Providing professional care in fertility, gynaecology and minimally invasive surgery


What is  endometriosis?

Endometriosis  refers to the presence of abnormal glands that normally line the uterus,  outside the uterine cavity. Typically this occurs in the pelvis but it may  occur in virtually any part of the body. The most common locations for  endometriosis are the outer surface of the ovaries, the pelvic peritoneum (the  tissue that lines the abdomen), the uterus, fallopian tubes, bowel or bladder.

How common is it?

Endometriosis is found in around 40% of women who are having difficulty conceiving and around 15% of the population.

Is all endometriosis the same?

Endometriosis most likely represents a diverse spectrum of disease, which affects different women in different ways. Some women may have quite severe endometriosis and are  virtually without symptoms whilst others have milder endometriosis and have  obvious symptoms or difficulty conceiving. There is a complex interaction between the endometriosis tissue and the woman’s body, which is not completely understood.

Why would I get endometriosis?

The following factors may increase your chance at developing endometriosis.

  1. No pregnancies resulting in the birth of a child.
  2. Endometriosis in a woman’s mother or sister.
  3. Short menstrual cycles (less than 27 days) with prolonged flow (more than 8 days).
  4. Partial or complete obstruction of normal menstrual flow, e.g., from uterine abnormalities such as a tight cervix, vaginal septum or uterine  fibroids.
  5. White or Asian race.

Conditions that decrease the amount or frequency of menstrual bleeding may lower the risk of  endometriosis, e.g., pregnancy or prolonged use of the oral contraceptive pill.

Causes  of endometriosis

The cause of endometriosis is not known.  However, several theories have been suggested:

  1. Retrograde menstruation is a theory proposed by Sampson in the  1920’s. It states that menstrual blood flow and tissue flows backwards through  the fallopian tubes into the pelvis. Retrograde menstruation is often observed  during a laparoscopy, when the woman has her period, however not all women  develop endometriosis. This means that there is a complex and incompletely  understood relationship between the endometriosis tissue and the woman’s  pelvis, which enables the disease to progress. However, endometriosis has been  observed after tubal ligation (clipping of the tubes) and so clearly retrograde  menstruation cannot be the entire answer. It is likely that subtle changes in  the immune system, or the endometriosis tissue’s ability to produce new blood  vessel growth, may be the factors involved in progression of endometriosis.
  2. Endometrial tissue from the uterus might be transported through  the blood or lymphatic vessels to distant sites within the pelvis. This explains how endometriosis can sometimes be found in sites that do not have any  close physical proximity to the uterus or fallopian tubes.
  3. Coelomic metaplasia is a concept that states that the cells lining the abdomen and surface of the ovaries may change, of their own accord,  into endometriosis tissue under the influence of certain factors, which may  include retrograde menstruation or infections.

Symptoms of endometriosis

Those with  endometriosis may have no signs or symptoms. In those who do have symptoms, the  intensity and location of the pain does not always correlate well with the  severity or location of the endometriosis. It is possible to have referred pain  from endometriosis, e.g., pain at a distant site.

For many women,  severe pelvic pain or pain during periods is their main symptom. The pain  typically occurs around the time of the period, during or after sex, with a  full bladder, on passing water or on using the bowels. Spotting between  periods, frequent or heavy menstrual flow and pain that does not respond to the  use of the contraceptive pill and simple analgesics are all strong indicators  of endometriosis. Pelvic pain is probably the result of bleeding from areas of  endometriosis within the pelvis and “inflammatory mediators” such as  prostaglandins and interleukins, which may also be implicated in difficulty  conceiving.

Endometriomas and Deep Infiltrative Endometriosis

Endometriomas are areas of endometriosis that are large enough to form a cyst on the ovaries. The  endometriosis cyst contains a brown liquid that has the appearance of melted  chocolate, hence the alternative name “chocolate cysts”. Chocolate cysts have a  characteristic appearance on ultrasound scan however unless cysts or very major  endometriosis is present, ultrasounds are not good at diagnosing endometriosis  as a general rule. Deep infiltrative  endometriosis (DIE) is a name given to endometriosis that has spread through  the lining of the pelvis or other tissues and is infiltrating the structures beneath such as the ligaments supporting the uterus, the bowel, bladder or other structures.

Diagnosis  of Endometriosis

There are  unfortunately no blood tests or imaging studies that can make a definite  diagnosis of endometriosis however this is done by laparoscopy and submission  of a sample of endometriosis to the pathology service. Endometriosis is rarely  diagnosed before a girl’s periods commence or after the menopause. Laparoscopy for  exploratory surgery is the definitive way of diagnosing endometriosis. Without  this, the diagnosis is only assumed.

Staging  of Endometriosis

Various staging  systems for endometriosis have been proposed. The most commonly used is the  American Society For Reproductive Medicine (ASRM) staging system, which is a  good descriptive method however does not correlate closely with the effect of  the endometriosis on a woman’s fertility. Stages are 1 to 4. There are also anomalies within the  scoring system (see image library) that means that you may have stage 4 disease  that doesn’t look very extensive.

