Clinical experience with the latex and new estane balloons and a short and flexible guide is described. The extraovular balloon as an intrauterine pressure sensor is compared to the open-ended transcervical intraamniotic catheter, and the balloon is considered superior in many respects. The transcervical extraovular water-filled 0.8-ml estane balloon is recommended for use in place of the open-ended transcervical catheter in all clinical situations in obstetrics in which there is a need for monitoring intrauterine pressure.