The influence of needle and syringe size on chorionic villus sampling of term placentae: a randomised trial

OBJECTIVE: To determine the effect of needle and syringe size on the amount of tissue obtained at chorionic villus sampling METHODS: Two needle sizes, 18 and 20 gauge, and two syringe sizes 5 mL and 20 mL, were used to assess samples from term post-partum placentae. Each of the four combinations was tested by 25 aspirations. The placentae were divided into 100 grid spaces and each grid space was randomly allocated to a needle/syringe combination. The resulting samples were cleaned to separate the chorionic villi (CV), centrifuged and then weighed. RESULTS: Significantly more tissue was obtained with an 18-g needle compared with a smaller 20-g needle (median weight difference 1.5 mg, 95% CI 0.8-2.3 mg). More tissue was also obtained with the larger 20-mL syringe though the impact of the syringe size was less than that of the needle size (median difference 0.8 mg, 95% CI 0-1.6). CONCLUSION: A larger syringe and needle size yields a larger quantity of chorionic villi from the post-partum term placenta.