Treatment  of endometriosis

There are several  treatment options for women with endometriosis and the kind of treatment  embarked upon depends purely on a woman’s wishes, her desire for fertility, the  desired effects and the wish or not to be on long-term medication.


I would consider  it unsatisfactory to use these as my first line treatment after a positive  diagnosis of endometriosis. Most women come to me having already tried the oral  contraceptive pill in combination with analgesics to free themselves from  pelvic pain. Once a diagnosis is made then an attempt should be made to cure  the endometriosis.

Oral Contraceptive Pill

The oral  contraceptive pill contains both oestrogen and progesterone. When taking the  pill for a while the effect on the lining of the uterus is generally to cause  it to think substantially which results in much lighter periods. However, it  never really disappears. The same effect occurs with endometriosis in that the  endometriosis is suppressed without ever really disappearing. Nonetheless, if  disease is mild, the oral contraceptive pill can be a useful and physiological  way of suppressing pain symptoms without causing any real harm. The therapy can  be continued for a long time, generally without side effects.

Other Forms of Hormonal Therapy

Other forms of  hormonal therapy similarly seek to suppress endometriosis. This would include  progesterone tablets, progesterone injections, Danazol or gonadotropin  releasing hormone analogues. None of these are without significant side effects  and none are generally taken for a long period of time for reasons of cost,  convenience and side effects.


In my hands, surgery is the mainstay of treatment for diagnosis and treatment of  endometriosis. Many treatment modalities have been described in the past and  all have their advantages and disadvantages. The exact type of surgery that is  required depends on the extent of a woman’s symptoms, her desire for fertility, the site and radiation of the pain and the potential risks and benefits of  surgery.

Excisional Surgery

Excisional  surgery refers to cutting out the deposits of endometriosis. This requires  greater time and skill and is ideally suited to those in whom the endometriosis  is severe, resulting in adhesions, sticking together of tissues and distortion  of anatomy. If the endometriosis is deep then excisional surgery is really the  only kind that can be carried out with the hope of obtaining adequate cure.

Ablative Treatment

Ablation refers  to burning or destroying endometriosis deposits. This can either be done with  electrical energy or laser. Laser treatment had a vogue in the 1980’ and 1990’s  however the technology is expensive, difficult to use and cumbersome. Ablative  therapy typically works best where lesions are small and superficial however in  the presence of deep disease, disease clearance is much less likely.

Other  Issues In Surgical Treatment

The vast majority  of endometriosis should be treated by laparoscopic approach. In rare cases  laparotomy (opening of the abdomen through a large incision) may be necessary  when dealing with extremely extensive adhesions or invasive endometriosis  involving the ureters, bladder or rectum. Indicating for removing endometriosis  on such structures really depends on a patient’s symptoms and plans for  fertility. Removal of deep, infiltrative endometriosis involving the bowel is  an extensive procedure requiring removal of a short section of bowel and often  has associated bowel disturbance thereafter for many months. Pain relief is  achieved in most patients who undergo laparoscopic resection of endometriosis  however the risk of recurrence is estimated to be up to 40% at ten years follow up and around 20% of patients may undergo additional  surgery within two years. Success rates in relieving pain are most marked in  those who have severe, e.g., stage IV disease and such women often feel a  reduction in pain in the immediate post-operative period.

Definitive Surgery

Definitive  surgery involves a hysterectomy with or without removal of the fallopian tubes  and ovaries. Removal of the ovaries in a pre-menopausal lady is a matter not to  be taken lightly however if they are heavily involved with endometriosis and  are likely to form adhesions resulting in ongoing pain or the requirement for  further surgery, then removal of the ovaries is sometimes required. The  decision to proceed to a hysterectomy is primarily dependent on the patient’s  interest in having (more) children.

Hormone replacement after hysterectomy for severe  endometriosis

If the ovaries  are removed in a premenopausal lady then oestrogen replacement with or without  progesterone to prevent menopausal symptoms and loss of bone density, should be  considered even if surgery has not removed all the endometriosis. There is a  very low likelihood of symptom recurrence in these cases (less than 5%) except if endometriosis involves the rectum. It is not known whether  the use of progesterone will reduce the chances of any residual endometriosis  growing again. This theoretical benefit of avoiding a small risk of recurrent  disease must be balanced against a small increase in the incidence of breast  cancer.

Reasons  for combination medical and surgical therapy

Pre-Operative Medical Therapy

Hormonal  suppression such as with GnRH analogues (Zoladex and others), has been used  prior to surgery to try to decrease the amount of adhesions and make the  endometriosis less biologically active (“sticky”) thereby facilitating the  surgery. However, there is no evidence that this results in a better operation  and in the vast majority of cases a competently performed primary operation  with attention to detail in clearance of disease, is far preferable.

