HSG Test: What It Shows, What It Cannot, and What Happens Next

A hysterosalpingogram (HSG) is an X-ray taken while contrast dye is passed through the cervix into the uterus. The dye fills the uterine cavity, travels along the fallopian tubes, and spills out of the ends if the tubes are open.

That gives two pieces of information, and essentially only two:

• Whether each fallopian tube is open, blocked, or partly blocked
• The shape and outline of the uterine cavity — septa, polyps, submucosal fibroids distorting the cavity, scarring, and congenital shape variations

For tubal patency it performs well. A comparative study of HSG against diagnostic hysteroscopy reported sensitivity of 95.8% and specificity of 92.3% for tubal patency assessment.

Everything else people hope an HSG will settle, it cannot.

No. An HSG cannot diagnose endometriosis or assess how severe it is.

This is the single most common misunderstanding about the test, and it matters — a normal HSG is often read as 'nothing wrong', when endometriosis was never something the test could have found.

The reason is anatomical. An HSG only images spaces the dye reaches: the inside of the uterus and the inside of the tubes. Endometriosis is disease on the outside of the pelvic organs — on the peritoneum, ovaries, and the outer surface of the bowel and bladder. The dye never touches it.

An HSG can occasionally show findings that raise suspicion of pelvic disease, without diagnosing it:

• Tubal occlusion, particularly at the outer end
• Loculated dye spill, suggesting adhesions holding the tube in place
• A tube that is fixed and does not move freely

These are indirect hints. Laparoscopy with visual inspection remains the reference standard for diagnosing endometriosis, and MRI is used to assess deep disease and endometriomas. If endometriosis is the question, the HSG is the wrong test.

No. An HSG does not image the ovaries.

The ovaries sit outside the uterus and tubes and are not connected to them by any open channel. Contrast dye passes from the tube directly into the abdominal cavity; it never enters an ovary. The X-ray also does not show soft tissue well enough to outline one.

An HSG likewise cannot show:

• Ovarian cysts, endometriomas, or polycystic ovary morphology
• The muscular wall of the uterus, so intramural fibroids that do not distort the cavity are invisible
• Egg quality, ovarian reserve, or whether you are ovulating
• Whether an embryo can implant

For ovaries and cysts, the correct test is a transvaginal ultrasound. It is quicker, cheaper, uses no radiation, and is usually done alongside an HSG rather than instead of it.

An HSG is scheduled in the follicular phase — generally between day 5 and day 12 of a 28-day cycle, once menstrual bleeding has stopped.

Two reasons drive that window:

• Pregnancy is very unlikely to have occurred yet, so there is no risk of exposing an early pregnancy to radiation
• The endometrium is still thin, so the cavity outline is easier to read and less likely to produce a false filling defect

If your cycles are irregular, the clinic will usually confirm you are not pregnant before proceeding rather than counting days.

Cramping is common, both during the procedure and for a short time afterwards. Most people describe it as period-like. It is usually brief — from about five minutes to a few hours.

The discomfort comes from three separate things:

• Instrumentation of the cervix to place the catheter
• Distension of the uterus as dye is injected
• Irritation of the peritoneum when dye spills out of the tube ends

Pain tends to be worse when a tube is blocked, because pressure builds instead of the dye escaping. An over-the-counter NSAID taken roughly an hour beforehand is commonly advised and is reasonable for most people. Ask your clinic what they recommend, since it depends on your history.

Light spotting for a day or two afterwards is expected. Fever, heavy bleeding, or worsening pain is not, and should be reported the same day.

An HSG is a diagnostic test, but it has a documented side effect: pregnancy rates rise in the months immediately after it.

The H2Oil trial randomized 1,108 infertile women to oil-based or water-based contrast. Within six months, 39.7% of the oil group had an ongoing pregnancy compared with 29.1% of the water group — a relative risk of 1.37 (95% CI 1.16-1.61). Live birth rates followed the same pattern, 38.8% against 28.1%.

The likely mechanism is mechanical. Flushing the tubes clears debris and mucus that can obstruct the passage of egg, sperm, or embryo without fully blocking the tube.

Two things worth knowing about this effect:

• It is strongest in the first months and narrows over time — at three years the difference had fallen to 77% versus 71%
• It is most relevant when the tubes turn out to be open and the infertility is otherwise unexplained

If you are choosing between contrast types, it is a reasonable thing to raise with your clinic. Availability and local protocol vary.

HSG reports use a small vocabulary. Broadly:

• Bilateral spill / free spill — both tubes are open
• Unilateral spill — one tube is open, one is not
• Proximal occlusion — blockage where the tube meets the uterus
• Distal occlusion or hydrosalpinx — blockage at the outer end, sometimes with the tube dilated and fluid-filled
• Filling defect — something occupying the cavity, such as a polyp or submucosal fibroid

Proximal occlusion deserves caution. Tubal spasm during the test can mimic a blockage, so a proximal block on a first HSG is not always a true one and is often re-checked before any decision is made.

A hydrosalpinx is treated differently from other blockages, because fluid draining back into the uterus reduces IVF success. It is usually addressed before transfer.

