Can Ovarian Cysts Be Cancerous, Cause Bleeding or Affect Fertility?

The phone call usually comes a day or two after a routine scan. A technician saw something on the left ovary, the message says, and the doctor would like to talk. By the time the appointment arrives, a two-centimeter fluid pocket has grown, in the imagination, into something far larger.

That gap between what a cyst is and what it feels like to hear about one is worth closing. Ovaries are busy organs. Every month, in someone who ovulates, they build a fluid-filled follicle roughly the size of a blueberry, release an egg, and then remodel what is left behind. When that process stalls, a cyst is what remains. It happens so often that many people carry one without ever knowing.

Still, three questions come up again and again in the clinic, and they deserve straight answers rather than reassurance alone: could this be cancer, is this why I am bleeding, and will it affect my chances of having a baby?

Can ovarian cysts be cancerous?

Yes, but rarely, and the word rarely carries real weight here. The NHS describes ovarian cysts as very common and states plainly that most are non-cancerous. The Mayo Clinic makes the same point from the other direction: the majority present little or no discomfort and go away without treatment within a few months.

Why, then, does the question feel so urgent? Partly because ovarian cancer has a reputation for being found late, and partly because a cyst and an early tumor can look similar in a single sentence on a scan report. Both are growths on the ovary. Both can contain fluid. The difference lies in what the wall of that growth is made of and how the cells inside are behaving.

A functional cyst is essentially a follicle or a corpus luteum, the structure that produces progesterone after ovulation, that kept filling with fluid instead of shrinking. Its lining is made of ordinary ovarian cells doing an ordinary job. A cancer, by contrast, is a population of abnormal cells that keeps dividing and, over time, forms solid tissue, invades neighboring structures, and can spread.

So the honest answer has two halves. The first is that the odds are strongly in your favor, especially before menopause. The second is that a small number of cysts do turn out to be cancerous or borderline, which is exactly why clinicians follow certain features rather than dismissing every cyst on sight. The rest of this article explains what those features are.

Why most cysts are just the ovary doing its job

Consider the monthly routine. Early in the cycle, several follicles begin to grow; one becomes dominant and reaches about two centimeters before releasing its egg. The emptied follicle then folds in on itself and becomes the corpus luteum, a small hormone factory that lasts roughly two weeks before dissolving if pregnancy does not occur.

Two things can go wrong with this choreography, and both produce what MedlinePlus and the Mayo Clinic call functional cysts:

• Follicular cyst: the follicle never ruptures to release its egg and keeps accumulating fluid, sometimes reaching the size of a walnut or larger.
• Corpus luteum cyst: the follicle does release its egg, but the opening seals over and fluid or blood collects inside.

Neither of these is a disease in the usual sense. They are a normal process that overshot. According to the Mayo Clinic, they typically shrink and vanish within two or three menstrual cycles, which is why the standard response to a simple cyst in someone who is still having periods is a repeat scan rather than a procedure.

A useful mental picture: the ovary is more like a construction site than a museum. Structures are built and dismantled constantly. A cyst is often just scaffolding that stayed up a few weeks longer than planned. That framing matters because the emotional weight of the word cyst rarely matches what is actually happening in the tissue.

Which types of ovarian cyst are more likely to raise concern?

Not every cyst is functional. A second group, sometimes called pathological cysts, arises from abnormal cell growth rather than the menstrual cycle. The NHS and Cleveland Clinic describe the main types, and knowing them helps decode a scan report.

• Dermoid cysts (teratomas): form from cells that were present before birth and can contain hair, skin, or teeth. They sound alarming but are almost always benign. They can grow large and are prone to twisting the ovary.
• Cystadenomas: develop from the surface cells of the ovary and fill with watery or mucus-like fluid. Most are benign, though they can become very large, and their close cousins, cystadenocarcinomas, are cancerous.
• Endometriomas: often called chocolate cysts because they contain old, dark blood. They occur when endometrial-like tissue grows on the ovary as part of endometriosis.
• Borderline tumors: a category between clearly benign and clearly malignant, with abnormal cells that do not invade surrounding tissue. These usually still require surgical removal and careful follow-up.

