Corpus Luteum Cysts During Pregnancy

Ultrasound technicians examining pregnant woman

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What Is a Corpus Luteum Cyst?

A corpus luteum cyst is a type of ovarian cyst (a small, fluid-filled sac). Also called a corpus luteal cyst, it often occurs during pregnancy. These can also appear at other times, primarily during the reproductive years.

Understanding the ovulation process can help explain how and why these cysts develop.

Your ovaries have thousands of follicles, which are little pouches that hold eggs. Once a follicle releases an egg during ovulation, it forms the corpus luteum—a short-lived structure that releases estrogen and progesterone, hormones that ready the uterus for implantation.

If conception occurs, the placenta will take over the function of progesterone production at around 12 weeks gestation. Sometimes, a corpus luteum cyst can develop on the ovary during the first trimester of pregnancy.

Corpus luteam cysts vary in size but are usually between 2 and 6 centimeters. They are usually not a cause for concern. However, these cysts can lead to complications, which are typically unrelated to pregnancy itself.

Having had a corpus luteam cyst in one pregnancy does not necessarily mean you will develop one in another pregnancy. If you do develop cysts in subsequent pregnancies, they may or may not cause pain.

Symptoms

In many cases, women who have a corpus luteal cyst do not experience any pain. In fact, a corpus luteal cyst will typically resolve on its own after a few menstrual cycles without a woman even knowing it was there.

The most common symptom in those who do take notice of a corpus luteam cyst is a slight twinge of one-sided pain or mild tenderness during the menstrual cycle. The pain may be worrisome, especially if you are sexually active and concerned about the possibility of an ectopic or tubal pregnancy. This concern may prompt a visit to a doctor or midwife.

When to Seek Emergency Care

Large corpus luteum cysts have the potential to burst and cause internal bleeding. They can also lead to ovarian torsion, a rare but serious complication in which the ovary twists around surrounding tissues.

Immediate medical attention is needed if any symptoms of these conditions arise, including:

  • Sudden, sharp, one-sided pain in the lower abdomen or pelvis
  • Shoulder pain
  • Fainting or dizziness

Identifying Corpus Luteum Cysts

Corpus luteal cysts are typically diagnosed with a transvaginal ultrasound, also called an internal ultrasound.

Your provider inserts a wand called a transducer into your vagina. The device emits sound waves that produce images of the inside of your body and projects them on to a monitor.

While an ultrasound may be ordered if you have symptoms, cysts are often found during a routine ultrasound for other purposes, both in women who are pregnant and those who are not.

There may be more opportunities to spot a corpus luteal cyst in a woman who's expecting, simply because they're usually having routine imaging as part of their prenatal care.

So, these cysts may be diagnosed more often during pregnancy.

Your doctor or midwife may want you to have a follow-up ultrasound to check on the cyst if you continue to have symptoms. Otherwise, unless treatment is required, no follow-up is typically needed.

Risk Factors

Anyone can get corpus luteal cysts, though they are more likely to develop in women taking medication to induce ovulation, like Clomid (clomiphene). These medications are usually prescribed by a doctor or midwife for women experiencing fertility problems and for those with polycystic ovary syndrome (PCOS).

It's important to remember that since the corpus luteum is a normal part of the menstrual cycle, the type of functional ovarian cyst associated with them can also develop when you are not pregnant. You can also develop one even if you are not taking, or have never taken, medication to treat infertility.

Treatment

A corpus luteal cyst is usually not harmful. The cysts do not typically cause any complications during pregnancy, especially when they're discovered during the first trimester. If the cyst is potentially malignant, meaning it could grow or worsen, surgery may be required to avoid the risk of miscarriage.

If the cyst is causing pain, your doctor or midwife may prescribe pelvic rest (no sexual activity) or pain medications. However, in most cases, a corpus luteal cyst will resolve on its own without intervention.

Occasionally, the cyst will rupture. Pain may increase when this happens but subside quickly, and pain medication and rest may be indicated. Less frequently, a corpus luteal cyst can cause the ovary to twist (torsion). This can be very painful and may require surgery to prevent further injury of the ovary.

Can a Corpus Luteum Cyst Be Cancerous?

No. These cysts are what are called functional cysts—sacs that form on the ovary simply due to the normal process of menstruation. Unlike some other ovarian cysts, these do not have the potential to become cancerous.

A Word From Verywell

While it may feel unsettling to learn you have an ovarian cyst, corpus luteum cysts usually do not cause pain or complicate pregnancy or birth. Also, they rarely require any treatment. 

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