A condition in which fragments of the endometrium (the lining of the inside of the uterus) are found in other parts of the body, usually in the pelvic cavity. Endometriosis can cause infertility in up to two in five affected women.
Incidence and causes
Endometriosis most commonly occurs in women who are aged between 25 and 40. The cause of the disorder is not clear. In some cases, it is thought to be due to the failure of certain fragments of the endometrium, shed during menstruation, to leave the body. Instead, they travel up the fallopian tubes and into the pelvic cavity, where they can adhere to and grow on any pelvic organ. These displaced patches of endometrium continue to respond to hormones that are produced in the menstrual cycle and bleed each month.
The symptoms of endometriosis vary greatly. Some women have no symptoms, but the disorder most commonly causes abnormal or heavy menstrual bleeding. There may be severe abdominal pain and/or lower back pain during menstruation. Other possible symptoms include dyspareunia (painful sexual intercourse), diarrhoea, constipation, and pain during defaecation. The internal bleeding causes pain and is followed by healing, which produces internal scarring. Bleeding into an ovary may result in a blood-filled ovarian cyst (known as a “chocolate cyst” because of its appearance). Endometrial tissue may be deposited in the muscular wall of the uterus (myometrium); this condition is called adenomyosis. In rare cases, there is bleeding from the rectum during menstruation.
Diagnosis and treatment
Laparoscopy (examination of the abdominal cavity with a viewing instrument) confirms the diagnosis. Certain drugs (including danazol, progestogen drugs, gonadorelin analogues, or the combined oral contraceptive pill) may be given to prevent menstruation. Local ablation of the endometrial deposits, using either laser treatment or electrocautery (the application of heat produced by an electric current), may sometimes be needed. If the woman is fertile, pregnancy often results in significant improvement. A hysterectomy (surgical removal of the uterus) and oophorectomy (surgical removal of the ovaries) may be offered if the woman does not have plans to have children.
Endometriosis in more detail
What is Endometriosis?
It is a condition where pieces of tissue similar to the lining of the uterus are present in places outside the uterus, where they shouldn’t be, usually in the pelvis. This tissue is like the tissue lining the uterine cavity, it looks similar under the microscope but according to gynaecology specialists it is not the same.
Patches or areas of endometriosis are known as lesions. A lesion is a medical word for an area of abnormality.
Endometriosis is a problem because it can lead to pain or scarring.
It is usually present on the peritoneum, which is the lining of the pelvic cavity. The commonest site for endometriosis is within the pelvic cavity. Typically, endometriosis lesions a present as small spots on the side walls of the pelvis, or on the surface of the pelvic organs etc.) These organs include the outside of the uterus, the ovaries, fallopian tubes, bowel, bladder, ureter and appendix. In more severe cases endometriosis can grow into the pelvic organs. However, it is important to note that endometriosis is not cancerous.
The organs of the pelvis are lined with a shiny membrane called the peritoneum. The peritoneum also lines the inside of the pelvic cavity and the abdomen. Most lesions of endometriosis are found on or within the peritoneum. When viewed directly through a laparoscope, endometriosis lesions are found to consist of different shapes, sizes and colours. Endometriosis is thought to be a different colour depending on the stage of development of the endometriosis. The different appearances are as follows:
Red lesions: These contain blood vessels, and have the appearance of small raised lumps. They sometimes look like a group of blood vessels. It is thought that red lesions may be the first stage in the development of endometriosis.
Clear lesions: These have the appearance of very small bubbles. They are a form of early endometriosis and can be difficult to visualise.
Black lesions: The peritoneum around endometriosis is irritated, causing scarring. Blood which is trapped within the scar tissue becomes black over time.
White lesions: Gradually, the scar tissue formed around the endometriosis blocks the blood vessels. The blood is reabsorbed by the body and a white scar is left.
Endometriosis or chocolate cysts: These are large clumps of endometriosis that form inside an ovary.
Peritoneal pockets or windows: These are areas that appear like a dent in the surface of the peritoneal lining. They are usually oval-shaped.
