The diagnostic accuracy of outpatient miniature hysteroscopy in predictingpremalignant and malignant endometrial lesions

Objective To determine the accuracy of outpatient miniature hysteroscopy in the diagnosis of premalignant and malignant endometrial lesions. Design A prospective cohort study (1996-1997). Setting Minimal access surgical training centre in a large teaching hospita l. Methods Outpatient hysteroscopy and endometrial sampling was carried out on 248 patients with abnormal uterine bleeding. Any patients unable to underg o these outpatient procedures were admitted for a formal inpatient hysteros copy and curettage. Test performance characteristics were computed for hyst eroscopy, comparing its findings with the histological diagnosis which serv ed as a 'gold standard'. Main outcome measures The estimate of the accuracy of the hysteroscopic fin dings was based, for binary results, on sensitivity specificity and predict ive values. For multilevel results, the diagnostic accuracy was computed us ing likelihood ratios (LRs). With a normal hysteroscopy result, an LR of <1 indicated a decreased probability that a premalignant/malignant lesion was present, whereas with an abnormal hysteroscopy result, an LR of >1 indicat ed an increased probability that such a lesion was present. Results Hysteroscopy revealed features of normal endometrium in 228 women, of whom 12 were found histologically to have premalignant hyperplasia/cance r. Hysteroscopic features of premalignant/malignant endometrial lesions wer e suspected in 20 patients but the diagnosis was confirmed histologically i n six cases only This amounted to a sensitivity of 33.3% (95% confidence in tervals (CI) 14.4-58.8), a specificity of 93.9% (95% CI 89.8-96.5), a posit ive predictive value of 30.3%. (95% CI 12.8-54.3), and a negative predictiv e value of 94.7%. (95% CI 90,8-97.1). Analysis using likelihood ratios reve aled that for a normal hysteroscopy the LR was 0.7 (95% CI 0.5-0.9). The LR was 1.9 (95% CI 0.5-6.6) when there was intermediate abnormality (increase d endometrial thickness, abnormal vascularization, polypoid formations, mam illations and cerebroid irregularities). The LR was 51.1 (95% CI 7.9-326.9) when there was definite hysteroscopic abnormality (intermediate abnormalit y features associated with irregular polylobular friable excrescences with necrosis or bleeding). Conclusion The probability of the presence of a premalignant/malignant lesi on is not particularly altered by the finding of normal hysteroscopic appea rances or of intermediately abnormal features. However; if the hysteroscopi c findings are definitely abnormal, the probability of there being a premal ignant/malignant lesion is substantially increased. Normal findings at hyst eroscopy are not conclusive and do not eliminate the need for endometrial s ampling as they are not a substitute for benign findings on histological in vestigation.