What are ovarian cysts?
Ovarian cysts are very common. Often people visualise 'cysts' as a serious ovarian issue, but in many cases, they will cause no problems at all, may be incidental findings, and resolve on their own without intervention.
Different types of ovarian cysts
Follicles are a normal part of a woman's ovaries. Each follicle houses an egg, and in women ovulating regularly, a follicle will burst each month (mid-cycle), releasing an egg. The egg may be picked up by the fallopian tube. If a woman has had unprotected sex, a sperm may reach and fertilise the egg in the tube. It then develops a further 3-5 days in the tube before reaching the uterus.
The outside of a follicle contains cells which produce estrogen and progesterone. This hormones regulate a woman's menstrual cycle and prepare the inside lining of the uterus (endometrium) for pregnancy. A woman's ovaries actually contain many thousands of follicles. Each month a handful are potentially available for ovulation. 1-2 follicles may develop from 2-6mm diameter to 20-24mm diameter before they burst. Some woman are aware of ovulation, which may be a sharp or full pain in the lower part of the abdomen. This may be termed 'mid-cycle' pain, or 'mittelsmertz'.
These are most common in reproductive age women. They are filled with clear fluid. This fluid has a classic 'black' appearance on ultrasound scan. Simple cysts will normally resolve without intervention, but are occasionally removed if large, do not resolve or are causing symptoms such as pain.
These cysts most commonly originate from recent ovulation. When a developed follicle bursts, some bleeding commonly occurs in the cyst remnant. This cyst remnant (the corpus luteum) actually has a very important function, it produces hormones (estrogen and progesterone) in very large amounts to support an egg if it is fertilized by a sperm.
Some women will have more bleeding than usual, which may collect in the cyst capsule. It is essentially a 'bruise' on the ovary. Generally this will simply resolve over the next few weeks, but in rare cases they may cause substantial bleeding requiring emergency surgery.
These are corpus luteum cysts that continue to produce hormones (estrogen and progesterone). They may cause irregular or prolonged vaginal bleeding, and affect the regularity of a woman's menstrual cycles until they resolve. Most will resolve spontaneously.
These are sometimes referred to as 'chocolate cysts'. They are called this as the material inside the cyst has the consistency of melted chocolate. It is in fact blood, caused by accumulated menses. Endometriomas in most cases are indicative of moderate to severe endometriosis. If an endometrioma is present, it is highly likely endometriosis is present elsewhere in the pelvis.
These are a common benign cysts of the ovary and are the most common ovarian tumour of women in their 20s and 30s. Dermoid cysts are 'mature' meaning they may contain many different elements such as hair, sebaceous fluid, teeth and skin.
Benign tumours are an abnormal or cancerous growth, but do not 'spread' around the body (metastasise). They only way to definitively tell if an ovarian cyst is a benign tumour is through surgical removal and examination in a laboratory (histology). Scans and blood tests can give indications of the nature of a cyst, and its likelihood of being a malignant cancer. Some benign ovarian cysts are dermoid cysts, serous cystadenomas and mucinous cystadenomas.
Ovarian cancer is more common in women in the menopause. The diagnosis is made through examination of the cyst in the laboratory, however ultrasound and blood tests are helpful to determine the likelihood of cancer. Often there are little or no symptoms. Some patients may present with abdominal swelling, weight loss, nausea or lethargy. Younger women may also develop ovarian cancer, however the chance is far lower.
- None: women with ovarian cysts most commonly have no symptoms at all. They may be picked up as an incidental finding on examination or ultrasound scan. Simple cysts less than 2.5 - 3cm are likely transient, and will resolve on their own without intervention.
- Pain: only rarely will a woman with an ovarian cyst present with pain. The chance of a cyst causing pain depends on what is causing the cyst and also its size. Some cysts (such as dermoid cysts) present more commonly with pain, but are still largely incidental findings. A cyst may cause pain through rupture, torsion, or pressure on other structures.
- Rupture: this is where a cyst bursts releasing its contents in the pelvis. Pain may be of sudden onset and move through in to the lower back and bladder. They may cause abdominal swelling and bloating, pain moving bowels, and nausea. Occasionally severe pain can occur with a low-grade fever and vomiting.
- Torsion: this is where a cyst may twist on its base, preventing blood flow to the cyst and tissue within. Pain is caused through the tissue degenerating from lack of oxygen and nutrients. Pain is generally sudden, severe, and associated with nausea and vomiting. Torsion will generally only occur when a fair size ovarian cyst is apparent, around 5cm. Very large cysts (>10cm) rarely tort due to a lack of 'room to move'.
- Pressure: a cyst may put pressure on other structures in the pelvis. Pressure on the bladder may cause a feeling of wanting to pass urine often, sense of 'urgency' to urinate, or having to get up overnight to urinate (more often than previously).
The treatment recommended depends on a number of factors, including the nature of the cyst, potential for sinister pathology (such as cancer), age of the patient and presence of symptoms.
Most cysts are removed laparoscopically (keyhole surgery), but some may be via a laparotomy (larger incision on the abdomen).