A normal hysterosalpingogram (HSG) shows a smooth, triangular-shaped uterine cavity with dye flowing freely through both fallopian tubes and spilling out the ends into the pelvic cavity. That spill is the key finding: it confirms your tubes are open, meaning eggs can travel through them and sperm can reach them. If you’re reading your results or preparing for the test, here’s what each part of a normal image actually looks like.
The Uterine Cavity: A Smooth Triangle
The first thing visible on an HSG is the uterine cavity filling with contrast dye. In a normal result, this creates a clear triangular outline on the X-ray. The triangle points downward, with the broad top edge at the fundus (the top of the uterus) and the narrow bottom at the cervical canal. The walls of this triangle should appear smooth, with well-defined margins and no irregular bulges, indentations, or filling defects that might suggest polyps, fibroids, or scar tissue.
The cervical canal, visible at the bottom of the image, may look smooth or slightly ridged. These ridges are normal folds in the cervical lining and don’t indicate a problem. Similarly, faint longitudinal lines running parallel to the uterine cavity can sometimes appear. These are myometrial folds, and they’re a normal variant that shows up on some women’s images.
What Dye Spill Looks Like
After the dye fills the uterine cavity, it enters both fallopian tubes. On the X-ray, you’ll see two thin, bright lines extending outward from the upper corners of the triangle. The tubes themselves are narrow and may appear slightly wavy, which is normal. The critical moment is what happens at the ends of the tubes: the dye should spill freely into the surrounding pelvic space, appearing as a soft, cloud-like spread of contrast on both sides of the image.
This bilateral peritoneal spillage, as your report might call it, is the clearest sign that both tubes are open and functioning. If dye spills from only one side, it could mean the other tube is blocked, though it could also be something far less significant (more on that below). A normal report will typically use phrases like “bilateral tubal patency,” “free spillage of contrast,” or “free flow of contrast medium to the peritoneal cavity.”
When a “Blockage” Isn’t Really a Blockage
One of the most common causes of a false alarm during an HSG is tubal spasm. This happens when the muscle at the point where the tube meets the uterus contracts temporarily, preventing dye from entering. On the image, it can look identical to a true blockage: one tube fills with contrast while the other appears completely obstructed.
Tubal spasm is associated with anxiety, pain during the procedure, or the dye being injected too quickly. Radiologists can often resolve it by pausing the injection for a brief rest, then adding more contrast, or by having you shift position. If the tube fills after these adjustments, spasm was the cause, not a structural problem. If it remains blocked after repeated attempts, a true obstruction is more likely. This distinction matters because a spasm is harmless and temporary, while a genuine blockage may need further evaluation.
Normal Variants That May Appear
Not every uterus is a textbook triangle, and some variations are completely benign. The most common is an arcuate uterus, which shows up as a mild, smooth dip or concavity at the top of the uterine cavity. About 3.9% of women have one. Many radiologists consider it a normal variation rather than an abnormality. It doesn’t affect menstruation, fertility, or pregnancy outcomes, and it doesn’t require any treatment.
If your report mentions an arcuate uterus, it’s essentially saying your uterus has a slight indent at the top instead of a perfectly flat or rounded fundus. The shallow dip doesn’t significantly change the overall shape, and the rest of the HSG findings (smooth walls, bilateral spill) still define the result as normal.
Understanding Your Report
HSG reports use specific radiology language that can sound intimidating. Here’s what the most common normal findings mean in plain terms:
- Triangular uterine cavity with smooth margins: Your uterus has a normal shape with no growths or irregularities.
- Bilateral tubal patency: Both fallopian tubes are open.
- Free peritoneal spillage: Dye flowed all the way through the tubes and out the ends, confirming they’re clear.
- Opacification of both fallopian tubes: The dye successfully filled both tubes so they were visible on X-ray.
- No filling defects: Nothing is blocking or distorting the inside of the uterine cavity.
If all of these phrases appear in your report, your HSG is normal.
The Procedure Itself
An HSG is a quick imaging test, typically finished within 15 to 30 minutes. A thin catheter is inserted through the cervix, and contrast dye is slowly pushed into the uterus while a series of X-rays are taken in real time. You’ll likely feel menstrual-like cramping as the dye fills the cavity and tubes, which can range from mild to moderately uncomfortable. Some women also feel brief dizziness.
Afterward, mild cramping and light spotting for a day or so are completely normal. Over-the-counter pain relief like ibuprofen helps with any lingering discomfort. You’ll want to use pads rather than tampons and avoid intercourse for 48 hours.
The Fertility Boost After an HSG
One of the more surprising findings about HSG is that the procedure itself may improve your chances of getting pregnant in the months that follow, even if your results are normal. The leading theory is that flushing dye through the tubes clears minor debris or mucus that could interfere with conception.
A large study published in Human Reproduction Open found that the type of dye used matters. Women who had their HSG with oil-based contrast had a 39.7% ongoing pregnancy rate within six months, compared to 29.1% for those who received water-based contrast. Live birth rates followed the same pattern: 38.8% versus 28.1%. For some women, the estimated increase in pregnancy chances from oil-based contrast was as high as 13 percentage points. Not every clinic uses oil-based dye, so if you’re interested, it’s worth asking which type will be used before your procedure.