Technical difficulties in fetal skin sampling.

Attempts were made to obtain skin biopsies from the fetuses of 18 women in the 16th to 21st week of gestation. In four of them the purpose was prenatal diagnosis because of the risk that the fetus might be affected with a severe skin disorder; the remaining women were to undergo elective abortion by hysterotomy. In the first 13 cases the conventional "blind" biopsy procedure was used. Of 71 biopsy specimens obtained with this technique, only one out of every three consisted of skin; the remainder comprised fetal membranes, myometrium, or trophoblast. In one of the diagnostic cases where the "blind" procedure was used, inadvertent removal of tissue specimens from the amniotic sac was probably responsible for the intermittent leakage of amniotic fluid that occurred in this woman from the 26th week of gestation and for the premature delivery in the 33rd week. In the remaining five women (including one for diagnosis), a two-cannula procedure was employed (one cannula for the optic instrument and the other for the biopsy forceps), permitting biopsy of the skin under direct vision. All the biopsy specimens taken by this method consisted of skin.