Characterising pelvic masses using ultrasound.

The evaluation of a pelvic mass, detected at routine ultrasound or in the context of having acute symptoms, requires certain methodical steps. It is necessary to diagnose the primary site or origin of the lesion; understand whether the lesion is an intra- or an extra-peritoneal lesion; distinguish whether the structure of interest is 'functional' and transitory or if we are dealing with a persistent mass; attempt to discriminate between the benign or malignant nature of the lesion; formulate a specific diagnosis; and furthermore, in the case of a possible malignant mass, define the stage of the disease process. Transvaginal ultrasonography is a dynamic and interactive examination and besides an analysis of the echostructure, and 'elasticity' of a pelvic mass, it also permits an assessment of site-specific pain in different pelvic areas, and an evaluation of the movement of the mass in relation to adjacent structures. All these 'dynamic' features, together with morphological and vascular parameters, are essential for making a correct diagnosis. The features of acute ovarian pathology including torsion are not discussed in detail here. This article will concentrate on the characterisation of pelvic masses that may be encountered by any examiner in the course of an assessment of the female pelvis.