Ovarian Cyst on Ultrasound: What Does the Report Mean?

An ovarian cyst on ultrasound means the scan found a fluid-filled sac on or in an ovary. These are very common, and the NHS says most cause no symptoms and go away within a few months without treatment. The next step depends on what the cyst looks like, your symptoms and whether you have been through menopause.

This guide is for adults reading an ultrasound report that mentions an ovarian cyst. It explains common terms and the usual questions. It cannot tell you what your own cyst is or how quickly you need follow-up.

A cyst can twist the ovary and cut off its blood supply (ovarian torsion), or burst and bleed (rupture). Both can need emergency surgery. Call local emergency services or go to the nearest emergency department if you have:

• Sudden, severe pain in the lower tummy or pelvis, especially with nausea or vomiting.
• Severe pain with fever.
• Feeling faint, dizzy or weak, rapid breathing, or cold and clammy skin.
• Severe vaginal bleeding with feeling faint.
• Pelvic pain with a possible pregnancy: ectopic pregnancy also needs urgent assessment.
• Do not wait for a planned follow-up scan if any of these happen. A previous 'simple cyst' report does not rule out a new emergency.

Functional cysts form as part of the menstrual cycle. Cleveland Clinic describes two kinds: a follicular cyst, when the follicle does not release its egg and keeps growing, and a corpus luteum cyst, when the structure left after ovulation fills with fluid. They are usually harmless and tend to shrink on their own over a few months.

Other, less common cysts come from abnormal cell growth or other conditions. These include dermoid cysts (which can contain tissue such as hair), cystadenomas, and endometriomas, which are linked to endometriosis. Most of these are also non-cancerous.

Many cysts are found by chance on a scan done for another reason. When cysts do cause symptoms, the NHS lists pelvic pain that can range from a dull ache to sudden sharp pain, pain during sex, changes in bowel or bladder habits, changes to periods, bloating and feeling full quickly. The NHS also notes that ovarian cysts usually do not affect fertility. Tell your clinician about any of these symptoms, even mild ones, because they help decide whether watching and waiting is reasonable.

Reports often describe how a cyst looks. A 'simple' cyst generally means a thin-walled sac filled with clear fluid. Functional cysts are sometimes called simple cysts. A 'complex' cyst has other features, such as internal echoes, separations or solid areas. Many complex cysts are still benign, for example a bleeding functional cyst, a dermoid or an endometrioma, but they are more likely to need a repeat scan, further imaging or a specialist opinion.

Ask your clinician to explain the exact words in your report, the size measured and whether the description changes the plan. Do not try to judge cancer risk from the wording yourself.

Some reports include an O-RADS score. The American College of Radiology describes O-RADS as a standardised system for classifying ovarian and adnexal findings into risk categories, with an ultrasound version and an MRI version. It helps radiologists and clinicians describe findings consistently and choose the next step.

Not every service uses O-RADS, and the category is read together with your age, symptoms and menopausal status. If your report gives a score, ask what that category means for your follow-up and whether any further imaging is advised.

Often, yes. The NHS says a repeat scan may be done a few weeks later to check whether the cyst has gone, or you may be referred to a gynaecologist. Cleveland Clinic describes monitoring with a repeat ultrasound a few weeks or months later. Healthdirect notes that removal may be considered if a cyst has not gone after 3 months, is over 6 cm, keeps growing, causes pain or may be cancerous. Thresholds and timing differ between services.

After menopause, cancerous cysts are more likely, although still uncommon. The NHS says regular ultrasounds and blood tests over about a year are usually advised in that situation. Before menopause, cancerous cysts are rare, and surgeons usually try to preserve the ovary and fertility if surgery is needed.

CA-125 is a blood test sometimes ordered when a cyst raises concern, particularly after menopause. The National Cancer Institute lists it as a marker that can help with diagnosing ovarian cancer and following treatment. It is not a stand-alone answer.

CA-125 can be raised by non-cancer conditions, including endometriosis, liver disease, fluid around the lungs or abdomen and early pregnancy, according to the NCI. The NHS adds fibroids, pelvic infection and periods. A normal level also does not rule everything out. Laboratories set their own reference ranges, so ask how your result was interpreted alongside the scan.

Take the full ultrasound report, the date of your last period and any blood results to the appointment.

• What type of cyst does this look like, and how big is it?
• Was it described as simple or complex, and what features were seen?
• Was an O-RADS category given, and what does it mean for me?
• Do I need a repeat scan, and when? Who will book it?
• Is a CA-125 test or other imaging useful in my situation, and how will the result be read?
• What symptoms mean I should go to emergency care rather than wait?

On SameCase, patients and verified doctors share de-identified cases. Reading how people with a similar report, age or menopausal status described their follow-up can help you spot questions to bring, such as how the cyst was described or why a repeat scan was timed as it was.

Other people's cases cannot tell you what your cyst is or whether it needs surgery. Use them to prepare, then decide with your own clinician. If your main concern is severe period pain with a normal scan, our guide on period pain with a normal ultrasound covers that question.