Which test follows an HSG depends on what it found and what question remains:

• HyCoSy or HyFoSy — an ultrasound-based tubal patency test using contrast, with no X-ray exposure, and it images the ovaries at the same time
• Saline infusion sonography — better than HSG for polyps and cavity assessment, but does not reliably assess the tubes
• Hysteroscopy — direct view inside the cavity, and can treat a polyp or septum in the same session
• Laparoscopy — the reference standard for endometriosis and pelvic adhesions, and the only one of these that diagnoses endometriosis

A normal HSG is genuinely useful information: it means the anatomy the test can see is not the obstacle. It does not mean nothing is wrong.

An HSG is an outpatient procedure. From arrival to leaving is usually under an hour, with the imaging itself taking around five to ten minutes.

1. You change and lie on an X-ray table, positioned as for a smear test
2. A speculum is inserted and the cervix is cleaned
3. A thin catheter is passed through the cervix into the uterus — this is where most of the cramping starts
4. The speculum is usually removed, and contrast dye is injected slowly through the catheter
5. X-ray images are taken as the dye fills the cavity and moves along the tubes
6. The catheter is removed and you rest briefly before leaving

Practical points that are easy to overlook:

• Bring a sanitary pad — dye leaks out afterwards and spotting is common
• Arrange to have the rest of the day light, though most people function normally
• You can usually drive yourself unless you have been given sedation
• Ask whether the radiologist will talk you through the images as they appear; many will

Some centers in India perform HSG under short sedation on request, particularly where a previous attempt was abandoned for pain. It is worth asking in advance rather than on the day, as it changes fasting instructions and whether you can drive.

HSG is a low-risk procedure, but it is not risk-free.

The recognized risks:

• Pelvic infection — uncommon, and the main reason the test is avoided if there is active infection or unexplained pelvic pain. Some clinics give prophylactic antibiotics, particularly where tubal damage is suspected
• Allergic reaction to contrast — rare; tell the team about any previous contrast or iodine reaction
• Fainting or a vasovagal episode during cervical instrumentation
• Radiation exposure — low, and the reason for the early-cycle timing

Contact your clinic the same day if you develop:

• Fever or chills
• Bleeding heavier than a period
• Pain that worsens rather than settles over the hours afterwards
• Foul-smelling discharge

Ordinary spotting for a day or two, and cramping that eases through the afternoon, are expected and do not need reporting.

These tests are frequently presented as alternatives when they answer different questions:

• HSG — tubal patency and cavity outline. Widely available, inexpensive, uses X-ray. Carries the post-test fertility effect
• HyCoSy or HyFoSy — tubal patency by ultrasound with contrast. No radiation, and it images the ovaries and uterine wall in the same appointment. More operator-dependent
• Saline infusion sonography — best for polyps and cavity detail; does not reliably assess tubes
• Hysteroscopy — direct view of the cavity, and treatment in the same session. Says nothing about the tubes beyond their openings
• Laparoscopy — the reference standard for endometriosis and adhesions, and the only one that diagnoses endometriosis. Surgical, under general anaesthetic

A reasonable rule: if the question is 'are the tubes open', an HSG or HyCoSy answers it. If the question is 'do I have endometriosis', neither does.

Where both HSG and HyCoSy are available, cost and radiation are the usual deciding factors, alongside whether the ovaries also need assessing.

A common question, and a reasonable one given the post-HSG fertility effect.

Most clinics are comfortable with intercourse in the same cycle once bleeding and cramping have settled, provided the test was uncomplicated and there is no sign of infection. The timing of the test in the follicular phase is deliberately before ovulation, so the fertile window is still ahead of you.

Where clinics do advise waiting a cycle:

• If prophylactic antibiotics were given for suspected tubal damage
• If there was significant pain, difficulty with the procedure, or bleeding
• If a hydrosalpinx was found, since that changes the plan anyway
• Where a treatment cycle is being scheduled and they want a clean baseline

Ask before you leave rather than afterwards. Practice varies, and the answer depends on what the test showed as much as on the test itself.

If the flushing effect is part of why you are having the test, the months immediately following are when it is strongest, so there is little reason to delay unnecessarily.

An HSG produces images that are interpreted in the room, which makes it one of the few tests where you can get answers immediately.

Before the procedure:

• Will oil-based or water-based contrast be used, and is there a choice?
• Should I take an NSAID beforehand, and how long before?
• Will antibiotics be given, and why or why not?
• Is sedation available if I need it?

Afterwards:

• Did dye spill freely from both tubes?
• Was the uterine cavity outline normal?
• If a blockage was seen, was it proximal or distal — and could spasm explain a proximal one?
• Does anything here need a further test, and which one?
• Can we try this cycle?

Request a copy of the report and the images. If a second opinion or a change of clinic follows later, having the original images avoids repeating the test.

• Tubal Blockages: How They Are Diagnosed and When Surgery Helps
• Fertility Tests for Women: What Each One Checks, and When
• IUI vs IVF — Which Treatment Is Right for You? (2026)
• Hysteroscopy in Infertility Workup
• Top Questions Couples Ask Fertility Doctors
• How to Prepare for a Fertility Test
• What to Expect in a Fertility Consultation

Comparing centres locally helps: our directory covers fertility clinics in Basaveshwar Nagar, each with an IVY Score built from the same five signals, alongside the other 37 areas of the city.