What it means
After an ovary releases an egg, the empty follicle turns into the corpus luteum, Latin for yellow body. It makes the hormone progesterone, which prepares the uterus for a possible pregnancy. On ultrasound it looks like a small cyst with a thick, wavy wall. Doppler shows a ring of blood flow around it, sometimes called a ring of fire. It may contain a little blood.
When it matters
A corpus luteum means the ovary is working normally. It usually fades within about two weeks if no pregnancy occurs, and in early pregnancy it lasts longer to support it. It can fill with blood and cause pain, and less often it bursts. It usually needs no treatment. If the picture is unclear, a repeat scan after the next period may be offered. On PET scans it can take up tracer, a normal finding before menopause.
Questions to ask your doctor
- Is this a normal corpus luteum, or a cyst that needs another look?
- Does the timing in my cycle fit with what the scan shows?
- Should I have a repeat scan after my next period?
