If you have concerns about Ovarian Cysts, please find this section as a guide to help answer some of your questions. We hope these FAQs and short video will be a helpful resource, however should you require further assistance, please do call on on 020 7637 1075.

Video: Ovarian Cyst
When is an ovarian cyst not an ovarian cyst?
Occasionally cysts in other structures will ‘mimic’ ovarian cysts. Common examples of this are fimbrial cysts on the end of the fallopian tube, and a hydrosalpinx which is a fluid collection within the fallopian tube. Fibroids sometimes occur in the tissue next to the ovary called the broad ligament and so appear to be attached to the ovary.
What are the different types of ovarian cysts?

Functional cysts

Functional ovarian cysts develop because of a slight alteration in the normal function of the ovary. These cysts occur in women during the reproductive years and are very common. To understand these cysts you need to know a little about the normal ovarian cycle. In the first half of the menstrual cycle follicles develop within the ovary. These follicles are small cysts filled with fluid in which the eggs are maturing. Usually one follicle becomes dominant and just before ovulation when the egg is released it is over 20mm in diameter. If the egg is not released properly, the follicle may persist as a follicular cyst which may reach 5 or 6cm in size. Follicular cysts are usually very thin-walled and simple in appearance and will usually resolve spontaneously within a few weeks. After ovulation, when the follicle has ruptured to release the mature egg, the follicle becomes the corpus luteum, which may appear as a cyst on ultrasound examination. Often bleeding occurs into the cyst when it is referred to as haemorrhagic. Luteal cysts are often confused as being abnormal, but they will usually resolve spontaneously without treatment within a few weeks.


When endometriosis affects the ovaries, one or more cysts may form within the ovaries. Old blood within these cysts breaks down to form a thick chocolate-coloured fluid, hence the name, ‘chocolate cysts’. They may persist for many years and tend to get slowly bigger, if left untreated.

Dermoid cysts

These arise from the egg or germ cells within the ovary. Dermoid cysts are common in young women and are completely benign. They are called ‘dermoid’ because they tend to contain many elements from the skin and its accessory tissues. A dermoid cyst is typically filled with a fatty fluid, like sebaceous secretion, and may contain hair and teeth-like structures. This produces a classic appearance on a plain x-ray with what appear to be teeth within the pelvis. Because these tumours arise from eggs that are able to develop eventually into any tissue, many other tissues may be found including cartilage, glands and nervous tissue. They may occur in both ovaries.


These are the most common ovarian tumours and arise from surface layer of the ovary called the serosa or epithelium. These cysts can occur at any age and are benign. They are subdivided into serous type that contains a thin fluid and mucinous type which contain a thick gelatinous fluid. They tend to get bigger slowly over time and may become as large as a fully pregnant uterus.

Polycystic Ovarian Syndrome

This is a condition where a hormone imbalance is associated with the formation of many small cysts around the surface of the ovaries. The cysts themselves do not cause any problem and are merely a manifestation of the underlying imbalance, and therefore do not need to be treated.

Other cysts

There are many different less common types of ovarian cysts other than those listed above.
What symptoms do ovarian cysts cause?
Most ovarian cysts cause no symptoms at all and many are discovered because of scans for other reasons. The following symptoms may be noticed.
  • Lower abdominal pain which may be intermittent, but more usually constant
  • Irregularity of the menstrual cycle or bleeding between periods
  • Pain with sex
  • Abdominal swelling or a lump in the abdomen
Can cysts cause any problems?
An ovarian cyst can:
  • Burst. This may cause sudden pain that settles after a few hours without treatment. This usually occurs in simple fluid filled cysts and is not dangerous as the fluid is just absorbed by the body. Rarely, the ovary may continue to bleed and may need treatment.
  • Be bled into. This causes a sudden onset of pain that may last for many hours. This most commonly occurs in luteal cysts and will usually stop spontaneously. Providing this can be correctly diagnosed it often does not require any treatment. It may need careful monitoring in hospital.
  • Undergo torsion. When this happens the whole ovary is twisted with the cyst and the blood supply is quickly blocked. The ovary may untwist by itself which will restore the blood flow, but otherwise it is an emergency since the lack of blood will cause the ovary to die within a few hours.
These are all called “cyst accidents”.
How are cysts diagnosed?