Invisible areas: If biopsies are taken of what looks like normal peritoneal lining, sometimes microscopic patches of endometriosis are found when examined under a microscope. This is especially likely when biopsies are taken in the region around obvious patches of endometriosis.
Young women tend to have clear, pink or red lesions of endometriosis. These are known to be the most active forms of endometriosis and they are the type most likely to lead to pelvic pain. They are also the most difficult lesions to identify during a pelvic laparoscopy. Older women usually have brown, white or black lesions. These have usually been present for a longer period of time.
Most lesions of endometriosis are small and thin. They usually measure 1-2 mm in diameter. Thicker and larger lesions are known as nodules. These usually measure from a few millimetres to a few centimetres across.
These are the largest type of endometriosis lesions. They can measure up to several centimetres across. The fluid inside the cyst is dark brown and looks quite like chocolate sauce. A chocolate cyst is also known as an endometrioma, endometrioid cyst or endometrial cyst.
This is when a woman has only a few lesions of endometriosis. Her endometriosis may cause any problems and it may have been diagnosed incidentally during an operation carried out for another reason, such as a laparoscopic sterilisation.
This lies between mild and severe endometriosis.
If a woman has many lesions or if the lesions are large then the endometriosis is severe.
The lesions are nearly always found within the pelvis. However, rarely lesions may be present in unusual places such as the umbilicus (navel or belly button), within a previous caesarean section scar or in the lungs. Very rarely they have been found in men who have taken oestrogen hormone treatments.
Endometriosis is particularly prevalent in Western countries. However it may be found throughout the world and amongst women of all ethnic backgrounds.
As mentioned above, it is important to emphasise that, although it may spread, endometriosis is not a form of cancer.
The word endometriosis is derived from the medical word for the lining of the womb (uterus) which is endometrium.’Endo’ means inside and ‘metra’ means uterus.The endometrium is the lining of the uterus that grows each month and then is shed each month causing a menstrual period. Although they appear similar under a microscope, a lesion of endometriosis is not the same as the lining of the uterus. The lesions of endometriosis rarely bleed and make different hormones from the normal endometrium.
How does endometriosis result in pelvic pain?
Medical specialists do not know for certain why endometriosis causes pain. It may certainly result in pain in the pelvis if it causes an ovary to stick to another organ within the pelvis. This is known medically as an adhesion. But, many women with endometriosis experience pain but do not have adhesions.
It is known that endometriosis lesions can produce chemical substances that cause irritation or scarring of the surrounding tissues or peritoneum. It is possible that these chemical lead to pain. Deeper and larger patches of endometriosis may impinge or press on small nerves within the pelvis leading to pelvic pain. This is particularly likely to happen if the endometriosis affects the uterosacral ligaments.
It is very commonly reported that endometriosis lesions cause pelvic pain because they bleed during a period and that the blood which is trapped has nowhere to go and causes pain. However, this reason is debated and contested by many gynaecologists who specialise in endometriosis. Many painful lesions of endometriosis do not bleed and bleeding is unlikely to be the cause of pain in most cases of endometriosis.
The pain from endometriosis may be confused with fibroid pain. If pelvic pain is experienced it is therefore important to have it thoroughly investigated. Fibroids will be obvious on an ultrasound scan, but to make a diagnosis of endometriosis a pelvic laparoscopy is required. This is a more invasive and difficult procedure to carry out than an ultrasound scan. In the investigation of pelvic pain, an ultrasound is usually carried out first.
Symptoms of endometriosis
The most common symptoms of endometriosis are:
- Painful periods – dysmenorrhoea
- Pain at ovulation
- Pelvic pain between periods
- Painful sex - dyspareunia
- Pain passing urine - dysuria
- Bleeding between periods
- Difficulty falling pregnant
- Pain when opening bowels
- Unusual symptoms
Fortunately, it is very rare for a woman to have all these symptoms.
Endometriosis can be present without symptoms, particularly if it is mild.
It is thought that about 1 in ten women will have endometriosis at some time during their life, but as this is usually mild they may never realise it or develop symptoms or have problems.
