Corpus Luteum Cysts During Pregnancy

What Is a Corpus Luteum Cyst?

A corpus luteum cyst is a type of ovarian cyst (a small fluid-filled sac) that can happen during pregnancy. The condition, which is also called a corpus luteal cyst, can occur when you're not pregnant, primarily during the reproductive years. Understanding the ovulation process can help to explain how and why these cysts develop.

During the second half of the menstrual cycle, immediately following ovulation, the empty ovarian follicle forms the corpus luteum. The corpus luteum releases estrogen as well as progesterone, which readies the uterus for implantation. If conception has occurred, 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 luteal cysts are a type of functional cyst. While they vary in size, corpus luteal cysts are usually between 2 and 6 centimeters. Though they are usually not a cause for concern, these cysts can lead to complications, though not typically related to pregnancy itself. Having had a corpus luteal 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

The most common symptom is a slight twinge of one-sided pain or mild tenderness during your 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.

But in many cases, women who have a corpus luteal cyst do not experience any pain and may not even realize they have developed one. A corpus luteal cyst will typically resolve on its own after a few menstrual cycles, and most women won't even realize it was ever there.

Identifying Corpus Luteum Cysts

Corpus luteal cysts are typically diagnosed with an ultrasound. However, it may be a different type of ultrasound from the one most women expect. Cysts tend to be easier to see when an internal ultrasound (also called a transvaginal—inside the vagina—ultrasound) is used.

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.

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.

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.