Pelvic ultrasound
A pelvic ultrasound is the main imaging test for abnormal bleeding. It shows fibroids, polyps, adenomyosis, and the thickness of the uterine lining, and it uses no radiation.
What to expect
Most exams have two parts. A transabdominal scan is done over the lower belly, sometimes with a full bladder. A transvaginal scan uses a slim probe placed in the vagina for a closer view. The transvaginal part is usually more informative and generally not painful. The whole exam takes about 20 to 30 minutes.
Timing
If you still have periods, your physician may ask you to schedule the scan soon after your period ends. The lining is thinnest then, which makes polyps easier to see. Do not delay a scan for this if you are bleeding heavily or continuously.
Saline infusion ultrasound
If the standard scan is unclear, a saline infusion sonohysterogram fills the uterus with a small amount of sterile fluid during the scan. It outlines polyps and fibroids inside the cavity. Some cramping is common.
After menopause
The key measurement is the thickness of the lining. A lining of 4 mm or less makes cancer unlikely. A thicker lining, or bleeding that continues, leads to a biopsy.
MRI
MRI is used when ultrasound is not enough, for example to map fibroids before surgery or to clarify adenomyosis.
Sources
- American College of Obstetricians and Gynecologists. Practice Bulletin No. 128: Diagnosis of abnormal uterine bleeding in reproductive-aged women. Obstet Gynecol. 2012;120(1):197–206 (reaffirmed).
- American College of Obstetricians and Gynecologists. Committee Opinion No. 734: The role of transvaginal ultrasonography in evaluating the endometrium of women with postmenopausal bleeding. Obstet Gynecol. 2018;131(5):e124–e129.