The DopFet system: A new ultrasonic Doppler system for monitoring and characterization of fetal movement

To enable the investigation of fetal movement in a manner similar to fetal heart rate (FHR) monitoring we have developed an apparatus (the DopFet syst em) that consists of a pair of miniature sensors, a 2-MHz continuous-wave d irectional Doppler electronic module and a laptop personal computer. One of the sensors is aimed at the fetal limbs and the other at the thorax to det ect heart and upper body movements. The signals are analyzed, presented in real-time and postprocessed by software developed by us. The postprocessing software computes a number of parameters (the DopFet parameters) describin g fetal movement. These parameters can be divided into two categories: para meters that describe the quantity of fetal movement (i.e., number of moveme nts) and parameters that describe qualitative aspects of fetal movement (i. e., average movement duration). Future studies using the DopFet system will be aimed at discovering which of these parameters or combination of parame ters is the best indicator of fetal well-being. We present an example of a 0.5 h recording and the results of testing on 23 volunteer mothers. These r esults show good sensitivity of the system compared to real-time ultrasound (US), The system detects 96% of rolling movements, 100% of flexion movemen ts and 97% of leg movements. (C) 2000 World Federation for Ultrasound in Me dicine & Biology.