A cyst is a closed sac-like structure, an abnormal pocket of fluid, similar to a blister that contains liquid, gaseous, or semi-solid material. A cyst is located within the tissue, and can develop anywhere in the body and may vary in size.
An ovarian cyst is an accumulation of fluid within an ovary that is surrounded by a very thin wall. Any ovarian follicle that is larger than approximately 2cm is an ovarian cyst.
The majority of ovarian cysts are benign (harmless). Most premenopausal women and up to 15% of postmenopausal women are found to have ovarian cysts, but they typically occur most frequently during a female’s reproductive years. Sometimes ovarian cysts cause pain and bleeding. If the cyst is over 5cm big, it may need to be surgically removed.
There are two main types:
Functional ovarian cysts – the most common type. These harmless cysts form part of the female’s normal menstrual cycle and are short-lived.
Pathological cysts – these are cysts that grow in the ovaries; they may be harmless (benign) or cancerous (malignant). Regular pelvic examinations usually protect a woman from complications.
As most ovarian cysts present no signs or symptoms, they frequently go undiagnosed. Sometimes, even without symptoms, a cyst may be diagnosed during an unrelated pelvic examination or ultrasound.
The causes are different for each type of ovarian cyst, so we have to look at them one at a time.
Functional ovarian cysts
There are two types:
1. Follicular cysts
Follicular cysts are the most common. A female human has two ovaries which release an egg every month. The egg moves into the uterus, where it can be fertilised by a male sperm. The egg is formed in the follicle, which contains fluid to protect the growing egg. When the egg is released, the follicle bursts.
In some cases, the follicle either does not shed its fluid and shrink after releasing the egg, or does not release an egg. It swells with fluid, becoming a follicular ovarian cyst. Typically, one cyst appears at any one time and normally goes away within a few weeks (without treatment).
2. Luteal ovarian cysts
These are much less common. After the egg has been released it leaves tissue behind. Luteal cysts can develop when the corpus luteum fills with blood. In most cases, this type of cyst goes away within a few months. However, it may sometimes rupture, causing sudden pain and internal bleeding.
Dermoid cysts are the most common type of pathological cyst for women under 30. Cystadenomas are more common among women aged over 40.
1. Dermoid cysts
These are bizarre tumours, usually benign. The cell can give rise to all orders of cells necessary to form mature tissues. Dermoid cysts contain hair, skin, bone and other tissues (sometimes even teeth). A totipotential germ cell can develop in any direction. They are formed from cells that make eggs. These need to be removed surgically.
Cystadenomas are ovarian cysts that develop from cells that cover the outer part of the ovary. Rather than growing inside the ovary itself, cystadenomas are usually attached to the ovary by a stalk. Although they are rarely cancerous, they need to be removed surgically.
These may increase the risk of developing ovarian cysts:
Endometriosis – This is a condition in which cells that are normally found inside the uterus are found growing outside of the uterus. That is, the lining of the inside of the uterus is found outside of it. Endometrial cells are the cells that shed every month during menstruation.
Polycystic ovarian syndrome (PCOS) – In this condition many small and harmless cysts develop on the ovaries, caused by a problem with hormone balance produced by the ovaries. People with PCOS have a higher risk of developing ovarian cysts.
• Pelvic pain – A ruptured ovarian cyst may present similar signs and symptoms to those of appendicitis or diverticulitis. In the vast majority of cases, ovarian cysts are small and benign (harmless); there will be no signs or symptoms. Even if there are symptoms, they alone cannot determine whether a patient has an ovarian cyst.
There are several other conditions with similar signs and symptoms, including endometriosis, pelvic inflammatory disease, ectopic pregnancy or ovarian cancer. A ruptured ovarian cyst may present similar signs and symptoms to those of appendicitis or diverticulitis.
• Irregular menstruation – periods may also become painful, heavier or lighter than normal
• Dyspareunia – pelvic pain during sexual intercourse
• Pain when passing a stool
• Pressure on the bowels
• Some pregnancy symptoms – breast tenderness and nausea
• Bloating, swelling, or heaviness in the abdomen
• Problems fully emptying the bladder
• Pressure on the rectum or bladder – the patient may have to go to the toilet more often
• Hormonal abnormalities – in some rare cases the body produces abnormal amounts of hormones, resulting in changes in how breasts and body hair grow.
Watchful waiting – This is recommended, especially if the woman is pre-menopausal, and she has a small functional cyst (2-5cm). An ultrasound scan will be carried out about a month or so later to check it, and to see whether it has gone.
Oral contraceptives – To reduce the risk of new cysts developing in future menstrual cycles, the doctor may recommend birth control pills.
Cancer treatment – If the cyst is cancerous, the patient may need to have more organs and tissue removed, including the ovaries, uterus, the omentum and some lymph nodes.
Blood test – If there is a tumour present blood levels of CA125 (a protein) will be elevated.