X-ray and contrast, and hysteroscopy looks at the cavity directly with a camera. Those are part of the workup for recurrent pregnancy loss. Which test is appropriate depends on what the rest of your evaluation shows, and is determined by your physician.
If you have already had an HSG elsewhere, bring the images and the report. We generally will not repeat recent testing — see fertility testing and diagnosis for what a full evaluation involves, and fertility second opinion if you have been treated elsewhere.
Common questions
What does an HSG test for?
An HSG shows the shape of the uterine cavity and whether the fallopian tubes are open. Contrast dye is passed into the uterus and X-ray images are taken as it moves; dye spilling from the far end of a tube indicates that the tube is open.
When in my cycle should an HSG be done?
In the first half of the cycle, after menstrual bleeding has stopped and before ovulation, so that a pregnancy is not in progress at the time of the X-ray.
Does an HSG hurt?
Most people describe cramping that is strongest as the dye passes through and eases within minutes, and some feel very little. Light spotting for a day afterwards is common. Ask your physician about pain relief in advance rather than on the day.
Can an HSG tell me about my egg count?
No. An HSG assesses the uterine cavity and the fallopian tubes. Egg quantity is assessed with AMH, antral follicle count and day-3 bloodwork, which are separate tests.
Do I need to repeat an HSG I had at another clinic?
Usually not. Bring the images and the report. We generally will not repeat recent testing and will use it to move you toward treatment.
Your initial consultation is free for all new patients, and we bill health insurance where you have coverage that applies. Call 212-685-2229 or send us a message to arrange a visit.
Book an appointment
Consultation is free for new patients; we bill health insurance where you have coverage that applies.