What are ovarian cysts?

Ovarian cysts are fluid-filled sacs that form within the ovary. They vary in size and content, and may be benign or malignant. Most cysts are asymptomatic and non-cancerous, and resolve spontaneously without any treatment.

What are the types of ovarian cysts?

Functional cysts develop as part of a normal menstrual cycle. These include:

1. Follicular cysts
   

   New follicles develop during the start of each menstrual cycle. Each contains fluid that protects a developing egg, which is released at the time of ovulation. If the follicle fails to release the egg, it may continue to grow and form a follicular ovarian cyst.

2. Corpus luteum cysts
   

   If ovulation takes place, the follicle develops into a corpus luteum. This produces progesterone, which modifies the womb lining to prepare it for pregnancy. The corpus luteum typically dissolves if pregnancy does not take place, but may occasionally bleed or swell with fluid to form a corpus luteal ovarian cyst.
   
   The majority of functional cysts resolve spontaneously over two to three menstrual cycles. However, some may continue to grow or even twist or rupture and cause acute symptoms.

Polycystic ovaries are ovaries containing multiple small follicles. This may be seen in conjunction with irregular menses, subfertility and symptoms of hormonal imbalance like oily skin, acne and increased hair growth.

Benign ovarian cysts include:

1. Endometriotic cysts

   Endometriosis occurs when cells from the womb lining develop outside the womb. Deposits of these cells on the ovary can result in the formation of endometriotic cysts. These cysts contain thick, dark brown material, and are frequently adherent to surrounding structures such as the uterus, opposite ovary or intestines, which may make surgery more challenging.

2. Dermoid cystssia
   

   Dermoid ovarian cysts develop from germ cells, which are cells that are able to develop into any type of body tissue. They may therefore contain various types of tissue including teeth, hair and fat, and are more commonly seen in younger women.
   

3. Cystadenomas
   

   These arise from the outer surface of the ovary and may contain fluid or mucoid contents.
   A proportion of ovarian cysts are cancerous (malignant). Pregnancy, breastfeeding, usage of the oral contraceptive pill, previous sterilisation and removal of the uterus are associated with a lower chance of developing ovarian cancer.