An ultrasound scan is the most common investigation for an ovarian cyst. The scan shows some of the characteristics of the cyst and points to the likely type of cyst. An abdominal scan may be performed first, and is useful if the cyst is large. An abdominal scan also allows other structures in the abdomen to be visualised. A full bladder improves visualisation of the pelvic structures as the fluid in the bladder makes a kind of “window” to the pelvis. A transvaginal scan brings the ultrasound probe much closer to the pelvic organs and usually gives better detail of the ovaries, fallopian tubes and uterus. This scan should not cause any discomfort and does not require a full bladder. Ultrasound characteristics of ovarian cysts:
  • Thickness of the outer wall of the cyst. A simple cyst has a thin outer wall.
  • Irregularities in the cyst wall. A simple cyst has a smooth wall whereas a complex cyst may have some irregular nodules or thickening of the wall.
  • Internal divisions or “septae” are found only in complex cysts. These may be thin or thick and may also contain irregularities.
  • Solid areas are seen in some complex cysts.
  • The nature of the “fluid” filling the cysts varies and ultrasound can give some insight into this. Blood often looks very different to the thin fluid of a follicular cyst.
  • If similar cysts are present on both ovaries this may be significant.
  • Blood flow through various parts of the cyst can be measured by Doppler scanning and helps determine the nature of the cyst.
All the above characteristics are taken into account by the ultrasonographer who may be able to form a judgement on the type of cyst present. Such judgements are never 100% accurate and are sometimes very difficult. However they may give some guidance as to how to manage the cyst. The information gained by an ultrasound examination is very dependent on the skill of the person performing the scan. Most radiologists have areas of the body they are particularly interested in and develop skills in those areas specifically. Choice of the right person to perform a scan is important, particularly if the diagnosis is difficult. If a cyst appears simple, the ultrasound scan may be repeated at an interval of 4 to 6 weeks to see whether the cyst has resolved or increased in size.


This blood test measures the presence of a tumour antigen. The CA125 level may be elevated in ovarian cancer, although in 30% of early cancers it is not elevated at all. It is also elevated in many other circumstances including endometriosis. The CA125 level changes with the normal menstrual cycle and is therefore more useful after the menopause.


Magnetic Resonance Imaging is an alternative method of scanning the ovaries. It provides information that complements the ultrasound findings. The MR image differentiates between different tissue types by imaging the molecular characteristics of tissue. It can identify fat, blood and other tissues. If the cyst is complex MRI may be useful in helping to determine what type of cyst is present.

Treatment of ovarian cysts

The treatment of an ovarian cyst depends on what type of cyst is present. Unfortunately, even with the very best imaging and assessment it is not possible to be certain about the nature of an ovarian cyst. The treatment has to be decided on the basis of probability of various cyst types rather than certainty. One of the key issues is the possibility that the cyst is cancerous. With most simple cysts this is very unlikely, but often this possibility cannot be completely excluded.A simple “Risk of Malignancy Index” has been developed which takes into account the CA125 level, menopausal status and ultrasound findings. This is a guide that can be useful in raising suspicion of malignancy in some cases, although it is not very helpful with endometriosis as the ultrasound appearances are often complex and CA125 may be raised significantly. Other risk scores have been developed which perform better than the RMI. With most ovarian cysts diagnosed, the suspicion of malignancy is very low and the women can be reassured.
When is surgery necessary?
Functional cysts usually resolve spontaneously over several weeks or months. If a cyst is thought to be functional a repeat scan in 4 to 6 weeks is usually arranged. It is only necessary to remove a simple cyst if it persists over several months or causes symptoms.The factors that determine whether a cyst should be removed are
  • Complexity. If an ovarian cyst has septae, solid areas, an irregular wall or increased blood flow.
  • Size. Over 5 cm is considered more significant.
  • Symptoms attributable to the cyst
  • The nature of the cyst suggesting whether it will resolve spontaneously or not.
  • Risk that the cyst is cancerous
What type of surgery is best?

Laparoscopic (Keyhole) surgery

Many cysts can be removed using keyhole surgery. This allows dissection and removal of the cyst without an abdominal incision with a quicker return to normal activities. The operation is performed using a telescope in an incision in the umbilicus and usually two other ports lower down on the abdomen. The cyst is placed in a bag and the fluid removed before the cyst wall is removed through one of the ports.

Robotic surgery

Recently robotic surgery has been used to improve keyhole surgery. This approach allows very much more precise surgery with even quicker recovery. Robotic surgery can be performed through a single port in the umbilicus making it virtually “scarless”.

Open surgery

If the cyst is possibly a cancer, even if that risk is low, an open operation is usually better, as laparoscopic surgery is more likely to spread the tumour than an open operation. Often this can be performed through a small incision and return to normal activities is almost as quick as with keyhole surgery.
Will I need any follow-up?
Most women are seen for one or two visits after surgery to make sure that they have healed well. The risk of a further ovarian cyst depends on the nature of the cyst. Most ovarian cysts have no tendency to recur and so further follow-up is not necessary.
Does removal of an ovarian cyst affect fertility?
Removing a cyst from one or both ovaries should not affect the function of the ovary and so fertility and periods should not be affected. Sometimes surgery can cause adhesions where organs within the abdomen stick together. If adhesions occur around the ovaries or fallopian tubes, they can affect the transfer of eggs released from the ovaries to the fallopian tubes. During surgery it is important to handle the tissues within the pelvis gently to avoid damage to the surface and to reduce the risk of adhesion formation. With careful surgery, adhesions that affect fertility are very uncommon unless another abnormality is present such as endometriosis or pelvic infection.