Decidual vascular patterns in first-trimester abortions

In many cases of early spontaneous abortion (ESA), no reasonable etiology can be documented. However, some of these cases show abnormal decidual vessels that could be overlooked when examined on hematoxylin and eosin (H&E) slides alone. Diagnostic accuracy could be improved by the use of a limited histochemical (HC) and immunohistochemical (IHC) panel. We reviewed 1,095 ESAs, selecting 176 cases with abnormal decidual vessels and subclassifying them into three groups on the basis of decidual vascular pattern. Various HC and IHC stainings were performed in order to assess their use in improving diagnostic sensitivity. Histological findings on H&E were recorded and compared to the results obtained with HC and IHC. A variable role in the improvement of morphologic details was demonstrated for all three tested HC stainings (periodic acid-Schiff, Masson's trichrome, Weigert's stain for fibrin) and for two of the IHC markers (smooth muscle actin, human placental lactogen). In many cases of ESA, only compatibility diagnoses can be formulated. However, using a limited panel of HC and IHC stainings, some significant findings can be more reliably reported, allowing the pathologist to acquire confidence in his routine diagnostic work.