Toluidine blue staining in the diagnosis of endometrial pathologies: a preliminary study before chromohysteroscopy

To assess the efficacy of toluidine blue (TBlue) staining in the detection of endometrial premalignant or malignant lesions in uterine specimens obtained from hysterectomies. We hoped that the results of this preliminary study would help us in our future studies which may be on chromohysteroscopy.

We developed an endometrium staining technique in which TBlue solution was used as a vital dye. The study enrolled 50 patients. Of these, 20 patients known to have a premalign or malign lesion of the uterus constituted the study group and 30 patients were recruited as the control group who were operated for leiomyoma of the uterus. Immediately after hysterectomy, all specimens were dyed with TBlue solution and a frozen section procedure was performed on the positively stained areas. The pre- and post-operative histopathological diagnoses of the participants were compared and the reliability of the new method was calculated.

The sensitivity of TBlue staining in the determination of endometrial pathologies was 100% (95%, CI 0.83-1) with a specificity of 90% (95%, CI 0.74-0.96). As a diagnostic test, the positive predictive value (PPV) was 87% with a negative predictive value (NPV) of 100%. The positive likelihood ratio (+LR) was 10 (95%, CI 3.41-29.2).

Our preliminary results demonstrated that TBlue staining of endometrium is a reliable and highly sensitive technique that may be used in the frozen section examination of uterine specimens if a malignancy is suspected. Moreover, TBlue staining of endometrium may prove useful in hysteroscopy, although the technique, interpretation, and indications require further studies.