The pattern to notice is that being non-functional does not mean being cancerous. Dermoids and most cystadenomas are benign. What these cysts share is that they will not resolve on their own, so the conversation shifts from waiting to deciding whether and when to remove them.

Polycystic ovary syndrome deserves a footnote here. Despite the name, the ovaries in PCOS contain many small immature follicles, not true cysts, and the condition is not associated with the kind of growth discussed in this section.

What are the symptoms of a cancerous ovarian cyst?

Here is the uncomfortable truth that top-ranking articles tend to soften: there is no symptom that reliably separates a cancerous cyst from a benign one. The early symptoms of ovarian cancer overlap almost entirely with those of large benign cysts, and both overlap with irritable bowel syndrome, constipation, and ordinary bloating.

Where a difference exists, it is one of pattern rather than kind. The Mayo Clinic notes that benign cysts often cause no symptoms at all, or produce a dull ache or pressure on one side that comes and goes. Cancer-related symptoms tend to be persistent and progressive. They are there most days, they slowly get worse over weeks, and they do not track with the menstrual cycle.

Features that prompt clinicians to look harder include:

• Bloating or abdominal swelling that does not settle between meals or across the month.
• Feeling full quickly or losing appetite without trying to.
• Pelvic or lower abdominal pain that is constant rather than cyclical.
• Unexplained weight loss or new fatigue alongside the pelvic symptoms.
• Symptoms beginning after menopause, when functional cysts no longer form.

None of these proves cancer. Endometriomas ache, dermoids press on the bladder, and a large cystadenoma can make the abdomen swell visibly. That is precisely why symptoms alone are never used to make the call. They are the reason to arrange a scan, and the scan is where the real information lives.

What are the first warning signs of ovarian cancer?

The NHS symptom guidance for ovarian cancer is refreshingly concrete. It lists four core symptoms and, crucially, gives a frequency threshold: see a GP if you have been experiencing them frequently, meaning more than 12 times a month.

The four are a swollen tummy or persistent bloating, pain or tenderness in the tummy or pelvis, no appetite or feeling full quickly after eating, and an urgent need to pass urine or needing to go more often. Other listed symptoms include indigestion, constipation or diarrhea, back pain, unexplained tiredness, unintended weight loss, and bleeding from the vagina after menopause.

The twelve-times-a-month figure is doing something important. Everyone bloats after a large meal. Almost everyone has an occasional day of pelvic discomfort. Ovarian cancer is suspected not when a symptom appears but when it becomes the background of daily life, present on most days for several weeks.

A frequently repeated myth is that ovarian cancer is silent. The more accurate statement, supported by the pattern in the NHS list, is that its symptoms are quiet and easily attributed to something else. Bloating gets blamed on diet. Urinary frequency gets blamed on age or coffee. Feeling full early gets welcomed as a diet success. The skill, for both patients and clinicians, is noticing when several vague symptoms cluster and persist together.

If that describes your recent weeks, a conversation with a doctor is warranted regardless of whether a cyst has ever been mentioned. Most such conversations end with reassurance, and a few end with a diagnosis made earlier than it otherwise would have been.

Can ultrasound tell the difference between ovarian cysts and cancer?

Ultrasound cannot see cancer cells, but it can see architecture, and architecture is remarkably informative. A transvaginal ultrasound, in which a slim probe is placed in the vagina to get close to the ovaries, is the first-line test recommended by the NHS and the Mayo Clinic. What the sonographer describes is what drives the next step.

Feature on ultrasound	Typically reassuring	Prompts closer evaluation
Contents	Clear fluid only (simple cyst)	Solid areas, or mixed solid and fluid
Wall	Thin, smooth	Thick, irregular, or with growths projecting inward
Internal divisions	None, or a single thin one	Multiple thick septations
Blood flow (Doppler)	Little or none within the cyst	Increased flow into solid parts
Surroundings	No free fluid in the pelvis	Fluid in the abdomen (ascites), or growths on both ovaries
Change over time	Shrinks or disappears on repeat scan	Grows or develops new solid components

A simple cyst, thin-walled and filled with clear fluid, is so consistently benign that clinicians often recommend nothing more than a follow-up scan. The picture becomes more complex when solid tissue appears, because cancers are made of cells, and cells are solid.

