Hysterosalpingogram (HSG): What the Dye Is Trying to Tell Us
If you’re going through a fertility evaluation, there’s a good chance someone has mentioned an HSG, short for hysterosalpingogram. The name sounds intimidating, but the idea behind the test is actually pretty simple: a provider pushes a small amount of dye inside the uterus and watches where it goes. If the dye flows freely through the fallopian tubes and spills into the pelvis, that’s usually a good sign. If it stops somewhere along the way, it may tell us something important about the tubes or the shape of the uterus. Think of it like pouring water through a set of pipes to see whether everything is open and flowing the way it should.
What Is a Hysterosalpingogram?
A hysterosalpingogram (HSG) is a specialized X-ray test used to evaluate the uterus and fallopian tubes.
During the procedure, a small catheter is placed through the cervix and a contrast dye is injected into the uterus. X-ray imaging (fluoroscopy) allows the provider to watch the dye move in real time.
The test helps answer two key questions:
• Are the fallopian tubes open or blocked?
• Does the uterine cavity have a normal shape?
Because the fallopian tubes are where sperm meets egg, making sure they are open is an important part of fertility evaluation.
Why is an HSG Ordered?
An HSG is most commonly ordered during a fertility evaluation, but it can also provide helpful information in other situations.
Common reasons include:
• Difficulty getting pregnant
• History of pelvic infections or sexually transmitted infections
• Prior ectopic pregnancy
• Evaluation before fertility treatments such as ovulation induction or IVF
• Suspicion of uterine abnormalities (such as scar tissue or congenital anomalies)
Sometimes the test is also used to check whether tubal sterilization procedures are still blocking the tubes and how well they are working. However, the procedure that most commonly required this confirmation (Essure) is no longer commercially available, so this is now a much less common reason for performing an HSG.
Who Performs the Test
Depending on where you receive care, different specialists may perform an HSG.
It may be done by:
• A fertility specialist (reproductive endocrinologist)
• A general OB-GYN
• A radiologist in a radiology suite
The technique is largely the same regardless of who performs it, though fertility clinics often perform the procedure in-house while hospitals may send patients to radiology.
How is an HSG Performed?
An HSG is usually performed shortly after your period ends but before ovulation. This timing helps avoid performing the test during an early pregnancy and also allows the study to be done when the uterine lining is at its thinnest, which makes the images clearer and easier to interpret.
The procedure itself typically takes about 10–20 minutes, although the entire process — including positioning, preparation, and imaging — may take longer.
In general, the steps look like this:
• You usually lie on your back on an X-ray table, similar to the position used for a pelvic exam
• A speculum is placed in the vagina
• The cervix is cleaned
• Sometimes the cervix is gently grasped with an instrument to stabilize it, which can make the rest of the procedure easier to perform
• Numbing medicine may be injected into the cervix in some cases
• A small catheter is inserted through the cervix into the uterus
• Contrast dye is slowly injected
• X-ray imaging tracks the dye as it fills the uterus and fallopian tubes
After the images are obtained, the catheter is removed and the images are reviewed and interpreted, with results typically discussed after they have been analyzed.
What Does an HSG Feel Like?
People are often worried about how painful an HSG might be — and that’s a reasonable concern. Experiences vary widely.
For most people, the procedure ranges from mildly uncomfortable to moderately painful.
Many patients describe:
• Mild to moderate cramping
• A pressure sensation when the dye is injected
• A brief but sometimes intense contraction-like pain as the dye moves through the uterus and tubes
However, for others — particularly if the tubes are blocked or sensitive, or if conditions such as adenomyosis, scar tissue, or endometriosis are present — the procedure can be extremely painful, especially if adequate pain control is not used.
Because of this variability, it’s important that people undergoing the test feel informed about what to expect and what options are available for comfort.
Pain Management Options
There is no single standard approach to pain control for HSG, but several strategies can help reduce discomfort. Knowing your options ahead of time can make it easier to advocate for what feels appropriate for you.
Common options include:
• Ibuprofen or other anti-inflammatory medications taken before the procedure
• Local numbing medicine injected into the cervix
For some patients, these measures are enough.
