Ultrasound Evaluation of the Myometrium Using the MUSA Terminology, Comparison With Histology.

Primary aim: Diagnostic accuracy of the MUSA terms and definitions

Every patient planned for hysterectomy for myometrial pathology (e.g. benign fibroid, benign adenomyoma or malignant uterine sarcoma) will undergo a systematic preoperative ultrasound scan. Around 50 ultrasound characteristics will be assess as to diagnostic accuracy as predictors (Prospective evaluation of MUSA terms and definitions). The estimation for sarcomas is based on preliminary and unpublished results from an ongoing prospective study led by prof dr Antonia Testa from the Università Cattolica di Sacro Cuore Largo Agostino Gemelli in Rome showing an incidence of 4.9% for uterine sarcomas amongst women with a myometrial lesion referred to their tertiary center (Antonia Testa, personal communication).

Secondary aim: Development of prediction model

The Secondary aim is to build predictive models to differentiate between benign myometrial lesions (e.g. adenomyosis and fibroid) and malignant myometrial lesion (e.g. uterine sarcoma). Because of the small number of cases with malignant myometrial lesion (expected to be 5% of the study population or around 75 women), we will limit the number of variables to be tested in order to avoid overfitting. Based on current literature, we preselected following characteristics for development of a prediction model:

• Outer contour: regular of irregular
• Echogenicity of uterine lesion: uniform (homogeneous) or non-uniform (mixed)
• Colour score: 1 to 4
• Presence of central necrosis
• Maximal diameter of the lesion (in mm)
• Presence of acoustic shadows