Endometriosis affects one in 10 women of reproductive age here in the UK - that's roughly 1.5 million women. It causes sufferers to experience painful or heavy periods, pain during sex and fertility issues - all of which can have a drastic effect on their lives.
What is endometriosis?
Endometriosis is a common condition where tissue that behaves like the lining of the womb is found outside of the womb.
These pieces of tissue can be found in many different areas of the body, but they are most commonly found on the ovaries, on the lining of the pelvis behind the uterus and covering the top of the vagina, says the NHS Choices site.
The exact cause of endometriosis is unknown, but there are several theories.
One of them is that the womb lining (endometrium) flows backwards through the fallopian tubes and into the abdomen instead of leaving the body as a period. This tissue then embeds itself on the organs of the pelvis and grows.
Another is that the condition is hereditary, being passed down through the genes of family members.
Symptoms of endometriosis
Symptoms of endometriosis include painful periods or heavy periods; pain in the lower abdomen, pelvis or lower back; pain during and after sex; bleeding between periods and difficulty getting pregnant.
Other lesser-known symptoms include: long-term exhaustion and tiredness, discomfort when urinating or passing stools, bleeding from the back passage or finding blood in your stools and coughing blood (this occurs in rare cases where the endometriosis tissue is in the lung).
Diagnosis and treatment
There is no cure for the condition and treatment usually combines a mixture of painkillers and hormone treatment to help make daily life more manageable.
Dr Helen Webberley, the dedicated GP for Oxford Online Pharmacy, told HuffPost UK Lifestyle that the condition can be very difficult to diagnose because of the common symptoms - namely abdominal pain and heavy periods - which can be attributed to many other conditions.
Additionally, she said there are cases where women suffering from endometriosis might not have any symptoms at all.
"There is no 'test' that GPs can do," explained Dr Webberley. "It can only be diagnosed with a laparoscopy - or sometimes on a very detailed ultrasound scan - and we can't justify the risk of this procedure on everyone with simple abdominal pain or heavy periods."
She added, however, that if there are any worrying symptoms such as "severe pain that is not cyclical or bleeding between periods or after sex" then this needs to be investigated.
Dr Webberley also mentioned that the contraceptive pill could prove to be an effective treatment for mild endometriosis.
"The treatment of mild to moderate endometriosis is to suppress ovulation and stop the monthly cycle of endometrial build up and the best way to do this is to use the contraceptive pill, something which can be done without the need for invasive tests," she said.
"If this stops the pain and bleeding then you are closer to a diagnosis. Suppressing ovulation will stop the damage that endometriosis causes, saving the fallopian tubes and helping to promote fertility."
She added: "We can't send everyone for a laparoscopy, so we are able to use the treatment (the pill) as both a test and a cure."
Lack of research into the condition means many women are left suffering without the support they need.
According to a survey by Endometriosis UK, 25% of its membership had considered suicide because of the condition.
Meanwhile a study in 2011 found that endometriosis accounts for a significant loss of productivity among sufferers, equating to roughly 11 hours per woman, per week.
Jane Hudson Jones, chief executive of Endometriosis UK, previously told the Guardian: "It can be absolutely devastating.