The commonest symptom is probably pelvic pain, but some women have no pain at all. Some women find it difficult to conceive, whilst others with endometriosis fall pregnant easily. If endometriosis is present, the symptoms depend on the location of the lesions within the pelvis. The symptoms of endometriosis seem to very so much that few women have the same experience.
If a woman does have any of these symptoms, it does not necessarily mean that she has endometriosis. The difficulty is that there are so many other conditions that may cause similar symptoms that there may be another cause or diagnosis. The only reliable means of diagnosing endometriosis is with a laparoscopy, but this involves an operation, which no one wants unless it is really necessary. It is therefore important to consider other causes carefully before arranging a surgical procedure such as a pelvic laparoscopy. There may be another explanation for the symptoms, so it is important to have a careful and detailed consultation or consultations with your doctor or gynaecologist. Usually the medical specialist will perform a physical examination and arrange investigations such as a pelvic ultrasound.
To give an example, most teenage girls experience period pains, but considerably less than 10% will have endometriosis. It is not practical, sensible or safe to carry out a laparoscopy on every teenage girl with period pain, but the occasional one will need to have a laparoscopy. Therefore doctors and gynaecologists make a careful assessment and try other treatments initially. A laparoscopy is only performed if initial treatments are ineffective or if the pain particularly severe or unusual. This reduces the need for unnecessary surgery on a lot of otherwise healthy young women. It does mean however, that there is a tendency for the diagnosis of endometriosis to be delayed.
Gynaecologists generally advise that a woman with pelvic pain should discuss this with their GP or family doctor at first. However, gynaecologists will say that you are the one with the pain, and you are best placed to decide whether you need a laparoscopy (rather than friends, family or GP). So if your symptoms are a major problem to you, and other treatments have not helped, then it is important to see a gynaecologist and request a laparoscopy.
Endometriosis anywhere within the pelvis can result in period pain (dysmenorrhoea). Period pain is the most common symptom. In fact, if you have period pain which is severe enough to seek advice from a doctor, then you have about a 50% possibility of having endometriosis. The risk is higher if there is a family history of endometriosis.
The other causes of period pain other than endometriosis include pain from the uterus itself due to prostaglandins, which are chemicals that cause pain and contraction of uterine muscle, adenomyosis due to changes like endometriosis in the wall of the uterus, and clot colic in women with very heavy periods with clots. Some women have more than one cause for their period pain.
Prostaglandins are chemicals that cause the normal period pain that young women suffer before having their first baby. This pain although ‘normal’ can be severe. Prostaglandin pain usually starts at the beginning of a period. It normally only lasts for one or two days, and is helped by taking the combined contraceptive pill or with analgesic medications such as ibuprofen or diclofenac. These non-steroidal anti-inflammatory (NSAID) medications are especially effective for prostaglandin period pain. If these pain killers relieve your period pain, then the likelihood of you having endometriosis is low.
Endometriosis period pain usually lasts longer than a day. There may be pain leading up to or right through a period. Period pain in the lower back is particularly common in women with endometriosis near the uterosacral ligaments. These ligaments pass from the uterus through to the part of the spine known as the sacrum. With endometriosis period pain, neither the contraceptive pill nor NSAID medications will help to ease or relieve the pain.
Adenomyosis period pain is more common in middle-aged women rather than young women, but this is not always true. Adenomyosis results in pain similar to endometriosis, but on laparoscopy no endometriosis is found. With adenomyosis the uterus is often slightly enlarged.
Therefore, if you are suffering period pain, a trial of NSAID medication or the contraceptive pill is a way of deciding whether a diagnosis of endometriosis is likely. If the pain is not relieved by a trial of these medications, then endometriosis is more likely and the decision to proceed with further investigation with a laparoscopy is much easier, and it is important to see a gynaecologist.
Ovulation is the time of the month when an egg is released from an ovary. It is normal to experience some pain at ovulation, but the pain should only last for a day, be much helped by period pain medication such as ibuprofen and swap sides approximately every second month. Doctors often refer to this pain as mittelschmerz (the German word for ‘middle pain’). Contraceptive pills usually work by stopping ovulation and therefore prevent ovulation pain, so be suspicious if ovulation pain is experienced whilst taking the contraceptive pill.
