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The most common cysts found are the functional cysts. A functional cyst can be one of four types and are not malignant: follicular, corpus luteum, theca luteum, and polycystic ovaries.
A follicular cyst occurs when the normal follicle, or sac that matured to release an egg, does not shrink after release of the egg. These are soft, have thin membrane walls, and contain clear fluid. These can rupture, causing sudden, severe pain which gradually goes away over several days. Usually, however, they spontaneously disappear over the course of one or more menstrual cycles. They can cause changes in your periods and pelvic pain. Depending on the size of the cyst, it can just be observed or treated with birth control pills.
Corpus luteum cysts are less common, but cause more symptoms and problems. They become larger than follicular cysts, thus causing more pelvic pain. They result when bleeding occurs in the follicle after an egg is released. This type of cyst often causes a delayed period and if it ruptures, can cause bleeding into the abdomen which may neccesitate surgery.
Theca luteum cysts, the least common of the functional cycts, are often asscociated with an abnormal pregnancy. They most often occur in both ovaries, unlike the functional cycts described above. They disappear without treatment after the pregnancy is terminated.