Fetoscopy guided by real-time ultrasound for pure fetal blood samples, fetal skin samples, and examination of the fetus in utero.

Techniques for sampling pure fetal blood, fetal skin and for fetal examination by fetoscopy are described in detail after experience gained in 151 diagnostic fetoscopies on 145 patients. Of particular importance were a real-time scanner and a particle size analyser. The region of insertion of the umbilical cord into the placenta was the optimum site for obtaining pure fetal blood, and this was achieved in 136 out of 143 patients (95 per cent) sampled at 18 to 23 weeks gestation. This made maternal blood transfusion before prenatal diagnosis of haemoglobinopathies unnecessary. An anterior placenta rarely prevented successful fetoscopy, and often made fetal blood sampling easier. Four fetal losses (3.7 per cent) were judged to be due to fetoscopy.