Two caveats keep this honest. First, benign cysts can look complex. A corpus luteum cyst filled with clotted blood, an endometrioma, and a dermoid all produce echoes that are not simple fluid. Second, some early cancers can appear deceptively bland. Ultrasound therefore sorts cysts into probability bands, not verdicts. In the UK, clinicians combine the scan findings with a blood test and menopausal status into a formal risk score, a structured approach that reflects how much ultrasound can and cannot do alone.

How do you find out if an ovarian cyst is cancerous?

The path from a suspicious scan to a definitive answer usually has three stages, and only the last one is truly conclusive.

Blood tests. The most familiar is CA-125, a protein that is often raised when ovarian cancer is present. Its limitation is well documented by the NHS: levels also rise with endometriosis, fibroids, pelvic infection, pregnancy, and even during a normal period. A raised result in a premenopausal person is therefore common and frequently unrelated to cancer, while a normal result does not rule cancer out. After menopause, when those benign causes fall away, the test becomes more informative. Other markers may be added for specific cyst types, particularly in younger patients.

Further imaging. When ultrasound leaves the question open, MRI is often the next step. It characterizes tissue more precisely, distinguishing fat in a dermoid from old blood in an endometrioma from genuinely solid tumor tissue. CT scanning is used mainly to look beyond the ovary if cancer is suspected.

Surgery and pathology. Biopsying an ovarian cyst through the skin is generally avoided because puncturing a cancerous cyst risks spreading cells into the abdomen. The definitive answer comes when the cyst, or the whole ovary, is removed and examined under a microscope. Sometimes a rapid assessment is done during the operation so the surgical team can decide how much to remove while the patient is still asleep.

It follows that anyone told a cyst is being removed to find out what it is has not been given a diagnosis of cancer. They have been given the only reliable way to exclude one.

Does menopause change how seriously a cyst is taken?

It changes almost everything about the calculation. Before menopause, the ovary generates follicles every month, so a fluid-filled cyst has an obvious, benign explanation. After menopause, follicles stop forming. A new cyst therefore has to be explained by something else, and the list of something-elses includes cancer more often than it does at thirty.

The NHS makes both points directly: ovarian cancer mainly affects women over 50, and cysts found after menopause carry a slightly higher chance of being cancerous, which is why regular monitoring with ultrasound and blood tests is recommended. The Mayo Clinic adds that cysts in this age group are less likely to resolve on their own.

This does not mean every postmenopausal cyst is treated as a threat. Small, simple, thin-walled cysts are common after menopause too, and many are followed rather than removed. What shifts is the threshold for action. A complex cyst that might earn a repeat scan in a 28-year-old is more likely to earn a referral to a gynecological oncology team in a 68-year-old, even when it looks identical.

Personal and family history sit alongside age. Having a close relative with ovarian or breast cancer, or carrying an inherited gene change such as BRCA1 or BRCA2, raises baseline risk and lowers the bar for investigation. A clinician weighing a cyst is not looking at the ovary in isolation. They are asking what this cyst means in this body, at this age, with this history.

Can ovarian cysts cause bleeding?

They can, through two quite different mechanisms, and it helps to separate them.

Hormonal bleeding. Functional cysts are made of hormone-producing tissue. A follicular cyst may keep secreting estrogen; a corpus luteum cyst may keep producing progesterone longer than the two weeks a normal one lasts. Either can nudge the uterine lining off schedule. The NHS lists heavy periods, irregular periods, or periods lighter than usual among cyst symptoms, and spotting between periods or a delayed period are common reports. This kind of bleeding tends to settle once the cyst resolves.

Bleeding from the cyst itself. A cyst can bleed into its own cavity, producing what radiologists call a hemorrhagic cyst, or it can rupture and spill fluid and blood into the pelvis. Rupture often follows exercise, intercourse, or nothing identifiable at all. The Mayo Clinic describes the classic result as sudden, severe pain on one side of the lower abdomen. Most ruptures involve small amounts of blood and settle with rest and pain relief chosen by a clinician, but a heavily bleeding rupture is a genuine emergency.

