Did they say the word "corpus luteum" at all?

A corpus luteum cyst, as someone said above, is a completely normal state of early pregnancy. After you have ovulated the corpus luteum (dead egg sack) remains and produces progesterone which prevents you bleeding (AF) to give the egg a chance to be fertilised and implant. It is what gives you a luteal phase of your cycle. In the event pregnancy happens the corpus luteum continues to make progesterone until there is a placenta which is functioning well enough to take over hormone manufacture to protect the pregnancy (end of the first tri or thereabouts). Corpus luteum cysts are diagnosed as "ovarian cysts" if they are 3cm across or more. They are thus VERY VERY common (because EVERY pregnancy has one, and they are usually 1-2cm across), i had one that was 10cm by 7cm and i never felt it at all, and i gave birth at home, so obviously it caused no medical complications. Mine was never re-checked because they are a normal part of PG, but the midwife i saw that day said they usually shrink away when the placenta takes over and they only re-scan in the UK if they're causing pain.

From my POV it was interesting to know DD came from my right ovary.

HTH

Bx