Diagnosing Abnormal Bleeding: Saline Infusion Sonography
By Frederick R. Jelovsek, M.D.
The diagnosis of abnormal menstrual bleeding is often a difficult one. Sometimes the basis is hormonal, other times it may be due to mechanical causes. These can be polyps, fibroids that impinge upon the endometrial cavity, or even a premalignant endometrial hyperplasia or cancer of the cervix or uterus. If it was known that the bleeding was caused by hormonal fluctuation, there would be no need for invasive procedures like a dilatation and currettage (D&C) or looking into the endometrial cavity (hysteroscopy). If it was known for sure that there was a mechanical cause for the bleeding, one could go straight to D&C and not waste months trying different hormone regimens to straighten out the abnormal bleeding.
Vaginal probe ultrasound was supposed to help in evaluating the endometrial cavity but it has disadvantages. Its not able to always pick up intrauterine abnormalities. Ultrasound is best as an imaging tool when there is a liquid/solid tissue interface. Unfortunately there are not always secretions in the endometrial cavity that would help outline polyps, fibroids, etc.
Enter a new technique called saline infusion sonography (SIS) in which saline is injected into the uterine cavity by a small catheter immediately prior to a vaginal probe u
ltrasound. The liquid helps create an interface with the lining of the uterus and abnormal structures can be seen on imaging. The technique is not that new, having started in 1981, but it has only become more frequently used in the middle 90's as scientific reports confirmed its effectiveness.
A recent article by Bradley and Andrews, Bradley LD, Andrews BJ: Saline infusion sonography for endometrial evaluation. The Female Patient 1998; (23):12-36, has outlined some of the times when this technique would be indicated:
- any abnormal uterine bleeding refractory to medical therapy
(usually in women under age 40 in which hormonal therapy has been initially tried)
- women with postmenopausal bleeding in which the uterine lining is greater than 5 mm
- irregular bleeding in women on menopausal hormone replacement therapy
(usually after the first 3 months of starting therapy)
- a thickened or bizarre appearance of the endomentrium in women receiving tamoxifen therapy for breast cancer
Vaginal ultrasound without the saline infusion is very good for finding ovarian pathology such as cysts or tumors or tubal pathology such as active pelvic infection and ectopic pregnancies. In the uterus, it can pick up large fibroids in the uterine muscle or cervical stenosis with fluid accumulation (a possible cancer sign). It can miss small fibroids that are encroaching upon the endometrial cavity and also polyps, hyperplasia and early cancers. Saline infusion sonography has been able to add:
|Tamoxifen induced changes|