Ovarian cysts: most disappear on their own, and the ovary is worth fighting for

Most cysts are the ovary doing its job

Every month the ovary grows a fluid-filled follicle that releases an egg, then forms a structure called a corpus luteum. Both are cysts in the literal sense. If a follicle does not release its egg, or the corpus luteum fills with fluid, you get a functional cyst. These are the commonest ovarian cysts by a wide margin in women who still have periods, and they usually disappear within one to three cycles without any treatment.

This creates a specific trap. An ultrasound done at the wrong point in your cycle will find a cyst that is simply a normal follicle, and a woman can be told she has an ovarian cyst that must be removed when what she has is a working ovary. The correct response to an incidentally found simple cyst in a premenopausal woman is usually a repeat scan after a few cycles, ideally timed just after a period when the ovary is quietest. Very often the second scan is clear.

So the first two questions are: when in my cycle was the scan done, and can we repeat it after my next period? A recommendation for surgery on the basis of a single scan taken mid-cycle is worth questioning.

Simple means specific things on ultrasound: thin-walled, filled with clear fluid, no solid parts, no internal blood flow, no thick divisions inside. The word appears in the report. Guidance recommends no follow-up imaging at all for small simple cysts in premenopausal women, follow-up for larger ones, with cysts of roughly 5 to 7cm followed by yearly ultrasound and those above about 7cm warranting further imaging or surgical assessment because they become harder to characterise fully by ultrasound alone.

Ask for the actual words in the ultrasound report. Simple, anechoic and unilocular are reassuring. Solid components, papillary projections, thick septations, internal vascularity and ascites are the words that change the plan.

Torsion: the emergency that must not be missed

A cyst can make the ovary heavy enough to twist on its own blood supply. When that happens the blood flow is cut off and the ovary begins to die. This is ovarian torsion, and it is one of the genuine gynaecological emergencies.

The picture is sudden, severe, usually one-sided pelvic or lower abdominal pain, very often with nausea and vomiting, sometimes coming in waves and sometimes constant. It can happen after exercise or sudden movement, and it happens in pregnancy too. It occurs in children and teenagers as well as adults, and in young girls it is regularly misdiagnosed as gastroenteritis or appendicitis.

Why the time matters: prompt surgery to untwist the ovary can save it. Delay means the ovary is dead by the time anyone operates, and it has to be removed. This is the one situation on this page where being cautious about surgery causes the harm.

One thing to know so you are not falsely reassured: ultrasound with Doppler can still show blood flow in a twisted ovary, because the blood supply comes from two directions. A normal Doppler does not rule out torsion. If the clinical picture fits, the diagnosis is made by looking, and being taken to theatre for suspected torsion that turns out to be something else is a reasonable outcome, not a mistake.

The other acute event is rupture. A cyst can burst, causing sudden pain that often eases over hours and needs only pain relief. Occasionally it bleeds significantly, and then the signs are feeling faint, a racing heart, and worsening pain with abdominal swelling. That needs emergency care.

And the diagnosis that must always be excluded in a woman of reproductive age with one-sided pelvic pain: ectopic pregnancy. A pregnancy test is not optional in this situation. If nobody has done one, ask for it.

The types that behave differently

An endometrioma, often called a chocolate cyst, is a cyst of endometriosis containing old blood. It causes painful periods, pain during sex, and can affect fertility. It does not disappear on its own. But surgery is not automatic either, because removing an endometrioma removes some healthy ovarian tissue with it and can reduce ovarian reserve, which matters greatly for a woman who wants to conceive. Hormonal treatment to suppress it is a legitimate alternative for pain. If you have an endometrioma and want a pregnancy, the trade-off between pain relief and ovarian reserve deserves a full conversation, ideally including a discussion about whether fertility preservation should be considered before surgery.

A dermoid cyst, or mature teratoma, contains a mixture of tissue types and can include hair, fat and even teeth, which sounds alarming and is benign. It does not resolve on its own, tends to grow slowly, and carries a higher risk of torsion because of its weight. Removal is usually advised, and the key point is that the cyst can almost always be removed while keeping the ovary. Removing an entire ovary for a benign dermoid in a young woman is rarely necessary.

A cystadenoma is a benign tumour of the ovarian surface that can grow large. It does not resolve and is generally removed, again with the ovary preserved where possible.

