Sister chromatid exchanges in first-trimester chorionic villi afterin vivo andin vitro exposure to diagnostic ultrasound

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Abstract
A study was done to evaluate the effects of diagnostic ultrasound on sister chromatid exchange (SCE) in first‐trimester chorionic villi under controlled technical conditions. Chromosome analysis was performed by the direct method using spontaneous mitoses from the cytotrophoblast layer, and SCE visualization was accomplished by a 72 h treatment with 5‐bromodeoxyuridine (BrdU) at a concentration of 10μg/ml. The slides were stained with ac ridine orange. Immediately before first‐trimester chorionic villus sampling, a group of ten pregnant women was exposed to diagnostic ultrasound for 20min (in vivo exposure). This group of patients was compared with a control group who were not exposed. A mean value of SCE/cell frequency of 4·2 ± 0·2 was found in the exposed pregnancies, while a value of 3·7 ± 0·2 was observed in the control group. After in vitro exposure of chorionic villi obtained from elective abortions, the frequency of SCE/cell did not differ significantly among samples with different exposures (1,2, and 3 h) and controls. The positive control (mitomycin C) yielded a significant increase in SCE frequency.