I got a phone call last night from a good friend from college, who has just recently been diagnosed with an ovarian cyst, and had been told by her doctor not to worry too much about it and was prescribed birth-control pills to help manage the symptoms. She wanted a second opinion, and I told her what I knew about ovarian cysts (i.e. that they’re very common, usually benign, usually do not affect fertility, and usually spontaneously resolve in a few months without incident), but I did promise that I’d do some more research on the subject for her. So here you go: more than you probably ever wanted to know about ovarian cysts!
An ovarian cyst is a fluid-filled sac that forms on the ovary. The majority of ovarian cysts are benign, and are classified as either functional or organic. We’ll start with functional cysts, because they are simpler and easier to understand.
Functional cysts are fluid-filled sacs which most often form during a normal menstrual cycle—either during the follicular phase or the luteal phase. Follicular cysts are more common and are often undiagnosed because they are usually asymptomatic. During the follicular phase of the menstrual cycle, the follicle ripens while the egg matures and becomes a small, fluid-filled sac in the process. During normal ovulation, when the egg is released the sac breaks open, the fluid is released along with the egg, and the remnants of the sac are eventually re-absorbed. If for some reason the egg is not released (i.e. there is no ovulation), the ripened follicle can remain as a cyst, and may continue to grow through the next menstrual cycle. Follicular cysts can occassionally grow quite large, and the risk of torsion or rupture increases the larger the cyst becomes. However, the majority of follicular cysts usually spontaneously disappear within one to three months.
Luteal ovarian cysts, or corpus luteum cysts, occur during the second half of the menstrual cycle, after ovulation has occurred. Once the follicle has ruptured and the egg has been released, the remaining follicle sac becomes the corpus luteum, which produces progesterone and maintains the endometrial lining of the uterus. If the egg is not fertilized and pregnancy does not occur, the corpus luteum normally disappears through a process called luteolysis, which occurs with the onset of menses. In some cases, though, the corpus luteum does not disappear, and instead seals off after ovulation, fills with fluid and forms a cyst. Luteal cysts are less common than follicular cysts and usually disappear on their own within a few weeks. However, they can sometimes grow up to four inches and may cause bleeding, torsion, or pain.
If a small blood vessel ruptures inside a functional cyst, the cyst fills with blood instead of clear fluid, and is then called a hemorrhagic cyst. However, like follicular and luteal cysts, hemorrhagic cysts rarely rupture, are often self-limiting, and will most likely spontaneously resolve on their own.
Organic cysts are the second type of ovarian cyst, and are much less common than functional cysts. They’re referred to as complex cycts because of how they appear on ultrasound, and may contain blood, serous or solid material inside them. The type of cyst that forms depends on the type of ovarian tissue the cyst arises from. “Mucinous or serous cysts arise from mucinous or secretory ovarian glandular cells and can become very large, though they usually grow slowly.” (Schuiling & Likis, 2006). Another type of organic cyst known as a dermoid cyst arises from ovarian germ cells. Because germ cells have the capability of forming any material in the body, dermoid cysts sometimes contain unusual substances such as hair cells, skin cells, bone cells, tooth enamel or other body material. Dermoid cysts tend to grow rapidly and can become very large. They are rarely malignant, however, because they don’t spontaneously regress and there is some (albeit small) chance of malignancy, dermoid cysts are most often surgically removed . Another kind of organic cyst is known as a cystadenoma, which forms in the stromal tissue on the outside of the ovary, and can also grow quite large and cause a fair amount of pain.
Ovarian cysts can also be caused by other illnesses. Endometrial tissue begins to grow outside the uterus in women with endometriosis, and can sometimes attach itself to the ovary, forming an endometrioma, which is a solid cyst. Women with polycystic ovarian syndrome (PCOS) form multiple functional cysts within their ovaries from repetitive anovulatory cycles, and are often infertile. While neither of these kinds of cysts are malignant, managing these types of cysts requires dealing with the underlying etiology—either endometriosis or PCOS—and these cysts usually do not resolve on their own without assistance.
Because ovarian cysts are usually asymptomatic, many women have them without realizing that they do, and they often resolve on their own without the woman even being aware. Otherwise, the woman may experience pressure or fullness in the abdomen, pain during intercourse, persistent low-back ache, urinary frequency, chronic pelvic pain or pain during menstruation. Ovarian cysts are sometimes detected during a routine pelvic exam if a large mass or fullness is felt around the ovaries. However, diagnosis is most often made by ultrasound (either abdominal or transvaginal ultrasound), and management depends in part on the size of the cyst.
For most functional cysts, nothing needs to be done. Simple cysts don’t require therapy unless they’re larger than 8 cms, rupture or lead to ovarian torsion. The “watch and wait” approach is most often used, since these cysts usually spontaneously resolve on their own. If there is minor pain associated with the cyst, medication like Motrin or Tylenol is usually enough to manage the pain while waiting for the cyst to disappear. Follow-up ultrasounds at 1-3 months after diagnoses are sometimes performed, but aren’t mandatory unless the symptoms persist or worsen. If the cyst is between 5-8 cm, repeat visits to your doctor or midwife may be needed to follow the growth of the cyst. Surgery may be required to drain and remove larger cysts (anything greater than 8 cm), and is usually done either through laparoscopy or laparotomy. Other tests, such as a blood test to check for CA-125, a tumor marker which can indicate malignant growth, may also be performed for larger cysts just to rule out cancer. Oral contraceptive pills can be prescribed to help reduce the likelihood of repeat cyst formation, and may be especially helpful in women who keep having ovarian cysts. Since ovulation and the ripening of a follicle are often the causes of functional cyst formation, birth control prevents this from happening by preventing ovulation.
Organic cysts are generally more complex and usually require medical treatment. An MRI or cat-scan may be used in addition to ultrasound in order to diagnose the exact type of cyst (dermoid, cystadenoma, endomerioma etc.) The tumor marker CA-125 will most likely be checked to rule out cancer, and larger cysts greater than 8 cm will most likely be removed via surgery.
Warning signs for the rupture of an ovarian cyst include nausea and vomiting, fever, sudden, severe abdominal pain, fainting, dizziness, weakness or rapid breathing. In the case of very large cysts, rupture can be quite dangerous, so emergency care should be sought immediately if any of the warning signs appear. Otherwise, as in the case of my friend, who has some type of functional cyst by the sound of it, I’d agree with her doctor’s assessment that she shouldn’t worry too much about it. The cysts will probably go away on their own, and using oral contraceptives will make the likelihood of future cyst formation very, very slim.
References and further resources:
Shuiling & Likis (2006) Chapter 22: Benign Gynecologic Conditions. Women’s Gynecologic Health, pp. 584-587, Boston, MA: Jones and Bartlett.
Varney, H. et. al. (2004) Chapter 14: Common Diagnoses in Women’s Gynecological Health. Varney’s Midwifery: Fourth Edition, p. 406, Boston, MA: Jones and Bartlett.