The ‘normal’ ovarian cyst
Each month (for women not on the pill or using some other forms of hormonal contraception or treatment), an ovary produces a follicle. This is where the oocyte (or egg) will grow and develop and then be released in preparation to join with a sperm to create an embryo. This follicle is a cystic structure. Cyst simply means a fluid filled space that is lined with a certain cell type. So, on an ultrasound, these follicles may be seen and are often referred to in reports as ‘cysts’. The terminology may confuse women (and some doctors) and this type of ‘cyst’ does not require any treatment. The usual size is up 10-25 mm, although occasionally they may grow larger.
There are certain features on an ultrasound, such as blood flow patterns and the nature of the contents of the cyst that help gynaecologists to determine if observation only or treatment is needed. The same ovary may produce these follicles month after month and it is a myth that the ovaries alternate in the production of follicles.
Once the follicle releases its oocyte, then the cystic space fills with blood and becomes the corpus luteum (literally meaning ‘yellow body’). This would support a pregnancy in the early stages of development if an embryo is formed, but if no pregnancy occurs, then the corpus luteum (which is literally a bruise in the ovary) breaks down and becomes resorbed into the body – just like any bruise. This takes time and the ‘cyst’ will shrink and disappear with time. This is a normal and natural process and surgery is not required. When there is doubt and there are no other warning features, a repeat ultrasound will usually help to determine this normal from an abnormal cyst, since the normal cyst will always shrink with time.
Abnormal ovarian cysts
Of course, there are a number of different types of abnormal ovarian cysts. These may present due to pain, swelling (the feeling of a mass), pressure on the bladder or bowel, or bloating and generalised symptoms. They may also be asymptomatic and found during an ultrasound or other scan on the pelvis for another reason (an incidental finding) or a routine pelvic examination at the time of a Pap smear with your doctor.
Some common types of ovarian cysts include:
- Dermoid cysts;
- Endometriomas (endometriosis of the ovary).
Other important types of ovarian cysts include cancerous cysts, which are in fact not especially common, but often serious since they are diagnosed late in their course due to non-specific symptoms. We will discuss this in a separate blog.
Cystadenomas: These are a group of cysts that may grow very large. Symptoms are similar as for other types of cysts and these cells arise from the lining cells of the ovaries, rather than the cells that form eggs (called germ cells). This is a common type of cyst and they may occur at any age, although do increase as a woman gets older. They are thought to be pre-cancerous, although the rate of progression is very slow. One of the difficulties is in determining whether an ovarian cyst is benign (non-cancerous) or malignant (cancerous) and this often requires the cyst to be removed surgically and examined under a microscope.
It is a usually a combination of factors such as age, family history, ultrasound findings and other risk factors that suggest a course of action when an ovarian cyst that may be a cystadenoma is found. If these cysts grow very large, then they may twist (called torsion) which cuts off the blood supply to the ovary and causes severe pain and a woman will often present as a medical emergency when this happens. These cysts should be removed surgically and this may be achieved by laparoscopy with either the cyst only being removed or the entire ovary, again depending on a variety of factors. You should discuss further with your doctor if this is one of the potential diagnoses for your ovarian cyst.
Dermoid cysts: Dermoid cysts are often asymptomatic but may cause an ache or pain in the pelvis and may become large. These cysts are from the ovarian cells that make a baby and therefore they can contain any type of tissue. Most commonly these tissues are fat and hair, but also teeth, bones and skin may be found. Because they may create any type of tissue, they often have a very particular appearance on an ultrasound and are quite straightforward to diagnose. The chances of these being malignant (cancerous) is very low (about one cyst/thousand), however they do not respond to any drug treatment, usually grow and are removed surgically – often when they are between 3-6 cm.
Very small cysts (0.5-2 cm) are usually observed, since they can be difficult to remove with damage to the ovary more likely when they are small, compared to when they are big. Generally this type of cyst will always grow – although the rate may be very slow and they should be removed before they get too large (>6cm) when the risk of twisting (called torsion) increases and there is a risk of permanent ovarian damage or even loss.
Endometriomas (endometriotic cysts of the ovaries): Endometriomas are in fact not true cysts at all. This is a technicality only, since it relies on the presence of a particular type of cell, which is absent in an endometrioma. However, for all intensive purposes, endometriomas form when there is a collection of fluid that sits in the ovary, nearly always with adhesions to the wall of the pelvis and may contribute to pain and or infertility. Since this type of cyst grows from ovulations, they may present very early at a small size since they often cause adhesions and pressure builds within them rapidly. They have a commonly recognised appearance on ultrasound and occur in about 15-20% of women who have endometriosis.
Once present, there is no medical treatment to reverse them, however drug treatment may slow or stop their continued growth and reduce or stop symptoms completely and no further treatment is needed. For ovarian endometriomas that continue to grow, are very large or in certain situations with fertility, surgical removal is often recommended. Studies have shown that treatment of this type of cyst may in fact remove a part of the ovarian wall and therefore some oocytes (eggs) and whilst this does reduce the overall number of eggs, the chances of pregnancy have been shown to be the same as when they are not treated – perhaps because of an increased quality of the remaining eggs be removing toxic materials (such as iron compounds) from eggs growing close by.
Ovarian cysts are a common issue for women and the exact treatment will vary depend on your individual factors. You should discuss this with your Alana doctor who will give you specific information and guide you through the best treatment options for you.