"Blind" versus direct vision technique for fetal skin sampling in cases for prenatal diagnosis

Seven fetuses at risk of developing a serious inherited skin disorder (epidermolysis bullosa atrophicans generalisata gravis in 4, bullous ichthyosiform erythroderma in 2, and non-bullous ichthyosiform erythroderma in 1) were subjected to prenatal diagnosis by fetal skin sampling. The conventional "blind" biopsy procedure was used in the first 3 cases; a two-cannula technique (one cannula for the optic instrument and the other for the biopsy forceps) that permits biopsy of the skin under direct vision, was employed in the remaining 4 cases. With the "blind" technique, 8 to 10 biopsy specimens had to be taken to ensure that enough skin material would be available for the microscopic examination; only one specimen out of every two was found to consist of skin; the remainder comprised fetal membranes, myometrium, or tro-phoblast. In one case where the "blind" procedure had been used, leakage of amniotic fluid occurred and labor started in the 33rd week. With the two-cannula technique, the number of biopsy samples could be confined to two or three, and all proved to be of skin.