Post-Operative Medical Therapy

Previously,  progesterone or tablets such as Danazol or GnRH analogues have been used in conjunction  with surgical clearance of disease in order to try to reduce disease  recurrence. If, after surgery a woman still has pain with periods then  certainly suppressing the menstrual cycle may be of benefit in reducing pain. However there is  no increased chance of pregnancy (obviously impossible whilst the periods are  stopped by tablets) and upon ceasing medical suppressive therapy, endometriosis  will recur. My own approach is that if the woman requires contraception or if  symptomatic relief has been incomplete after surgery, the most physiological  approach is to commence and remain on the oral contraceptive pill.  This is as good as more aggressive and  expensive medications.  There is evidence  that insertion of a Mirena IUCD gives an additional benefit to a well-performed  operation in terms of pain relief.

Endometriosis  and infertility

This is a very  complex subject and there is still much research being done on the matter. There is a complex relationship between endometriosis and infertility, which is  due to the differing biological behaviour of the disease and different  characteristics of patients. The mechanism for impaired fertility may involve  anatomical distortion of the fallopian tubes or other pelvic structures and the  production of chemicals substances, which create a hostile environment to  ovarian function, ovulation, fertilization and implantation. There is no  question that symptomatic endometriosis is best surgically treated prior to  embarking on infertility procedures. Some women will  fall pregnant when the endometriosis is removed however others may not.  Nonetheless, it is important to rule out simple potential causes of infertility  before embarking on an expensive and complicated treatment regimen such as IVF  even though success rates are often high. The exact nature and extent of  endometriosis clearance surgery must be tailored to a woman’s individual  requirements. In older subjects who already have impaired fertility and may  have extensive endometriosis on the ovaries, is currently thought (2009) that  the most expeditious way of achieving a pregnancy is to proceed straight to  IVF, although during the stimulation cycle extensive endometriosis may cause  significant pain and discomfort.

In general then I  recommend a thorough laparoscopic excision of all accessible endometriosis as  part of the plan for addressing the causes of infertility.  This will improve chances of falling  spontaneously pregnant and will also improve your chance of success with IVF.

Treatment  of Symptoms Related to Deep Infiltrative Endometriosis

Deep infiltrating  endometriosis is a term used to describe endometriosis that has invaded deep  structures such as the rectovaginal septum (space between the vagina and  bowel), bowel, ureters, bladder or other pelvic structures. If disease is  asymptomatic and merely noticed by doctor’s examination findings and fertility  is not an issue, then the disease may be managed expectantly. Medical therapy  of symptomatic patients is generally ineffective and only transient whereas  surgical therapy is effective for relieving pain, dyspareunia and pain with use  of bowels in many cases, however some studies suggest up to 40% recurrence of pain after eight years. Surgical resection of deep infiltrating  endometriosis does not necessarily enhance future pregnancy rates. As mentioned  above, if pregnancy is a primary goal, then proceeding straight to IVF is the  most expeditious way of achieving a pregnancy. If the disease is symptomatic  then the most effective current regimen may be surgical resection followed by  three months of GNRH analogues, followed by IVF.


Endometriosis can  be an enigmatic and difficult to treat condition. The mainstays of assessment  are careful history, detailed examination and ultrasound scan and a well performed  operation plus or minus post-operative medical therapy by the most simple and  physiological means possible. Treatment of endometriosis in the presence of  infertility must be tailored to a patient’s individual needs. Complete removal  of known endometriosis definitely enhances spontaneous pregnancy rates however  chasing more severe endometriosis that may involve operations with their  potential for prolonged recovery phases, may not necessarily be required before  embarking on fertility treatment. Pregnancy itself may improve the symptoms of  endometriosis but does not cure it. Pregnancy provides a similar hormonal  picture as remaining on the oral contraceptive pill and hence endometriosis is  suppressed but not removed. During pregnancy a women has no periods and so pain  from endometriosis may stop or be improved.

Questions to ask your doctor about endometriosis

I encourage you to be  very selective about whom you choose to operate on your endometriosis.  If you have endometriosis, have a family history endometriosis or think that you may have endometriosis due to your  symptoms it makes sense to see a doctor who treats endometriosis on a frequent  basis.

You should consider the following:

  • What treatment method does your doctor advise for endometriosis?
  • How do you measure the outcome of your treatment or surgery and for how long does your doctor follow their patients?
  • If the initial treatment is unsuccessful what does your doctor recommend as a subsequent course of treatment?
  • Does this treatment approach temporarily help your symptoms or actually remove the disease?
  • What proportion of patients get a second operation within a year?
  • Does your doctor recommend diathermy burning, excision or lasering of endometriosis and why?
  • Will the procedure be performed via laparoscope or laparotomy?
  • Will photos and videos be taken of your operation and be presented to you with an explanation after the procedure?
  • Will biopsies of all endometriosis specimens be taken and sent to pathology for verification?
  • If a hysterectomy is eventually needed will this be performed via laparoscopic or open approach?
  • What is your doctor’s specific training and ongoing interest in the endometriosis surgery?
  • If the endometriosis lies over the ureters or involves the bowel, will this be corrected?

The Image Gallery contains images of live operating and pathology, used with patients’ consent. It is intended to assist your doctor explain various aspects of gynaecological surgery and pathology, but may be viewed by the general public.