The construction and utility of an amniocentesis trainer

Our goal was to design an inexpensive amniocentesis trainer for instruction and practice with ultrasonography-assisted needle guidance and the freehand technique.

The amniocentesis trainer was constructed from a commercially available 5.3-L storage box (No. 5805; Rubbermaid Incorporated, Wooster, Ohio). Sonodense sperical targets 2.3 cm in diameter were taped to the bottom, and the box was filled with a gelatin mixture. The box was covered with a rubber membrane from a pelviscopy trainer (United States Surgical Corp, Norwalk, Conn). After the gelatin mixture set overnight at 40 degreesF, the amniocentesis trainer was ready for use.

When a needle is introduced through the membrane into the gelatin, the ultrasonographic image is a reasonable simulation of an amniocentesis. The trainer improved the ability of an operator to perform a freehand amniocentesis, orient the ultrasound transducer, follow a needle with continuous ultrasonographic guidance, and hit a 2-cm target. The gelatin also allows for evaluation of improvement between amniocentesis attempts because a faint image of the needle track from prior attempts remains visible. Once basic amniocentesis skills are mastered, the trainer is easily modifiable so that obstacles can be added that could simulate umbilical cord and fetal extremities.

We were able to construct an inexpensive amniocentesis trainer that facilitates instruction in the freehand amniocentesis technique. This trainer enables an operator to master the skills necessary to perform the technique of freehand ultrasonography-guided amniocentesis under direct ultrasonographic visualization without putting a patient through the discomfort of participating in the learning curve.