Endometriosis Assessment

Endometriosis is defined as the presence of normal tissue of the lining of the uterus (endometrium) in an abnormal place, usually the female pelvis. The most common sites in the pelvis are on and below the ovaries, and deep in the pelvis behind the uterus, called the Pouch of Douglas. Here the endometriosis grows on the ligaments behind the uterus and on the vagina and rectum. It also may grow on the bladder, appendix, and even sometimes in the upper abdomen or in the abdominal wall in scars of a laparoscopy or caesarean section.

Symptoms:

To make it confusing, some people with endometriosis have severe symptoms and others have very mild to sometimes hardly any symptoms. On the other hand, women who have the symptoms of endometriosis do not always have the disease.

Why Does It Occur?

While the exact cause of endometriosis is largely unknown, there are a few theories of what the cause may be. There are three theories.

Firstly, the “reverse menstruation” theory suggests that the lining tissue (endometrial cells) flows backwards through the fallopian tubes into the pelvis instead of exiting the uterus through the cervix and vagina. The endometrial cells can then implant in the pelvis, which gives rise to endometriosis lesions.

Secondly, the “direct transplantation” theory suggests that endometrial cells may directly attach to the walls within the abdomen and pelvis, or other parts of the body after surgery, such as cesarean section scars or abdominal wall scars.

Thirdly, the “genetic” theory suggests that some families may be more likely to be affected with endometriosis than others.

Different Forms

A distinction is made between superficial lesions and deep infiltrating endometriosis.

In the majority of women with endometriosis the lining of the uterus found in the pelvis has only implanted superficially. These lesions may present as raised black or brown lesions, white discolouration, red "flame-like" streaks, clear blisters, small red blisters, bluish lesions or yellow patches.

About 20% of women however will not just allow the lining cells to implant in the pelvis, but also to infiltrate mainly into bowel, bladder, the vagina and ligaments behind the uterus (uterosacral ligaments). This form of the disease is called deep infiltrating endometriosis (DIE). Deep infiltrating endometriosis causes usually more destruction of the normal anatomy and is generally significantly more difficult to treat. Because lesions of endometriosis infiltrate into ligaments, vagina, bowel and bladder, adhesions can occur between organs such as the bowel and the uterus or the uterus and the ovaries.

What Can The Ultrasound Diagnose?

Superficial lesions of endometriosis are challenging to diagnose on ultrasound as these lesions have no real mass. The lesions look like brown small 'blood splatters' which are implanted on various  areas in the pelvis. These lesions can be seen on laparoscopy. They are generally easy to remove. Special preoperative measures are rarely required. They can however cause as much or more pain than some deep infiltrating lesions. 

Deep infiltrating endometriosis causes usually more destruction of the normal anatomy. Because lesions of endometriosis infiltrate into ligaments, bowel and bladder, a little 'clump' or 'nodule' is formed, which does have mass and can be detected with ultrasound. Also the adhesions that can occur between organs such as the bowel and the uterus or the uterus and the ovaries can be seen with ultrasound. 

Often when deep infiltrating endometriosis is unexpectedly found at laparoscopy, without a preoperative diagnosis with ultrasound, the removal of endometriosis can not be completed as special preparation is required to allow removal of such lesions. The patient needs to take bowel preparation to allow surgery on the bowel, and often it is preferable to have a colorectal surgeon present at the surgery. If these lesions are diagnosed preoperatively, the necessary preparations can be made prior to starting the first laparoscopy and  repeat surgery can be avoided.

The larger the lesion, the easier it is to see on ultrasound, but in the hands of experienced imaging specialists lesions of only a few millimetres can be diagnosed. 

In Summary

An Ultrasound cannot completely rule out Endometriosis because the superficial type of Endometriosis can be extremely difficult to diagnose with Ultrasound. A Laparoscopy may still be required to rule out Endometriosis if symptoms are significant. But if the Ultrasound was normal, there is a good chance that even if Endometriosis is found during a Laparoscopy, it will be possible to complete the removal of most lesions. DIE on the other hand can rarely be removed at first surgery, unless its presence was known preoperatively. Because Ultrasound can diagnose these lesions, the surgery can be planned better and repeat surgery is less commonly necessary.

How Is The Ultrasound Performed?

A normal transvaginal ultrasound will be performed. Some patients are advised that the scan is routinely done transrectally but this is very rarely required.

The ultrasound usually takes between 15 and 30 minutes.  The result are often discussed with you and will be sent to your referring doctor.

Because endometriosis can involve the bowel, the doctor or sonographer who does the ultrasound will carefully look at the bowel during the transvaginal ultrasound. When the rectum is empty, the views of the bowel are generally better as bowel content can cause shadows on ultrasound. You may be asked to undertake a mild bowel preparation prior to the ultrasound to optimise the views when you have had a past history of severe endometriosis or when you have had significant bowel pain during your periods. This consists of a mild laxative the night before the ultrasound and an enema within an hour before the ultrasound as outlined below.

Bowel Preparation.

If you have been asked to have bowel preparation, please be assured that the bowel preparation is usually mild and well tolerated. It is outlined below. All the medication is over the counter medication. It is cheap and does not require a script. 

Make sure the chemist gives you the fleet enema rather than the oral fleet.  

The night before the scan take:

Dulcolax tablet, one tablet of 5mg or Dulcolax SP 10 drop. This is mild laxative that will make it easy to go to the toilet the next morning. Some people experience some cramping.

Just before the scan:

Use a Fleet enema: A fleet enema is a bottle with 133ml of liquid in it. It has a nozzle that is precovered with gel. Apply it while lying on your side, inserting the nozzle into the anus and squirting the full content of the bottle into the rectum. An urge to go to the toilet will follow application. Try to wait 3 to 5 minutes before going to the toilet.
After this your rectum should be completely empty, optimising Ultrasound images.