In the aftermath of Easter the very word chocolate conjures up visions of sweet filled eggs and cute edible bunnies. However, chocolate cysts are far removed from these festive ideas. They are a type of ovarian cyst caused as a result of endometriosis and the ‘chocolatedness’ is in fact old blood. The cysts, also known as endometriomas, are benign but they can lead to other problems such as infertility.

Endometriosis is a condition which affects aroundtwo million women of reproductive age in the UK. Cells from the endometrium or lining of the womb slough off and migrate to other parts of the body, in this case, the ovary. These cells remain endometrial so, with each period, they first divide and thicken and then shed as a bleed. There is no escape for this blood, so each month the cyst grows as it fills with the trapped fluid.

There is no one accepted cause of endometriosis but genetic, immune system, hormonal and environmental factors are all believed to play a part. Retrograde menstruation seems to be an important factor in at least some of the cases. This is where some of the menstrual bleed flows backwards up the fallopian tubes instead of out through the vagina. However, some people think this is a common phenomenon but most women manage to rid themselves of this stray material so it never causes problems. Whatever the reason for it embedding on the walls of the ovaries this explanation does provide a convincing answer as to how it reaches this location.

Some women are unaware that they have chocolate cysts as they suffer no symptoms at all. They may only be identified when they are investigated for infertility problems. However, for others, the condition results in lower abdominal pain, varying from mild to severe, which may be constant or fluctuate with the menstrual cycle. While pelvic pain is the most common symptom the sufferer may also experience nausea, vomiting, headaches, prolonged and heavy periods, chronic fatigue, painful legs especially thighs, depression or other diverse complaints. As can be seen, for some women it is a debilitating condition. Generally as the cysts grow bigger the pain increases as it presses more on the ovary tissue and even starts to replace the ovarian tissue. This is how it causes infertility, as the ovary is unable to function normally so egg or ovum production is either reduced or halted. Eventually these chocolate cysts get so big that they burst, spilling their contents into the pelvic cavity and over the bladder, bowel and uterus. At the point of bursting there is a sudden onset of sharp severe abdominal pain. Afterwards there may be an increase in chronic pain as adhesions form in the cavity. These adhesions further reduce fertility.

Diagnosis of these ovarian cysts is generally made through a detailed medical history, a pelvic examination, ultrasound scans, maybe a laparoscopy and blood tests. Through these a definitive diagnosis should be made so the woman can then consider the treatment options open to her.

Unfortunately there is no cure for endometriosis and for a woman who has completed her family, is nearing the menopause and has few symptoms it may be best to opt for no treatment, as it is likely to resolve itself. For a woman who does not want children but has symptoms which are disrupting her life there are medicines which can reduce them. Painkillers such as ibuprofen can help bring the pain under control. Hormonal treatments can reduce the size of the cysts and so alleviate symptoms. These work by reducing oestrogen levels in the body, so are no use if the woman wishes to become pregnant. Typically the medicines used are gonadotrophin-releasing hormone analogues such as Buserelin, progestogens such as Norethisterone or androgens such as Danazol. All of these treatments cause some side-effects and any resulting improvement in the condition is likely to last only as long as the treatment is continued.

For those women who either wish to conceive, or whose symptoms are severe and not responding to medical treatment, surgery is an option. It may be possible to cut out the cyst(s) whole but, if not, the contents may be destroyed by a laser or electric current. Usually this would be done via keyhole surgery. The endometriosis may return after surgery but it may offer an opportunity for pregnancy to occur. In extreme cases the removal of the uterus and ovaries (hysterectomy and oophorectomy) may be necessary although this then ends all hope of child-bearing.

To conclude, chocolate cysts are caused by endometriosis where the uterine lining tissue has migrated to the ovaries. It can give rise to few or severe symptoms and is a cause of infertility. Treatment can be medical – painkillers and or hormones – or surgical and although there is no cure, the condition can be alleviated.