Where does cancer fit? Vaginal bleeding is not a typical early feature of ovarian cancer, with one important exception highlighted by the NHS: any bleeding after menopause needs prompt assessment. It is far more often caused by conditions of the uterine lining than by the ovary, but it is never treated as normal.

A practical distinction, then: cyclical irregularity that comes and goes is usually hormonal and benign; sudden pain with bleeding suggests rupture; bleeding after menopause always warrants a visit.

Do ovarian cysts affect fertility?

The reassuring answer covers most people: functional cysts do not damage fertility. They are, after all, a byproduct of ovulation. Dermoid cysts and cystadenomas also do not typically interfere with the ovary’s ability to release eggs unless they become very large or twist the ovary. The Mayo Clinic makes this point explicitly, noting that most cysts do not affect a person’s ability to become pregnant.

The exceptions are worth knowing, because they are the ones people actually worry about.

• Endometriomas. These are a marker of endometriosis, a condition that can distort pelvic anatomy, cause inflammation, and reduce the ovarian reserve. The cyst itself and the disease around it both matter. Surgery to remove an endometrioma can relieve pain but also removes some healthy ovarian tissue, so the decision is weighed carefully in anyone planning a pregnancy.
• Polycystic ovary syndrome. The many small follicles seen on scan are not the problem in themselves; the hormonal imbalance that stops them maturing is. PCOS is a common cause of irregular or absent ovulation, and it is managed as a hormonal condition rather than a cyst.
• Surgery itself. Any operation on an ovary carries a small risk to its blood supply and egg-containing tissue. Removing a whole ovary halves the supply of eggs, though the remaining ovary usually continues to ovulate normally.

Anyone with a cyst who is planning a pregnancy, now or later, should say so before any treatment is decided. It changes the conversation about whether to wait, whether to operate, and how conservative the surgery should be. Fertility considerations are a legitimate reason to choose one path over another, and the treating team expects to hear them.

What happens when a cyst ruptures or twists the ovary?

Two complications turn a quiet cyst into an urgent one, and both announce themselves with pain that is hard to ignore.

Rupture. Thin-walled cysts can burst under pressure. Most ruptures release a small amount of fluid, cause sharp one-sided pain for a few hours to a couple of days, and then settle as the fluid is reabsorbed. A hemorrhagic rupture is different: ongoing bleeding into the abdomen can cause pain that spreads, lightheadedness, a racing heart, and shoulder-tip pain from blood irritating the diaphragm. That combination needs emergency assessment.

Torsion. A cyst adds weight to the ovary, and a heavy ovary can twist on the ligament that carries its blood supply, much as a fruit can twist on its stem. The Mayo Clinic and Cleveland Clinic both flag this as the reason larger cysts, and dermoids in particular, are often removed even when benign. Torsion causes sudden severe pain, frequently with nausea and vomiting, and it is a surgical emergency because a twisted ovary loses its blood supply within hours.

Red-flag signs that warrant same-day care: sudden severe pelvic or abdominal pain; pain accompanied by fever or vomiting; feeling faint, cold, clammy, or breathing rapidly; or pain that keeps escalating rather than easing. These signs point to rupture with bleeding, torsion, or infection, none of which should wait for a routine appointment. Calling emergency services or going to an emergency department is the right response.

The vast majority of cysts never do either of these things. Knowing what they feel like simply means you will not hesitate if one does.

What does watchful waiting actually involve, and how long does it take?

Being told to wait can feel like being told nothing is happening. In fact, watchful waiting is an active strategy with a specific logic: functional cysts have a natural lifespan, and time is the cheapest and safest diagnostic test available.

The Mayo Clinic describes the typical approach for a small, fluid-filled cyst in someone who is still menstruating. No treatment is given; instead, a repeat ultrasound is arranged to confirm the cyst has shrunk or gone. The NHS frames the timing as a follow-up scan a few weeks or months later, often timed to a different point in the menstrual cycle so that a new follicle is not mistaken for the old cyst. The Mayo Clinic notes that most such cysts disappear within a few months.

What the interval scan shows determines the next move. A cyst that has vanished needs no further action. One that is unchanged but still simple may be followed once more. One that has grown, or has developed solid components, moves out of the waiting category and into the investigation described earlier.