However, some people benefit from stronger pain control, including:
• Anti-anxiety medications
• Stronger pain medications (including narcotics)
• In some settings, moderate sedation or full anesthesia (twilight or general)
Pain control practices vary widely between clinics and hospitals. Advocating for yourself isn’t always easy, but asking about available options ahead of time can help ensure you receive the best support possible during the procedure.
Infection Risk and Antibiotics
Although complications are uncommon, infection is one of the known risks of an HSG.
Because dye is introduced into the uterus and fallopian tubes, bacteria can travel upward and cause infection — pelvic inflammatory disease (PID).
For patients with dilated or damaged fallopian tubes (hydrosalpinx), the infection risk is significantly higher. In these situations, doctors should prescribe preventive antibiotics, often starting around the time of the procedure and continuing for several days afterward.
Ultimately, the provider performing the test will decide whether antibiotics are appropriate based on individual history and imaging findings.
What the Dye Can Tell Us
The movement of contrast dye provides several important clues about reproductive anatomy.
Providers look at:
• How the uterine cavity fills with dye
• Whether the fallopian tubes fill normally
• Whether dye passes through the tubes and out the ends
Together, these findings help determine whether the reproductive tract is structurally open and functioning as expected.
Possible Results
Normal result
The uterus fills smoothly and dye travels through both fallopian tubes with free spill into the pelvis. This suggests the tubes are open.
One tube open, one tube blocked
Dye flows through one fallopian tube but stops in the other. Many people can still conceive naturally with one functioning tube.
Bilateral tubal blockage
Dye stops before reaching the ends of both tubes. This may indicate scarring, prior infection, or other tubal damage.
Hydrosalpinx
A fallopian tube appears dilated and swollen with trapped fluid. This often indicates chronic tubal damage and may affect fertility outcomes.
Uterine cavity abnormalities
Sometimes the dye highlights irregularities inside the uterus such as:
• Polyps
• Fibroids
• Scar tissue
• Congenital uterine differences
Tubal Spasm: A Common False Alarm
One limitation of HSG is something called tubal spasm.
The fallopian tubes contain smooth muscle, and sometimes that muscle tightens during the procedure. When this happens, the dye may appear not to enter the tubes at all, because the spasm occurs right where the tubes connect to the uterus.
This can sometimes create a false impression of tubal blockage, even when the tubes are actually open. When this happens, additional testing may be needed to confirm whether the tubes are truly blocked.
When the Procedure Is Difficult to Perform
Occasionally the procedure cannot be completed smoothly.
Common challenges include:
• Cervical stenosis (a tight cervical opening)
• A cervix that sits at an unusual angle
• Difficulty placing the catheter
In these situations, providers may use smaller catheters, cervical dilation, or specialized instruments to help access the uterine cavity and complete the study. Sometimes medications may also be given beforehand to soften or gently dilate the cervix, such as misoprostol, which can make catheter placement easier in certain cases.
What If an HSG Can’t Be Done?
If HSG isn’t available or is unable to be completed, there are other options to help evaluate tubal patency:
HyCoSy (Hysterosalpingo-contrast sonography)
This ultrasound-based test evaluates the uterus and fallopian tubes using contrast material and ultrasound rather than X-ray. However, many of the same technical challenges that make an HSG difficult — such as cervical access issues — can also make HyCoSy difficult, and the two tests are often used as alternative approaches rather than step-by-step follow-ups.
Chromoperturbation
This test is performed during laparoscopic surgery. Dye is injected through the cervix while the surgeon watches the fallopian tubes directly from inside the abdomen. Chromoperturbation can also allow evaluation for other conditions such as endometriosis or pelvic scar tissue at the same time.
The Bottom Line
A hysterosalpingogram may sound complicated, but at its core the test is simply a way of watching how dye moves through the uterus and fallopian tubes. The information it provides can be extremely helpful in understanding fertility and guiding next steps in care.
At the same time, it’s important to acknowledge that the test can be painful for some people. Being informed about the procedure, understanding the available pain control options, and feeling comfortable speaking up about your needs can make the experience more manageable.
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