Polycystic ovaries are a source of enormous confusion. The many small follicles seen around the edge of the ovary in polycystic ovary syndrome are not cysts to be removed, and PCOS is not treated with surgery to drain them. It is a hormonal and metabolic condition managed with weight and lifestyle measures, medicines for periods and ovulation, and treatment for insulin resistance. If you have been told you need surgery to remove multiple cysts in PCOS, get another opinion. Ovarian drilling exists as a specific fertility treatment in selected cases, and that is a different, deliberate decision made in a fertility context.

A cyst in a woman after menopause is a different situation altogether, because functional cysts should not be forming when you no longer ovulate. Simple small cysts after menopause are still usually benign, but the threshold for proper assessment is much lower, and this is where CA-125, sometimes further imaging, and specialist referral belong.

The cancer question, handled honestly

Ovarian cancer is the reason this subject creates so much fear, and fear is easily converted into unnecessary surgery in one direction or false reassurance in the other. Both cause harm.

The features that raise genuine concern on ultrasound are solid components, blood flow within solid parts, papillary projections, thick irregular divisions, involvement of both ovaries, and free fluid in the abdomen. The clinical features that matter are persistent bloating, feeling full quickly, appetite loss, unexplained weight loss, and a change in bowel or bladder habit that persists for weeks. Age matters, and so does a family history of ovarian, breast, bowel or uterine cancer.

CA-125 is widely misused. It is a blood test that is often raised by things that are not cancer, including endometriosis, fibroids, pelvic infection, pregnancy, liver disease and even normal menstruation. A mildly raised CA-125 in a young woman with a simple cyst frequently means nothing, and it causes a great deal of unnecessary terror. It is much more useful in women past menopause and as part of a scoring system combined with ultrasound features and menopausal status. Ask what your result means in the context of your age and your scan, rather than treating the number alone as a verdict.

There is one point where the concern about over-surgery reverses entirely. If a cyst has genuinely worrying features, the right thing is assessment by someone who manages ovarian cancer, and surgery planned properly with the ability to stage it. A suspicious mass removed piecemeal during a routine keyhole procedure, without proper planning, can worsen the outcome. So for a suspicious cyst, the correct advice is not to avoid surgery but to make sure the right surgery is done by the right team in the right place.

Tissue removed must always be sent for histopathology. Ask for the report and keep it.

Keeping the ovary

This is the part of the conversation most often lost, and it matters for the rest of your life.

Cystectomy means removing the cyst and leaving the ovary. Oophorectomy means removing the whole ovary. For a benign cyst in a woman who has not reached menopause, cystectomy should be the default and the ovary should be preserved wherever technically possible. Ovaries are not spare parts. They produce hormones that protect bone and cardiovascular health, and losing both before natural menopause has consequences beyond fertility.

So ask before surgery: are you planning to remove the cyst or the whole ovary, and under what circumstances would that change? Get the agreed answer written on the consent form. A common and distressing report is a woman learning after the operation that an ovary was removed when she believed only the cyst was being taken.

If you have already lost one ovary, say so loudly and repeatedly. Preserving the remaining one becomes far more important, and this fact needs to be on the front of your notes rather than buried in your history.

Where fertility is a concern, particularly with endometriomas or where both ovaries are affected, ask whether your ovarian reserve should be tested before surgery, and whether egg freezing should be discussed first. That conversation has to happen before the operation, because afterwards is too late.

There are legitimate reasons to remove an ovary: a dead ovary after prolonged torsion, a cyst that cannot be separated from the ovary, suspicion of cancer, or a woman past menopause where preservation offers less benefit. Each of those is a reason that can be stated. Convenience and speed are not.

Cysts in pregnancy and in girls

Cysts found during pregnancy are common and most are corpus luteum cysts that resolve by the second trimester. Surgery in pregnancy is generally avoided unless there is torsion, rupture with bleeding, or genuine suspicion of cancer. Most cysts in pregnancy are watched with ultrasound. If surgery is genuinely needed, the second trimester is usually the safest window. Be cautious of advice to remove a simple cyst during pregnancy or, more commonly, to remove one opportunistically during a caesarean without prior discussion.

In girls and adolescents, cysts do occur and torsion is a particular risk because a cyst in a young ovary can twist easily. Two things matter here. First, a girl with sudden severe one-sided abdominal pain and vomiting needs torsion actively considered, not just gastroenteritis or appendicitis. Second, ovarian preservation in a child or teenager is critical, and even an ovary that looks black and dead after untwisting can recover function, so removal should not be automatic.

A cyst in a girl before puberty is uncommon and always warrants specialist assessment.

For any child or adolescent facing ovarian surgery, it is entirely reasonable to ask to be treated somewhere with paediatric or adolescent gynaecology experience, and to ask specifically what will be done to preserve the ovary.