Ultrasound diagnosis
What can the ultrasound diagnose?
The difference between superficial endometriosis and deep infiltrating endometriosis is described in detail in the endometriosis section of this website.
Superficial lesions of endometriosis can never be diagnosed on ultrasound as they have no real mass, only colour, which can not be detected with ultrasound. The lesions look like brown small 'blood splatters' which are implanted on various areas in the pelvis. These lesions can only 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. The image on the left shows a normal pelvis. The image on the right shows a superficial endometriosis deposit.
Deep infiltrating endometriosis causes usually more destruction of the normal anatomy. Because lesions of endometriosis infiltrate into ligaments, bowel and bladder, adhesions can occur between organs such as the bowel and the uterus or the uterus and the ovaries. Both images below show deep infiltrating endometriosis with significant adhesions. Organs are stuck together.
Often when deep infiltrating endometriosis is unexpectedly found at laparoscopy, 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 this is 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. The left image shows a small lesion on the back of the vagina, causing pain with sexual intercourse. The right image shows a large bowel lesion, which seems very easy to see, but unless the bowel is inspected, it is not noticed on routine pelvic ultrasound.
In summary, because the superficial type of endometriosis can not be diagnosed with ultrasound, a laparoscopy may still be required to rule out endometriosis with certainty if symptoms are significant. But if the ultrasound was normal, there is a good chance that even if endometriosis is found at laparoscopy, it will be possible to complete the removal of most lesions. DIE can rarely be removed at first surgery, unless its presence was known preoperatively.
How is the ultrasound performed?
A normal transvaginal ultrasound will be performed. Some patients are told that the scan is done transrectally but this is not the case.
The ultrasound usually takes 30 minutes. The result are often discussed with you and will be sent to your referring doctor.
In some instances a sonovaginography
will be performed. This means that during the ultrasound 10-20ml of
gel is inserted in the vagina. This gel fills the top of the vagina
and provides an acoustic window which may allow better
visualisation of the area behind the uterus (pouch of Douglas),
which is the area of the pelvis most commonly affected by
endometriosis. The insertion of gel is not uncomfortable. No special
preparation is required.
Because endometriosis can infiltrate 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. For this reason some doctors prefer you to do a mild bowel preparation prior to the ultrasound when you have had a past history of severe endometriosis or when you have 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 on the right. If you don't have a proven history of significant endometriosis, or no significant bowel symptoms, it is probably not necessary to take bowel preparation.
Because not all doctors need you to take the mild bowel preparation, it is best to check with the ultrasound practice where you will be having the ultrasound when making your appointment.
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