Ultrasound is the first imaging test used in most patients with an adnexal mass, and the great majority of adnexal masses are benign. Ultrasound has been shown to have a high sensitivity for detecting malignancy, but this is countered by a much lower specificity. In this chapter the ultrasonic features which suggest a malignant diagnosis and the wide differential diagnosis which often has to be considered are summarised. The performance of ultrasound in detecting malignancy in adnexal masses and its role in the diagnosis of ovarian cancer are then discussed.

Ultrasonic Technique

The patient's clinical presentation, age, menstrual status and CA125 level are all important factors influencing the differential diagnosis when the ultrasonic assessment is made.

Morphological Assessment

Most adnexal masses are assessed transvaginally because the resolution which can be obtained with high frequency transvaginal transducers (6–10 MHz) is superior to that obtained transabdominally, scanning at frequencies of 3–5 MHz. Transvaginal ultrasound is limited by a maximum depth of view of 5–6 cm and this makes it unsuitable for full examination of larger masses which have to be evaluated transabdominally. However, even when the mass is large, it is often worth doing a transvaginal examination because this allows high resolution visualisation of the inferior part of the mass and because it may be the only way to identify normal pelvic structures displaced by a large mass.