Evaluation of the feasibility of a new method for performing chorion villus sampling. Transcervical chorionic villi sampling: a comparison between the silver cannula and the Portex catheter. A randomized study to assess two different techniques of aspiration while performing transabdominal chorionic villus sampling. A randomised controlled trial of biopsy forceps and cannula aspiration for transcervical chorionic villus sampling. A randomized study of three cannulas for transcervical chorionic villus sampling.
This study aimed to evaluate the usefulness and safety of a new method for taking a placental biopsy.
                The procedures were performed using the traditional single needle technique (group 1) or the new method (group 2). In group 2, the piston was fixed in a simple metallic clip and the negative pressure was maintained in a continuous manner which was controlled with a three-way stopcock.
                Multiple uterine insertion was necessary in 14 cases (32.6%) in group 1 and five (11.9%) in group 2 (p < 0.05). The amount of chorionic tissue obtained was significantly higher in group 2 (19.1 +/- 15.0 mg vs. 33.9 +/- 17.4 mg p < 0.05). The abortion rates did not differ in either group.
                While using this technique, the operator is capable of performing the procedure without any assistance and of applying constant negative pressure only in the placenta. The advantageous outcomes are probably related to the size as well as the incessant fashion of the vacuum force. 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. The technique used to perform transabdominal chorionic villus sampling (CVS) is not standardized, but aspiration of villi is generally obtained by discontinuous vacuum created in a syringe, manually or by a hand-grip device. We evaluated the feasibility of a new method of performing CVS which employs a 4-mL Vacutainer connected to the needle, producing a continuous negative pressure.
                Two hundred pregnant women, whose gestational age ranged from 10 + 2 to 16 + 2 (mean, 12 + 1) weeks, entered the randomized study, which was powered to detect with 90% probability the absence of any difference in the size of chorionic samples obtained by using a 20-mL syringe with the vacuum obtained by a hand-grip device (Group 1) or by a vacutainer (Group 2). Four operators with different levels of experience performed all the procedures, which were done transabdominally using a freehand technique with a 20-gauge needle under ultrasound guidance.
                Maternal age, body mass index, gestational age and the way the needle was inserted within the chorion were similar in the two groups. The median amount of villi sampled was 20 mg, with no differences between the two groups. The rate of fetal loss was 1.7%. All losses occurred in women of Group 1 who had only one needle insertion. A second needle insertion was required more frequently while using the vacutainer.
                This new technique for performing transabdominal CVS uses a readily available device and is as effective as traditional sampling systems to aspirate villi. It has the advantage of being a one-operator procedure. This trial compared two instruments for transcervical chorionic villus sampling (CVS).
                Randomised controlled trial.
                Regional university prenatal diagnosis and treatment centre.
                Two hundred women were randomised at 10(+0)-12(+6) weeks of gestation to transcervical CVS using cannula aspiration (CA) or biopsy forceps (BF).
                Women undergoing indicated CVS signed informed consent. Randomisation after decision to perform transcervical CVS.
                Primary outcome: the rise in maternal serum alpha-fetoprotein (alpha-FP). Secondary outcomes: (i) placental trauma (fetomaternal haemorrhage [FMH]); (ii) laboratory, procedure, and cytogenetic results and pregnancy outcomes; (iii) patient and operator satisfaction; and (iv) economic analyses. Analyses were performed by intention to treat.
                The -FP rise did not differ between groups; there was no other evidence of placental trauma. BF were better tolerated by women, provided culturable tissue, after fewer instrument passes, with greater ease and in less time. BF were associated with cost savings.
                Unlike -FP, other markers of FMH were unaltered, questioning the reliability of alpha-FP as an indicator of FMH. Compared with CA, transcervical BF caused comparable placental trauma, appeared to be similarly effective and safe and were preferred by operators and patients. A randomized trial involving 200 transcervical chorionic villus samples taken with three different cannulas was undertaken. In terms of karyotype recovery and ease of insertion the aluminum cannula performed best although the placental site influenced the ability to recover villi for all cannulas.
For transcervical CVS, although there is some evidence to support the use of small forceps instead of cannulae, the evidence is not strong enough to support change in practice for clinicians who have become familiar with a particular technique. For transabdominal CVS, based on current evidence, there is no difference in clinically important outcomes with the use of a continuous compared with a discontinuous negative pressure needle aspiration system.