Transcervical chorionic villi sampling: a comparison between the silver cannula and the Portex catheter

The Portex catheter and the silver cannula are two of the most widely used biopsy devices for chorionic villus sampling. In a prospective randomized study we used these two devices alternatively in 168 women. Significantly more trophoblastic tissue was obtained with the silver cannula than with the Portex catheter (p less than 0.05) while significantly more failures to obtain villus tissue were recorded with the Portex cannula (8/84 with the silver cannula vs. 19/84 with the Portex cannula; p less than 0.05). In 27 cases where use of the device met with failure to obtain chorionic villi after three attempts the other instrument was then used in the same patient (combined group). Four pregnancies aborted spontaneously after the procedure (2.4%). Significantly more complications occurred in the 'combined' group (4/27 vs. 4/168, p less than 0.05). A higher yield of trophoblastic tissue is possible with the silver cannula than with the Portex catheter.