Ovarian Cysts: What They Are, When to Worry, and When to Reassure Yourself

Being told you have an ovarian cyst can feel alarming, but in the vast majority of cases, there is no cause for concern. Ovarian cysts are extremely common — most women of reproductive age will develop at least one during their lifetime, often without ever knowing it. Understanding what they are, how they behave, and when they genuinely require attention can save a great deal of unnecessary anxiety.

What are ovarian cysts?

An ovarian cyst is simply a fluid-filled sac that develops on or within an ovary. The most common type, known as a functional cyst, forms as a normal part of the menstrual cycle. Each month, an egg develops inside a small follicle on the ovary. At ovulation, the follicle ruptures to release the egg. Occasionally, this process does not go entirely to plan, and a cyst forms instead. These functional cysts are not a sign of disease — they are a byproduct of healthy ovarian activity.

Types of ovarian cysts

While functional cysts are by far the most common, there are several other types that a gynaecologist may encounter:

• Follicular cysts: These occur when the follicle does not rupture at ovulation and continues to grow. They are usually small and resolve within one to three cycles.
• Corpus luteum cysts: After ovulation, the empty follicle normally shrinks. Sometimes it seals itself and fills with fluid, forming a corpus luteum cyst. These too are typically self-limiting.
• Dermoid cysts (teratomas): These unusual but benign cysts can contain tissue such as hair, skin, or even teeth. They develop from embryonic cells and tend to grow slowly over years.
• Endometriomas: Sometimes called chocolate cysts, these form when endometriosis tissue attaches to an ovary. They contain old blood and are associated with pelvic pain and fertility difficulties.
• Cystadenomas: These develop from the surface of the ovary and can sometimes grow quite large. They are usually benign but may require removal if they cause symptoms or continue to enlarge.

Symptoms: often none at all

Most ovarian cysts cause no symptoms whatsoever and are discovered incidentally during a routine ultrasound or examination. When symptoms do occur, they may include:

• A dull ache or heaviness in the lower abdomen or pelvis
• Bloating or a feeling of fullness
• Pain during sexual intercourse
• Changes in menstrual pattern
• A need to urinate more frequently if the cyst is pressing on the bladder

When to worry

While most cysts are harmless, certain situations do warrant prompt medical attention:

• Sudden, severe pelvic pain: This may indicate that a cyst has ruptured or that the ovary has twisted on itself (ovarian torsion), both of which require urgent assessment.
• Large cysts: Cysts measuring more than 5 centimetres are more likely to cause symptoms and have a slightly higher risk of complications.
• Complex appearance on ultrasound: Cysts with solid components, internal septations, or irregular walls need further evaluation to exclude the rare possibility of malignancy.
• Cysts found after the menopause: Because ovulation has ceased, new cysts in postmenopausal women are not functional and may require closer investigation.

How are ovarian cysts investigated?

The cornerstone of assessment is a transvaginal ultrasound, which provides detailed images of the ovaries and any cysts present. An experienced sonographer or gynaecologist can often determine the type and nature of a cyst from its appearance alone. In some cases, a blood test for the tumour marker CA125 may be requested, particularly in postmenopausal women or when the ultrasound findings are not entirely straightforward. It is worth noting that CA125 can be raised by many benign conditions, including endometriosis, fibroids, and even menstruation, so it must always be interpreted in context.

Management: from reassurance to surgery

The approach to managing an ovarian cyst depends entirely on its type, size, appearance, and whether it is causing symptoms. For the majority of simple functional cysts, watchful waiting is all that is required — a follow-up ultrasound after two to three cycles will usually confirm that the cyst has resolved on its own. Persistent cysts, those causing significant symptoms, or those with concerning features may be removed surgically. Laparoscopic (keyhole) surgery is the standard approach and typically involves a short recovery period. In most cases, the ovary itself can be preserved.