Endometriosis can sometimes form scar tissue that can stick pelvic organs to each other. The organs are stuck together by adhesions. If there are adhesions or endometriosis near an ovary then they can stick an ovary to the side wall of the pelvis, leading to pain that is not normal.
If pain is experienced on one side of the pelvis with periods and at ovulation then this may be a symptom of endometriosis near that ovary. Ovulation pain experienced on both sides of the pelvis at once may indicate endometriosis or adhesions around both ovaries. It can be even more complicated because there are some women who get crossover pain. This crossover pain is felt on one side of the pelvis when the actual problem or disease is on the other side of the pelvic cavity.
Pelvic pain between periods
Women who get pain ‘only’ with their periods can do their best to cope with the pain and live their lives around the days with period pain. But it is very hard to live with pelvic pain that is present on most days and that can come and go at any time. The longer you ‘live with the pain’ the greater the effect on your relationships, work, education, mood, self-esteem, leisure time and health. If you do have this frequent pain, it may or may not be endometriosis, but the pain does need to be investigated and treated.
How can you tell if the pelvic pains are endometriosis?
Pelvic pain experienced between periods that are secondary to endometriosis usually feels similar to period pain. It may not be as severe as period pain but it feels similar in nature and quality. As the next period becomes closer, the pain usually becomes more frequent and intense. The week following a period should be the best time of the monthly cycle. Pelvic pain experienced in one precise location, that follows this pattern often turns out to be endometriosis.
If the pelvic pain is present at any time of the month, despite when your period is due, then it is likely to be something other than endometriosis. Though recall that it is possible to have a combination of endometriosis and another medical condition. Pain that begins in the bowel, bladder, ligaments, uterus, veins, muscles or pelvic nerves all travel to the brain via similar neuronal pathways. It is therefore difficult for the brain to tell where each pain has arisen from and to separate out signals from more than one location. Many different pains may feel similar to the brain.
Dealing with and treating endometriosis only relieves those symptoms that are due to endometriosis. It is therefore important to have the pain thoroughly assessed, investigated and treated; otherwise pain arising from other causes or organs will simply persist.
Pain during sex
Painful sexual intercourse is known medically as dyspareunia. It is common in women who have endometriosis. In addition to the physical pain, there is also the emotional pain and guilt which is usually felt when women are unable to enjoy sex with their partner. Nobody feels like sex if they know that it is going to hurt.
There are many different reasons for dyspareunia, so the best person to consult initially is your family doctor or GP. Endometriosis rarely causes pain near the opening of the vagina and does not cause vaginal itching, a smelly vaginal discharge or vulval skin irritation. These symptoms are due to other medical conditions.
Painful intercourse due to endometriosis is felt deep inside the pelvis. It may be more severe in some sexual positions (depending on the location of the endometriosis) and may persist for 1 or 2 days afterwards. Pain during sex is particularly common if endometriosis is present behind the uterus near the top of the vagina. This area includes the uterosacral ligaments, the recto-vaginal septum and the pouch of Douglas.
Surgery to treat endometriosis in this area is more difficult because it lies close to the bowel. Other treatment options include a Mirena IUD, or a progesterone medication. If dyspareunia persists after all your endometriosis has been successfully removed, then there may be another cause for the pain.
Pain felt when opening bowels
The bowel lies in close proximity to the uterus, fallopian tubes and ovaries. The bowel is also a fairly frequent location for endometriosis. It is therefore not surprising that many women with endometriosis experience bowel problems, particularly with their period. Working out how much of the problem is due to endometriosis and how much is due to the bowel (in particular how many of the symptoms are due to irritable bowel syndrome –IBS) can be difficult.
Endometriosis that is located close to the bowel can be tricky to remove surgically. It may also be difficult to visualise during a pelvic laparoscopy because it can hide below the surface of the peritoneum. Sometimes it is easier to see (or feel) as a lump (nodule) in the back wall of the vagina. Most women who have endometriosis in this area will have low back (lumbar) pain, bowel pain and dyspareunia.