Postmenopausal cysts are also sometimes watched, but with a tighter leash: the NHS describes regular ultrasound and blood-test monitoring rather than a single check.

Some people ask whether medication can shrink a cyst. The Mayo Clinic is clear that hormonal contraception does not shrink an existing cyst. Because it suppresses ovulation, it may reduce the chance of new functional cysts forming, which is why a clinician might suggest it for someone who develops them repeatedly. Whether that is appropriate depends on the individual and is a decision for the prescribing clinician.

When is surgery recommended, and what are the options?

Surgery enters the conversation for a handful of reasons, each of them concrete: the cyst is causing persistent pain, it is large enough to risk torsion, it has not resolved after monitoring, it has features on imaging that could indicate cancer, or it appeared after menopause and cannot be confidently called benign.

Two decisions shape the operation.

How to get in. Laparoscopy, or keyhole surgery, uses a few small incisions and a camera. The NHS describes it as the usual approach for most cysts, with faster recovery and less scarring. Laparotomy, a single larger incision, is chosen when a cyst is very large or when cancer is suspected, because it allows the surgeon to remove the growth intact and inspect the whole abdomen.

How much to remove. A cystectomy removes the cyst and leaves the ovary, the preferred option when fertility matters and the cyst appears benign. An oophorectomy removes the ovary, sometimes with the fallopian tube, and is more likely when cancer is a concern, when the cyst has destroyed most ovarian tissue, or after menopause when preserving the ovary offers less benefit.

Risks are those of any abdominal operation: bleeding, infection, injury to bowel or bladder, and anesthetic complications, all uncommon but real. The alternative to surgery is almost always continued monitoring, which trades the small risks of an operation for the smaller but nonzero risk of missing a change.

If cancer is confirmed at surgery, the procedure may be extended and further treatment planned by a specialist team. Every one of these choices is made with the patient, weighing age, symptoms, imaging, and plans for children, and the final decision sits with the treating team and the person on the table.

When should you see a doctor about an ovarian cyst?

Most cysts are found by accident and need only a follow-up scan. Some situations, though, deserve an appointment rather than patience, and the distinction is not hard to learn.

Book a routine appointment if you notice:

• Pelvic pain, pressure, or a dull ache on one side that lasts more than a few weeks or keeps recurring.
• Bloating, abdominal swelling, feeling full quickly, or needing to urinate more often, especially if these occur on most days for several weeks (the NHS threshold is more than 12 times a month).
• A noticeable change in your periods, such as heavier, irregular, or missed cycles, that persists beyond one or two months.
• Pain during sex or difficulty conceiving after a year of trying (six months if over 35).
• Any vaginal bleeding after menopause, however light.

Seek same-day or emergency care if you experience: sudden severe abdominal or pelvic pain; pain with fever or repeated vomiting; dizziness, fainting, rapid breathing, or cold clammy skin; or pain that steadily worsens over hours. These can signal a ruptured cyst with bleeding or a twisted ovary.

One more prompt, easy to overlook: if you have a strong family history of ovarian or breast cancer, or a known inherited gene change, mention it whenever a cyst is discussed. It does not make your cyst more likely to be cancerous in itself, but it changes how carefully a clinician will want to look.

My own view, having watched this topic for years, is that the most useful skill is not memorizing scan features but honoring persistence. A symptom that will not leave is worth a conversation, and the conversation is almost always shorter and more reassuring than the worry that preceded it.

Frequently asked questions

What are the symptoms of a cancerous ovarian cyst?

There is no symptom unique to a cancerous cyst; the signs overlap with benign cysts and digestive problems. What clinicians watch for is persistence: bloating, pelvic or abdominal pain, feeling full quickly, and urinary urgency that occur on most days for several weeks and gradually worsen, particularly after menopause. Unexplained weight loss or fatigue alongside these adds concern. Any such pattern warrants a scan, because symptoms alone can never confirm or exclude cancer.

Can ultrasound tell the difference between ovarian cysts and cancer?

Ultrasound cannot see cancer cells, but it can identify features that make cancer more or less likely. Simple cysts with clear fluid and thin, smooth walls are almost always benign. Solid areas, thick internal divisions, irregular walls, blood flow into solid tissue, or fluid in the abdomen raise suspicion. Benign cysts such as dermoids and endometriomas can look complex, so uncertain scans are usually followed by blood tests, MRI, or surgical removal for a definitive answer.

