What You Should Know About a Corpus Luteam Cyst in Pregnancy

Ultrasound technicians with pregnant woman
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During the second half of your menstrual cycle, you may have a small fluid-filled sac known as a corpus luteal cyst, or corpus luteum cyst, on your ovary. The size of this cyst may vary but it typically two to six centimeters.

A corpus luteal cyst is known as a functional cyst. This arises as a cyst of the corpus luteum, the empty follicle after ovulation. The corpus luteum releases progesterone until the placenta takes over this function around twelve weeks gestation.

How a Corpus Luteum Cyst Is Found

Some women will notice one-sided pain. This may cause them to be concerned or to worry. They may wonder if they have an ectopic or tubal pregnancy. When they talk to their doctor or midwife, a history is taken and then usually some testing is done. A corpus luteal cyst is usually diagnosed via ultrasound. Typically this involves a transvaginal ultrasound, an internal ultrasound which can give better details to what is going on inside your body.

"I had this ache on my right side," explained one mother-to-be. "It never really went away but would sometimes cause sharp pain. I was really worried that it meant that something really wrong was going on. I was so relieved that it was only a corpus luteal cyst. I could tolerate the pain knowing my baby was okay. After a few weeks, it just stopped hurting. Thankfully it never happened again in another pregnancy, but I was prepared if it did."

You are more likely to have a corpus luteal cyst if you took medication to induce ovulation, like Clomid. This is usually prescribed by your doctor or midwife. These medications are used in cases of fertility problems. So it is very likely that you would know if you had taken these types of medication. Though it is important to note that you can have these types of functional cysts even when you are not pregnant, nor when you have taken medication. 

Should I Worry About a Corpus Luteal Cyst?

A corpus luteal cyst is usually not a cause for concern nor does it usually adversely affect the pregnancy or cause miscarriage. Sometimes you may experience a bit of pain or tenderness. Your doctor or midwife may prescribe pelvic rest or pain medications. The most frequent scenario is that the cyst will resolve on its own.

Occasionally the cyst will rupture causing pain. This increased pain usually subsides fairly rapidly, but your doctor or midwife can help you treat it if need be. An even less likely event would be that the cyst could cause the ovary to twist and potentially require surgery to prevent your ovary from further injury. This is called torsion. Your doctor or midwife will explain the likely course for your situation and provide you a list of warning symptoms that would mean you would need to call or be seen. 

There is usually no follow-up needed after you have been diagnosed with a corpus luteal cyst unless you require medical treatment. Sometimes a second ultrasound may be done, but as the symptoms subside, the need for follow-up and treatment decline.

Likelihood of Corpus Luteal Cyst Recurrence

Just because you have had a corpus luteal cyst in one pregnancy does not mean that you will experience it again in another pregnancy. Even if you did have another cyst, it may or may not be painful. Many women may have them and without the experience of pain or happening to stumble across them during an ultrasound for another reason, would never have seen them. 

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Article Sources
  • Borders RJ, Breiman RS, Yeh BM et-al. Computed Tomography of Corpus Luteal Cysts. J Comput Assist Tomogr. 2004;28 (3): 340-2.
  • Obstetrics: Normal and Problem Pregnancies. Gabbe, S, Niebyl, J, Simpson, JL. Sixth Edition.
  • Ovarian Cysts. The American College of Obstetricians and Gynecologists. 
  • Ovarian Cysts Fact Sheet. Office on Women's Health, U.S. Department of Health and Human Services.