Can HSG Show Endometriosis? HSG Test Limitations & What It Detects

Can HSG Show Endometriosis? HSG Test Limitations & What It Detects

When I was going through fertility testing before my endometriosis diagnosis, one of the first tests my doctor mentioned was an HSG (hysterosalpingography). 

Like many women dealing with unexplained pelvic pain and fertility issues, I wondered: can HSG show endometriosis? After all, if there was a simple X-ray that could give me answers after years of being dismissed by doctors, wouldn’t that be amazing?

The reality, as I’ve learned through my journey and extensive research, is more nuanced. While HSG cannot directly show endometriosis tissue itself, it can reveal important clues that suggest endometriosis might be present. 

What Is HSG and How Does It Work?

Hysterosalpingography (HSG) is an X-ray procedure that examines your uterus and fallopian tubes. During the exam, a radiologist introduces iodine-based contrast dye through your cervix into your uterine cavity. 

This contrast shows up bright white on X-ray images, allowing doctors to visualize:

• The shape and contour of your uterine cavity
• Whether your fallopian tubes are open (patent)
• The flow of dye through your tubes
• Whether the dye spills freely into your pelvic cavity

The HSG procedure:

1. You lie on an X-ray table with your feet in stirrups
2. A speculum is inserted to access your cervix
3. A thin catheter (cannula) is placed through your cervix
4. Contrast dye is slowly injected while X-ray images are taken
5. The radiologist watches the dye flow through your reproductive tract
6. The procedure typically takes 15-30 minutes

Can HSG Show Endometriosis? 

HSG cannot directly diagnose endometriosis. The HSG procedure is not designed to evaluate the ovaries or to diagnose endometriosis.

Why HSG Cannot Directly Show Endometriosis

HSG is limited because:

• It only visualizes the inside of your uterus and fallopian tubes
• Endometriosis tissue grows outside the uterus
• HSG mainly checks the uterus and tubes. It can’t see endometrial tissue outside the uterus. So, it’s not for diagnosing endometriosis
• The contrast dye doesn’t reach areas where endometriosis typically grows

What HSG actually shows:

• Tubal patency (whether tubes are open or blocked)
• Uterine cavity abnormalities
• Structural problems within the reproductive tract
• Adhesions that might affect tubal function

Does HSG Show Endometriosis Indirectly? Warning Signs to Watch For

While HSG doesn’t show endometriosis directly, this test can reveal several indirect signs that suggest endometriosis might be present.

HSG Findings That May Suggest Endometriosis

Tubal abnormalities:

• Dilated fallopian tubes, lack of contrast spill into the peritoneal cavity, abnormal location of ovaries and/or fallopian tubes
• Hydrosalpinx (fluid-filled, blocked tubes)
• Tubal occlusion or blockage
• Abnormal tubal contours

Contrast flow Patterns:

• No spillage of dye into the pelvic cavity
• Loculated (trapped) contrast in abnormal locations
• Delayed or restricted flow through tubes

Structural changes:

• Deep infiltrating endometriosis as demonstrated by a posterior, midline tubal course
• Abnormal uterine positioning
• Signs of pelvic adhesions affecting tube mobility

The “Endometriosis Pattern” on HSG

Some radiologists recognize what they call a network of fine channels in the fallopian tubes that can suggest tubal endometriosis. However, these findings are not specific to endometriosis and can be caused by other conditions like:

• Previous pelvic infections
• Sexually transmitted infections
• Prior abdominal surgery
• Inflammatory bowel disease
• Other causes of pelvic adhesions

What to Expect from HSG

I haven’t had an HSG myself yet, but based on everything I’ve researched and stories from other women with endometriosis, here’s what you should know:

Pain and Discomfort During HSG

What to expect:

• Moderate to severe cramping during dye injection
• Many patients experience spotting and cramping for up to two days following the exam
• Pain similar to severe menstrual cramps
• Some women report feeling dizzy or nauseous

Pain management tips:

• Take ibuprofen 1 hour before the procedure
• Some doctors prescribe muscle relaxants
• Ask about pain medication options beforehand
• Bring someone to drive you home

What Your Results Might Show

If you have endometriosis, your HSG might show:

• Blocked or partially blocked fallopian tubes
• Abnormal spillage patterns of contrast dye
• Signs of adhesions affecting tube mobility
• Structural abnormalities in the pelvic cavity

Normal HSG results don’t rule out endometriosis. Previous studies have demonstrated that HSG identifies only one-third of the patients with pelvic endometriosis and a high number of patients with normal HSG have pelvic endometriosis and adhesions.

HSG Limitations for Endometriosis Detection

Understanding the limitations of HSG is important for setting realistic expectations.

False Negatives and False Positives

False Negatives (Normal HSG despite endometriosis):

• Up to 67% of women with endometriosis may have normal HSG results
• Early-stage disease often doesn’t affect tube function
• Minimal endometriosis may not cause structural changes

False Positives (Abnormal HSG without endometriosis):

• Studies show that about 39% of HSG tests can be wrong
• Tubal spasms can mimic blockages
• Previous infections can cause similar changes
• Technical factors can affect results

Better Tests for Diagnosing Endometriosis

Since HSG for endometriosis has significant limitations, what are better diagnostic options?

Laparoscopy

Laparoscopy is the top choice for diagnosing endometriosis, with a 90% accuracy rate, because it allows direct visualization of endometriotic lesions. Unlike HSG, which can only show you the inside of your reproductive tract, laparoscopy gives surgeons a complete view of your pelvic cavity. 

They can see endometrial implants wherever they’re hiding, assess how extensive the adhesions are, identify ovarian endometriomas (those chocolate cysts), and evaluate deep infiltrating endometriosis that’s growing into other organs.

What makes laparoscopy so valuable is that it’s both diagnostic and therapeutic. During the same procedure that confirms your endometriosis, the surgeon can often treat what they find by removing implants, breaking up adhesions, and excising cysts. 

It’s like getting answers and treatment in one go, which is why many specialists recommend it for women who have been suffering with unexplained pelvic pain or fertility issues.

Advanced imaging options like transvaginal ultrasound can detect ovarian endometriomas and show structural abnormalities. It’s non-invasive and widely available, though it may miss smaller lesions that laparoscopy would catch. 

MRI is excellent for detecting deep infiltrating endometriosis and can map disease extent before surgery, making it helpful for surgical planning, though it’s more expensive and not always readily available.

There’s also emerging research on blood tests and biomarkers. CA-125 levels can be elevated in some women with endometriosis, and researchers are working on genetic markers and inflammatory marker panels that might one day provide non-invasive diagnosis options.