Transabdominal chorionic villus sampling: A modified freehand ultrasonographically guided technique Lyndon M. Hill, MD, and Steven A. Laifer, MD Pittsburgh, Pennsylvania A simple modification of the technique of transabdominal chorionic villus sampling is described. This technique uses a short piece of extension tubing between the needle hub and aspirating syringe. The advantages of this technique are discussed. (AM J OasTET GVNECOL 1992;166:512.)
Key words: Chorionic villus sampling, ultrasonography
Transabdominal chorionic villus sampling is an effective method for prenatal diagnosis, allowing adequate sampling in >90% of cases.' In the typical twoperson technique, an assistant performs the ultrasono graphic examination. The primary operator inserts the biopsy needle into the placenta, connects a 20 ml syringe to the needle hub, and then aspirates during a slow, backward-and-forward movement of the needle tip! However, the sudden aspiration that is required for tissue sampling may alter the position of the needle in the placenta. Furthermore, redirection of the needle during aspiration is cumbersome and does not readily permit fine needle placement. A modification of the transabdominal villus sampling technique allows the operator to concentrate on needle placement, while the assistant's primary responsibility is aspiration. Method
Simultaneous ultrasonographic imaging is performed with a 3.5 MHz curvilinear transducer (General From the Department of Obstetrics and Gynecology, Magee-Womens Hospital, University of Pittsburgh. Received for publication August 9, 1991,. accepted August 15, 1991. Reprint requests: Lyndon M. Hill, MD, Department of Ultrasound, 300 Halket St., Pittsburgh, PA 15213. 611133387
Electric model RT3200; General Electric, Milwaukee). A 15 cm rather than a 9 cm sampling needle provides the operator with sufficient needle length to obtain a villus sampling in nearly every patient. Before the procedure is started, a 20 ml syringe containing 3 ml of transport medium is attached to a short piece of extension tubing (0.5 ml dead space) (Fig. 1). Once the operator has inserted the needle into the placenta, the stylet is withdrawn and the distal end of the extension tubing is attached to the needle hub. Repeated rapid aspiration of the plunger is applied by an assistant to obtain a chorionic villus sample. The extension tubing removes the assistant from direct contact with the needle. The operator can therefore concentrate on the important tasks of scanning and needle localization. Continuous monitoring of the needle tip helps to avoid inadvertent amniotic membrane penetration.
REFERENCES I. Brambati B, Lanzani A, Oldrini A. Transabdominal chorionic villus sampling: clinical experience of 1159 cases. Pre nat Diagn 1988; 8: 609-17. 2. Brambati B, Oldrini A, Lanzani A. Transabdominal chorionic villus sampling: a freehand ultrasound-guided technique. AM] OBSTET GVNECOL 1987;157:134-7.
Fig.!. Short piece of extension tubing (0.5 ml) is attached to syringe containing transport medium before chorionic villus sampling.
512
Key words: Chorionic villus sampling, ultrasonography
Transabdominal chorionic villus sampling is an effective method for prenatal diagnosis, allowing adequate sampling in >90% of cases.' In the typical twoperson technique, an assistant performs the ultrasono graphic examination. The primary operator inserts the biopsy needle into the placenta, connects a 20 ml syringe to the needle hub, and then aspirates during a slow, backward-and-forward movement of the needle tip! However, the sudden aspiration that is required for tissue sampling may alter the position of the needle in the placenta. Furthermore, redirection of the needle during aspiration is cumbersome and does not readily permit fine needle placement. A modification of the transabdominal villus sampling technique allows the operator to concentrate on needle placement, while the assistant's primary responsibility is aspiration. Method
Simultaneous ultrasonographic imaging is performed with a 3.5 MHz curvilinear transducer (General From the Department of Obstetrics and Gynecology, Magee-Womens Hospital, University of Pittsburgh. Received for publication August 9, 1991,. accepted August 15, 1991. Reprint requests: Lyndon M. Hill, MD, Department of Ultrasound, 300 Halket St., Pittsburgh, PA 15213. 611133387
Electric model RT3200; General Electric, Milwaukee). A 15 cm rather than a 9 cm sampling needle provides the operator with sufficient needle length to obtain a villus sampling in nearly every patient. Before the procedure is started, a 20 ml syringe containing 3 ml of transport medium is attached to a short piece of extension tubing (0.5 ml dead space) (Fig. 1). Once the operator has inserted the needle into the placenta, the stylet is withdrawn and the distal end of the extension tubing is attached to the needle hub. Repeated rapid aspiration of the plunger is applied by an assistant to obtain a chorionic villus sample. The extension tubing removes the assistant from direct contact with the needle. The operator can therefore concentrate on the important tasks of scanning and needle localization. Continuous monitoring of the needle tip helps to avoid inadvertent amniotic membrane penetration.
REFERENCES I. Brambati B, Lanzani A, Oldrini A. Transabdominal chorionic villus sampling: clinical experience of 1159 cases. Pre nat Diagn 1988; 8: 609-17. 2. Brambati B, Oldrini A, Lanzani A. Transabdominal chorionic villus sampling: a freehand ultrasound-guided technique. AM] OBSTET GVNECOL 1987;157:134-7.
Fig.!. Short piece of extension tubing (0.5 ml) is attached to syringe containing transport medium before chorionic villus sampling.
512
