In short
A pelvic scan reports measurements that change across the menstrual cycle, which is why the same number can be normal one week and abnormal the next. The date of your last period is part of the result.
Emergency if: Sudden severe one-sided pelvic pain with faintness, vomiting or shoulder-tip pain — this can be a twisted ovary or a ruptured ectopic pregnancy, go to an emergency department now.
On your report
Beta-hCG (Non-Pregnancy / Tumor Marker Use), AMH (Anti-Müllerian Hormone), FSH (Follicle-Stimulating Hormone), LH (Luteinizing Hormone) +3 more
On this page
01
Two ways of scanning, and why it matters
A pelvic ultrasound can be done through the abdomen, which needs a full bladder as an acoustic window, or transvaginally, which places the probe much closer to the organs and gives considerably more detail. Reports usually state which was used, and that determines how much weight the measurements carry.
A transabdominal scan in someone with a partly filled bladder can miss a small polyp or misjudge the endometrium. If a report notes limited views or suboptimal visualisation, the finding is provisional — and that is a reason to repeat with better conditions rather than to act on the number.
02
Endometrial thickness depends on the day
The endometrium is the uterine lining, and it thickens through the cycle by design: thin just after a period, thicker around ovulation, thickest before the next period. A measurement is therefore uninterpretable without knowing the cycle day, which is why you are asked for the date your last period started.
After menopause the situation is different and simpler, because the lining should be thin and stay thin. A thickened endometrium in a postmenopausal woman, particularly with any bleeding, is the finding that leads to further assessment. Postmenopausal bleeding is investigated regardless of what the scan shows.
03
Follicles, cysts and the difference
The ovaries normally contain small fluid-filled follicles, and each cycle one grows and releases an egg. A follicle that keeps growing or fails to release becomes a functional cyst — which is why simple cysts of a few centimetres are extremely common, usually cause nothing, and generally resolve on their own over a couple of cycles.
Reports distinguish simple cysts, which are thin-walled and purely fluid, from complex ones containing solid areas, septations or internal echoes. Simple cysts are usually followed with a repeat scan; complex or larger ones prompt closer assessment. Endometriomas and dermoid cysts have characteristic appearances and are often named directly.
04
Polycystic ovaries are not the same as PCOS
A report describing polycystic-appearing ovaries means many small follicles are visible. This appearance is common and is found in people with entirely regular cycles and no other features — it is a description of an image, not a diagnosis.
Polycystic ovary syndrome is a clinical diagnosis requiring a combination of features, typically irregular or absent ovulation, signs or blood tests indicating excess androgens, and the ovarian appearance — with other causes excluded. Being told you have polycystic ovaries on a scan is therefore not the same as being told you have the syndrome, and the distinction changes what, if anything, needs doing.
05
Fibroids, adenomyosis and free fluid
Fibroids are reported by number, size in millimetres and — most usefully — by position, since a small fibroid distorting the cavity can cause far more bleeding than a large one sitting on the outer wall. Keeping the measurements between scans is what shows whether they are growing.
Adenomyosis, where lining tissue grows into the muscle wall, is suggested by a bulky uterus with a poorly defined junctional zone. A small amount of free fluid in the pelvis is a normal finding around ovulation and usually needs no action; a larger collection, particularly with pain, is followed up.
06
What the scan cannot settle
Ultrasound cannot tell you whether the fallopian tubes are open — that needs a dedicated test — and it cannot reliably diagnose endometriosis outside of an endometrioma, so a normal pelvic scan does not exclude it. Nor does the appearance of the ovaries measure fertility on its own.
The report's value is greatest when read with the cycle day, your symptoms and any previous scans together. If a finding is described that you do not understand, ask specifically whether it changes anything — a great many pelvic ultrasound findings are normal variants that need naming but not treating.
When to act
Routine — see a doctor
A simple ovarian cyst of a few centimetres with no symptoms: this usually resolves on its own, and is followed with a repeat scan rather than treated.
Same-day — call promptly
Any bleeding after menopause, a thickened lining reported after menopause, a rapidly enlarging fibroid, or a complex cyst.
Emergency — act now
Sudden severe one-sided pelvic pain with faintness, vomiting or shoulder-tip pain — this can be a twisted ovary or a ruptured ectopic pregnancy, go to an emergency department now.
Values mentioned in this story
Each one opens a visual guide with its normal range and what moves it — upload a report and we place your own numbers on the same scale.
Sources
- Ultrasound — MedlinePlusmedlineplus.gov
- Ultrasound Scan — NHSnhs.uk
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