If bleeding from the bowel takes place at period time it is more likely to be due to extra blood vessels within the bowel wall rather than secondary to endometriosis that has spread through the bowel wall. The bleeding may also be due to other medical conditions such as haemorrhoids (piles), bowel disease or bowel cancer. If bleeding is experienced from the bowel, then you should consult you GP or family doctor without delay.
Intermenstrual Bleeding – bleeding between periods
Intermenstrual bleeding is common in women with endometriosis, but it is not known why this is. Gynaecologists speculate that it is because the lesions of endometriosis produce hormones and chemicals. If there is only a tiny amount of bleeding it is referred to as spotting.
If you have bleeding between periods, then this is a symptom that requires assessment and investigation to exclude serious causes. The causes of intermenstrual bleeding include: the contraceptive pill, an unexpected pregnancy, cervical polyps, and rarely it can be a symptom of cancer of the cervix or uterus. If you experience bleeding between periods consult your family doctor or GP who will examine your cervix, take a cervical smear and may arrange an ultrasound scan to check the lining of the uterus. The GP may make a referral to a gynaecologist for an assessment and endometrial biopsy.
If the intermenstrual bleeding is due to endometriosis, then it is more likely to happen in the week leading up to a period, rather than in the week following a period. Sometimes women will try different contraceptive pills, only to discover subsequently that the cause of the bleeding was endometriosis and not the pill. When the endometriosis is treated, the spotting usually goes away.
Endometriosis may make it harder for a woman to fall pregnant. Infertility is more of a problem if the endometriosis is severe. Having endometriosis does not mean that it is not possible to fall pregnant, but it does make it harder. Many women with endometriosis fall pregnant easily, but other women with endometriosis have major problems with infertility. Becoming pregnant is a complex process and endometriosis is one factor that is not in a woman’s favour. There are many other factors involved and if everything else is normal then becoming pregnant may not be a problem. These other factors include the woman’s age, whether or not she is ovulating each month, whether her fallopian tubes are patent and on the quality of the man’s sperm.
Gynaecologists note that most couples who having infertility problems have either severe endometriosis present, or other problems apart from the endometriosis.
Possible factors that lead to infertility may include irregular periods with infrequent ovulation or a low sperm count. When there are two milder problems present then falling pregnant becomes much more difficult. However, couples who have a mixture of fertility problems are able to become pregnant some times.
Pain or bleeding when passing urine
Pain passing urine is known as dysuria and is usually due to a problem with the bladder or urethra rather than endometriosis. For example the most common causes of dysuria are a bladder or urinary tract infection or frequency dysuria syndrome. If you experience dysuria then you should consult your family doctor or GP. If dysuria is frequent or troublesome then it needs investigating by a urologist initially.
If there are other symptoms present or other reasons to think that endometriosis is a possibility then an assessment by a gynaecologist is required as well.
Endometriosis can be associated with a condition known as interstitial cystitis. Occasionally endometriosis can grow on the inside of the bladder. If this happens then it can result in bleeding and the symptom of blood in the urine (haematuria).
It is not known why endometriosis can lead to tiredness, but it may be due to the hormones produced, the chemicals produced, the inflammation in the pelvis, the chronic pain if pain is a symptom or due to the irregular menstrual bleeding. Chronic pain is tiring, so is the stress and worry of being unwell, or trying to carry on a normal life with frequent pain.
Rarely endometriosis can occur in unusual locations and can lead to a variety of symptoms. To give some examples:
- If endometriosis affects the diaphragm then it may lead to pain just below the ribs, which is worse on breathing in and only present at the time of a period. This is rare.
- Pain in one point of a previous caesarean section scar that is worse with periods may be due to endometriosis in the caesarean section scar.
- Pain down the back of the leg due to sciatica that occurs only during periods, may be due to endometriosis affecting the sciatic nerve. This is extremely rare.
- A lump in the umbilicus (navel) that is tender or painful at the time of a period may be due to endometriosis of the umbilicus. This is rare.
Thoracic endometriosis is rare but does occur; read about thoacic endometriosis in detail here (technical article):