Ultrasound can be an important part of investigating suspected endometriosis, but it does not show every type of disease in every person.

It may help identify endometriomas, some deep endometriosis, signs of adhesions, or other conditions that could be causing symptoms. But a normal ultrasound does not always mean endometriosis is not present.

What is an ultrasound?

An ultrasound scan uses sound waves to create images of organs and tissues inside the body.

For suspected endometriosis, ultrasound may be:

  • transvaginal, where a small probe is placed inside the vagina
  • transabdominal, where the probe is moved over the lower abdomen
  • transrectal in selected cases, depending on symptoms and local specialist practice

You should be told what type of scan is being offered and why. You can ask questions and you can decline an internal scan if it is not suitable for you.

What ultrasound may show

Ultrasound may help identify:

  • ovarian endometriomas
  • some deep endometriosis
  • signs of disease involving bowel, bladder or ureter
  • reduced organ movement that may suggest adhesions
  • ovarian cysts
  • fibroids
  • adenomyosis signs
  • other pelvic conditions

The scan can help guide next steps, including treatment, referral or further imaging.

What ultrasound may miss

Ultrasound may not show all endometriosis.

It may miss:

  • superficial lesions
  • small lesions
  • subtle disease
  • disease in difficult-to-see areas
  • extra-pelvic disease
  • disease when the scan is not performed or interpreted by someone with endometriosis expertise

This is why symptoms still matter, even when imaging is normal.

Specialist ultrasound matters

A routine pelvic ultrasound may not be the same as a specialist endometriosis ultrasound.

Specialist imaging may involve looking carefully for signs of deep endometriosis, organ movement, bowel involvement, bladder involvement, endometriomas and adhesions.

If your symptoms continue and your first scan is normal, ask whether specialist ultrasound or MRI would be appropriate.

Does a normal ultrasound rule out endometriosis?

No.

A normal ultrasound does not always rule out endometriosis. It may mean that no endometriosis was seen on that scan, not that endometriosis is impossible.

If symptoms continue to affect your life, ask what the next step should be.

Preparing for an ultrasound

You may want to ask:

  • What type of ultrasound am I having?
  • Is it transvaginal, transabdominal or both?
  • Do I need a full bladder?
  • Will the scan look for signs of endometriosis specifically?
  • Who will report the scan?
  • Will bowel, bladder, ureter or endometrioma signs be considered?
  • What happens if the scan is normal but symptoms continue?

Use the Prepare for Appointment Tool

Before discussing scan results, use our Prepare for Appointment Tool to organise your symptoms and questions.

This can help you explain why further assessment may still be needed if symptoms continue despite normal imaging.

Final reminder

Ultrasound can be useful, but it is not perfect.

Normal ultrasound results should not be used to dismiss severe, persistent or life-disrupting symptoms.