Sonographic assessment of non-malignant ovarian cysts: does sonohistology exist?

BACKGROUND: Transvaginal ultrasound (TVU) is feasible and accurate in the differentiation between non-malignant and malignant ovarian abnormalities. However, despite the clinical relevance, the accuracy of TVU in the differentiation between the many different non-malignant cysts is unknown. METHODS: Between 1992 and 2002, all women who had surgery at our centre because of a non-malignant ovarian cyst were included prospectively in this study. The sonographic characteristics as well as the expected histological diagnosis (the 'sonohistological diagnosis') were evaluated pre-operatively. This diagnosis was compared with the histopathological diagnosis, and diagnostic parameters [with 95% confidence interval (CI)] of the sonohistological diagnosis were calculated. Logistic models, with the sonographic characteristics as variables, were constructed for each histopathological diagnosis. RESULTS: A total of 406 women were included consecutively. The overall diagnostic accuracy of the sonohistological diagnosis was 60% (95% CI 0.56-0.65). Only in cases of simple ovarian cysts did the diagnostic accuracy of the respective logistic model exceed that of the sonohistological diagnosis (0.88 versus 0.81, P < 0.01). The diagnostic accuracy of the sonohistological diagnosis for endometriotic and dermoid ovarian cysts was significantly better compared with the respective logistic model (0.84 versus 0.71, P < 0.01 and 0.87 versus 0.82, P = 0.03, respectively). CONCLUSION: In approximately half of the non-malignant ovarian cysts, TVU is capable of distinguishing between the different histopathological diagnoses of non-malignant ovarian masses. Only in the diagnosis of simple ovarian cysts might use of the logistic models be helpful.