An ovarian cyst is a sac, usually filled with fluid, that develops in or on an ovary. Ovarian cysts are common, particularly during the years when a person is having menstrual periods. Many cause no symptoms and disappear on their own without treatment.
Most ovarian cysts are benign. Some form as part of the normal menstrual cycle, while others develop for different reasons and may require closer evaluation.
How Ovarian Cysts Form
Many ovarian cysts develop as part of the normal menstrual cycle. Each month, a follicle grows on an ovary as an egg develops.
Normally, the follicle opens and releases the egg during ovulation. Sometimes the follicle does not release the egg or does not shrink normally afterward. Fluid can then collect inside it and form a functional ovarian cyst.
Types of Ovarian Cysts
Ovarian cysts are not all the same. Some are related to the menstrual cycle, while others develop independently of ovulation.
Functional Ovarian Cysts
Functional cysts are the most common type of ovarian cyst. They develop as part of the normal menstrual cycle and often disappear on their own.
There are two main types of functional cysts:
Follicular Cysts
A follicular cyst can develop when a follicle does not rupture and release an egg during ovulation. Instead, the follicle continues to grow and fills with fluid.
These cysts are usually harmless and often resolve without treatment.
Corpus Luteum Cysts
After a follicle releases an egg, it normally changes into a structure called the corpus luteum.
Sometimes the opening where the egg was released becomes sealed and fluid collects inside. This can form a corpus luteum cyst.
Like follicular cysts, corpus luteum cysts frequently disappear on their own.
Dermoid Cysts
Dermoid cysts, also called teratomas, develop from reproductive cells in the ovary.
Because these cells can develop into different types of tissue, a dermoid cyst may contain material such as skin, hair, or other tissue.
Dermoid cysts are usually benign, but some can grow large enough to cause symptoms or complications.
Cystadenomas
Cystadenomas develop from cells on the surface of an ovary.
They may contain watery or mucus-like material and can sometimes grow quite large. Larger cystadenomas may cause pressure, discomfort, or increase the risk of ovarian torsion.
Endometriomas
Endometriomas are ovarian cysts associated with endometriosis.
Endometriosis occurs when tissue similar to the lining of the uterus grows outside the uterus. When this tissue involves an ovary, it can form an endometrioma.
Simple and Complex Ovarian Cysts
Ovarian cysts may also be described according to how they appear on an ultrasound.
A simple ovarian cyst is generally filled with fluid and has a relatively uncomplicated appearance.
A complex ovarian cyst may contain solid areas, internal divisions, blood, or other material. A complex appearance does not automatically mean that a cyst is cancerous, but it may require additional evaluation depending on its size, appearance, symptoms, age, and other factors.
You can learn more about complex ovarian cysts, their causes, and how they are evaluated.
Are Ovarian Cysts Dangerous?
Most ovarian cysts do not cause serious problems and many disappear without treatment.
However, some cysts can become large, rupture, bleed, or cause the ovary to twist. Twisting of the ovary is known as ovarian torsion and can interfere with blood flow to the ovary.
Rarely, an ovarian mass may be cancerous. The likelihood of malignancy is higher after menopause and when imaging shows concerning features.
Possible Symptoms
Many ovarian cysts cause no symptoms.
When symptoms occur, they may include:
- pelvic pain or pressure
- abdominal fullness or bloating
- swelling in the abdomen
- discomfort during intercourse
- pain during bowel movements
Symptoms can vary depending on the type, size, and location of the cyst.
When to Seek Urgent Medical Care
Seek prompt medical evaluation for:
- sudden severe abdominal or pelvic pain
- severe pain accompanied by fever or vomiting
- dizziness or weakness
- rapid breathing
- other symptoms suggesting significant internal bleeding or shock
These symptoms can occur with complications such as ovarian torsion or a ruptured cyst.
How Ovarian Cysts Are Found
An ovarian cyst may be discovered during a pelvic examination or during imaging performed for another reason.
Pelvic ultrasound is commonly used to evaluate an ovarian cyst. Ultrasound can help determine:
- the location of the cyst
- its size
- whether it is filled with fluid
- whether it contains solid areas
- whether its appearance changes over time
Depending on the findings, a healthcare professional may recommend monitoring, additional testing, or treatment.
Ovarian Cysts and PCOS
Polycystic ovary syndrome, or PCOS, is a hormone-related condition and is not the same thing as having an ordinary functional ovarian cyst.
Functional cysts develop during the menstrual cycle. PCOS involves a broader pattern of hormonal and ovarian changes and requires a different approach to diagnosis and management.
What Happens After an Ovarian Cyst Is Found?
Many ovarian cysts can be monitored because they disappear on their own.
A healthcare professional may recommend follow-up ultrasound imaging to determine whether a cyst has disappeared, remained stable, increased in size, or changed in appearance.
Treatment decisions may depend on:
- the type of cyst
- its size
- symptoms
- ultrasound findings
- whether the cyst persists or grows
- age
- menopausal status
You can learn more about ovarian cyst treatment options and ovarian cyst treatment and management.
Medical Sources
MedlinePlus — Ovarian Cysts
MedlinePlus Medical Encyclopedia — Ovarian Cysts
Mayo Clinic — Ovarian Cysts: Symptoms and Causes
Mayo Clinic — Ovarian Cysts: Diagnosis and Treatment
Medical disclaimer: This website provides general educational information and is not a substitute for professional medical advice, diagnosis, or treatment. Contact a qualified healthcare professional with questions about symptoms, diagnosis, or treatment. Seek urgent medical care for severe or rapidly worsening symptoms.
This page is for general education and cannot diagnose a condition or replace care from a qualified healthcare professional.