Ovarian Cysts: Types, Causes & When to Take Action

What Are Ovarian Cysts?

An ovarian cyst is a fluid-filled sac that develops on or within an ovary. They are extraordinarily common — most women will develop at least one during their lifetime, and many will form cysts regularly as a normal part of their menstrual cycle without ever knowing it. The vast majority are benign, cause no symptoms, and resolve spontaneously within a few weeks to months.

That said, "common" doesn't mean "unimportant." Ovarian cysts are often a signal worth paying attention to. They can reflect underlying hormonal imbalances, disrupted ovulation, elevated oestrogen, or conditions like PCOS or endometriosis. Understanding what kind of cyst you have — and why it formed — gives you genuinely useful information about what's happening inside your body.

The fear and confusion that often accompanies an ovarian cyst diagnosis is understandable, especially when the information you receive is minimal. My aim here is to give you a clear, grounded understanding so you can make sense of what you're dealing with and take informed action.

Functional vs. Pathological Cysts

The most important distinction in understanding ovarian cysts is between functional cysts — which are a normal byproduct of the menstrual cycle — and pathological cysts, which arise from abnormal cell growth and are less common but require closer attention.

Functional cysts include two main types. Follicular cysts form when a follicle (the fluid-filled sac that houses a developing egg) fails to rupture at ovulation and continues to grow. They are the most common type, typically resolve on their own within one to three menstrual cycles, and are rarely symptomatic. Corpus luteum cysts form after a follicle successfully releases its egg; the resulting corpus luteum (which normally produces progesterone in the second half of the cycle) fills with fluid instead of breaking down. These can sometimes be tender, particularly during the luteal phase, and may cause a delayed period.

Pathological cysts include several types that deserve more careful monitoring:

• Dermoid cysts (teratomas) contain tissue such as hair, skin, or teeth and are thought to arise from embryonic cells. They are almost always benign but can grow large and sometimes require surgical removal.
• Cystadenomas develop from cells on the ovarian surface and can be filled with either watery fluid or mucous material. They tend to grow larger than functional cysts.
• Endometriomas — sometimes called "chocolate cysts" — are filled with old menstrual blood and develop as a consequence of endometriosis. They can impair ovarian reserve and fertility and generally do not resolve without treatment.

It's also worth clarifying what PCOS-related "cysts" are — because despite the name, they are not true cysts. The small follicles visible on the ovaries in PCOS are immature, arrested follicles that have failed to ovulate, not fluid-filled sacs in the classical sense. PCOS is a hormonal condition that requires its own distinct conversation.

Symptoms

Many ovarian cysts produce no symptoms at all and are discovered only during a routine pelvic ultrasound. When symptoms do occur, they may include:

• Dull aching or sharp pain on one side of the lower abdomen or pelvis
• A feeling of fullness, heaviness, or bloating in the lower belly
• Pain during sex, particularly with deep penetration
• Changes to the menstrual cycle, including irregular bleeding or a delayed period
• Increased urinary urgency if a cyst is pressing on the bladder

Sudden, severe, one-sided pelvic pain — especially if accompanied by nausea, vomiting, fever, or faintness — can indicate a cyst has ruptured or that ovarian torsion (twisting of the ovary on its ligaments) has occurred. Both are medical emergencies requiring immediate attention.

What Causes Cysts to Form

For functional cysts, disrupted ovulation is the primary driver. When ovulation is irregular or anovulatory cycles occur — meaning a cycle passes without an egg being released — the follicle may not rupture as it should, leading to cyst formation. This is why conditions that disrupt ovulation also tend to be associated with recurrent cysts.

Hormonal imbalances play a significant role. Elevated oestrogen relative to progesterone can drive follicular development without triggering the LH surge needed for ovulation. High prolactin levels, thyroid dysfunction, elevated androgens, and HPA axis dysregulation (the stress hormone system) can all interfere with the precise hormonal choreography of the cycle and increase the likelihood of cyst formation.

Insulin resistance is another meaningful contributor. High insulin stimulates the ovaries to produce androgens and can suppress the mid-cycle LH surge, preventing ovulation. This is a key reason why women with PCOS — who often have significant insulin resistance — are prone to multiple arrested follicles.

Inflammation and oxidative stress are increasingly recognized as contributing factors in cyst formation and persistence. The ovarian environment is sensitive to systemic inflammation, and a diet and lifestyle that perpetuate a chronic low-grade inflammatory state can impair normal follicular dynamics.

When to See a Doctor

Not every ovarian cyst needs treatment — but every cyst does deserve appropriate monitoring. The following situations warrant prompt medical evaluation:

• Sudden, severe, or worsening pelvic pain — seek emergency care immediately if accompanied by vomiting, fever, or dizziness
• A cyst that persists beyond two to three menstrual cycles on repeat ultrasound
• A cyst that is growing rather than shrinking
• A cyst with complex features on ultrasound, such as solid components, septations, or increased vascularity
• Cysts occurring after menopause, which warrant closer investigation
• Symptoms that are significantly disrupting your quality of life

A transvaginal ultrasound is the gold standard for assessing ovarian cysts. In some cases, an MRI may provide additional detail. Blood tests including CA-125 may be ordered — though it's worth knowing that CA-125 is not specific to ovarian cancer and can be elevated in many benign conditions including endometriosis and fibroids. A single elevated result should not be a cause for panic, but rather prompt thoughtful follow-up.

Supporting Hormonal Balance

For women dealing with recurrent functional cysts, the most productive approach is to address the hormonal disruption that's preventing regular ovulation. This typically involves a combination of the following:

• Balance blood sugar to reduce insulin-driven disruption to ovulation: prioritise protein and healthy fats at meals, reduce refined carbohydrates, and avoid long gaps between eating
• Support liver and gut function for healthy oestrogen clearance — cruciferous vegetables, fibre, and minimising alcohol are the foundations
• Address chronic stress, which suppresses the HPG (hypothalamic-pituitary-gonadal) axis and can delay or prevent ovulation
• Ensure adequate micronutrient status, particularly zinc, magnesium, vitamin D, and B6, all of which support healthy ovarian function and progesterone production
• Track your cycle — basal body temperature charting or LH monitoring can help confirm whether ovulation is occurring and when
• Consider castor oil packs over the lower abdomen, a traditional practice with some evidence suggesting benefits for pelvic circulation and lymphatic drainage, which may support cyst resolution

Ovarian cysts can feel alarming when you first hear about them — but most of the time, they are a solvable and informative part of your hormonal story. The goal is always to understand what your body is signalling rather than to silence it.

This article is for educational purposes only and does not constitute medical advice. Always consult a qualified healthcare provider for diagnosis and treatment of any health condition.