How do you find out if an ovarian cyst is cancerous?

The only definitive method is removing the cyst or ovary and examining the tissue under a microscope. Before that, clinicians combine transvaginal ultrasound, blood tests such as CA-125, menopausal status, and sometimes MRI into an overall risk estimate. Needle biopsy through the skin is generally avoided because puncturing a cancerous cyst could spread cells. Being scheduled for surgery to find out what a cyst is does not mean cancer has been diagnosed.

What are the first warning signs of ovarian cancer?

The NHS lists four core symptoms: persistent bloating or a swollen tummy, pain or tenderness in the abdomen or pelvis, feeling full quickly or losing appetite, and needing to urinate urgently or more often. The key qualifier is frequency, more than 12 times a month. Other signs include indigestion, changes in bowel habit, back pain, unexplained tiredness, weight loss, and any vaginal bleeding after menopause. Persistent clusters of these symptoms deserve a doctor’s assessment.

Can an ovarian cyst cause bleeding between periods?

Yes. Functional cysts are made of hormone-producing tissue, and a cyst that keeps secreting estrogen or progesterone can throw the uterine lining off schedule, causing spotting, delayed periods, or heavier or lighter flow than usual. The NHS lists these menstrual changes among cyst symptoms, and they typically settle once the cyst resolves. Bleeding after menopause is different and always needs prompt assessment, even though it is more often caused by the uterine lining than the ovary.

Do ovarian cysts make it harder to get pregnant?

Most do not. Functional cysts are a byproduct of ovulation and do not impair fertility, and dermoids and cystadenomas rarely interfere unless they become very large. The exceptions are endometriomas, which signal endometriosis and can reduce ovarian reserve and distort pelvic anatomy, and polycystic ovary syndrome, a hormonal condition that disrupts ovulation. Surgery on an ovary can also remove some egg-containing tissue, so anyone planning a pregnancy should raise it before treatment decisions are made.

Are ovarian cysts after menopause more likely to be cancerous?

The chance is higher than before menopause, though most postmenopausal cysts are still benign. Because the ovary no longer produces follicles, a new cyst cannot be explained by the menstrual cycle, and ovarian cancer becomes more common with age; the NHS notes it mainly affects women over 50. For that reason, postmenopausal cysts are monitored more closely with regular ultrasound and blood tests, and complex ones are more likely to be referred for surgical assessment.

What does a ruptured ovarian cyst feel like?

Typically sudden, sharp pain on one side of the lower abdomen, sometimes after exercise or intercourse, sometimes with no trigger. Most ruptures release a small amount of fluid, and the pain eases over hours to a couple of days. Warning signs of significant internal bleeding include spreading pain, dizziness or fainting, a racing heart, rapid breathing, and shoulder-tip pain. Those symptoms, or pain with fever and vomiting, require emergency care because torsion or heavy bleeding may be involved.

How long does it take for an ovarian cyst to go away?

Functional cysts usually shrink and disappear within a few months, often within two or three menstrual cycles, according to the Mayo Clinic. Clinicians typically arrange a repeat ultrasound a few weeks or months after the first to confirm resolution. Cysts that persist beyond that window, grow, or develop solid areas are unlikely to be functional and move into further evaluation. Non-functional cysts such as dermoids and cystadenomas do not resolve on their own.

Is PCOS the same as having ovarian cysts?

No, despite the name. Polycystic ovary syndrome involves many small immature follicles arranged around the ovary, not true cysts, and it is fundamentally a hormonal condition affecting ovulation, insulin, and androgen levels. Those follicles do not carry the cancer concern associated with complex cysts and are not treated by removal. PCOS can affect fertility through irregular ovulation, and it is managed as a metabolic and hormonal condition rather than a structural one.

References

• NHS: Ovarian cyst
• NHS: Ovarian cancer: Symptoms
• Cleveland Clinic: Ovarian Cysts
• MedlinePlus: Ovarian Cysts

This article is for general information only and is not a substitute for professional medical advice. Please consult a qualified doctor about your individual situation.