Chorionic Villi Sampling in a High-Risk Population Using the Portex Cannula

Abstract

The development of DNA analysis for fetal diagnosis, particularly of the haemoglobinopathics (Williamson et al. 1981) provided the incentive to develop a method for obtaining chorionic villous material early in pregnancy. The idea was not new, as others (Kullander and Sandhal 1973; Hahnemann 1974) had presented their experience in both experimental and diagnostic cases. The more recent report from Russia (Kazy et al. 1982), where both visualisation and biopsy forceps had been used under ultrasound guidance, was encouraging, but we were impressed by the Chinese experience (Dept. of Obstetrics and Gynecology, Tietung Hospital 1975) in which a third method, that of transcervical sampling, had been used with a low complication rate. Because our interest was in the haemoglobinopathics, we were anxious to develop a simple, reliable and inexpensive method applicable in the developing countries. Since 1974, fetal blood sampling has been performed at University College Hospital in patients at risk of a haemoglobinopathy (Fairweather et al. 1980; Ward et al. 1981). Despite improvements and increased experience fetal blood sampling at fetoscopy carries a significant obstetric risk (Kanokpongsukdi et al. 1985) and is associated with considerable emotional and physical trauma, particular in the 25% of patients for whom late therapeutic abortion is indicated. A first trimester diagnostic technique in such a high-risk population would have many advantages:

• 1. Permits “privacy” as the pregnancy is not obvious

• 2. Reduces time delay for diagnosis

• 3. Reduces social and emotional stress

• 4. Allows safer earlier therapeutic abortion of all these advantages, the single one of greatest benefit to the patient would be avoidance of second trimester therapeutic abortion.