Hiya Linny
Glad your scan went well today and baby is well.
A Corpus luteum cyst develops in the second half of the cycle after the egg has been released. As soon as ovulation has taken place in a normal cycle, the ruptured follicle then develops into the corpus luteum which produces progesterone in anticipation of a pregnancy.
A luteal cyst is formed when the corpus luteum fails to wither when it should, and fills with blood instead.
A typical corpus luteum is round and fluid-filled and can range in size from less than 2cm to 6cm or more. On ultrasound, a fluid-filled structure greater than three centimeters is technically classified as an ovarian cyst, even though it may well represent a normal finding.
Corpus luteum cysts appear toward the end of the menstrual cycle, last into early pregnancy, and then usually resolve over a period of time without any special treatment.
Your cyst is proberbly being monitored because occasionally a cyst will rupture,which can be quite painful, but not dangerous to you or the baby.
Also cyst can in rare instances cause the ovary to twist, cutting off its blood supply and resulting in pain and nausea. This would require surgery.
But please don't worry - Corpus luteum cysts usually resolve painlessly by the beginning of the second trimester.
Hope this hepls
they told me i have a 6cm corpus luteal cyst on the right side though. has anyone heard of this? 
They are going to measure it again at my 12 week scan.
