Observations of fetal heart rate characteristics related to external cephalic version and tocolysis.
External cephalic version performed in conjunction with tocolysis in the term breech presentation has been found to decrease the number of breech presentations at delivery and thus reduce the number of cesarean sections for breech presentation. However, information regarding the fetal heart rate (FHR) patterns associated with version is limited. In an attempt to broaden our understanding of the FHR changes that occur in association with version, the FHR tracings of 141 patients who had undergone version were analyzed. Approximately 39% of the fetuses exhibited changes in FHR characteristics during and/or after attempted version. These FHR changes were primarily manifested as bradycardias and/or decelerations. However, some of the fetuses (less than 5%) demonstrated a tachycardia or sine wave pattern. All of these FHR changes were transient and bore no apparent relationship to the subsequent outcome of the fetus. In addition to these FHR alterations, the incidence of diminished FHR variability (less than or equal to 5 bpm) was significantly higher after version than before version (p less than 0.01). The decline in FHR variability lasted 15 +/- 12 minutes. While this decline in variability appeared to be related to the success or failure of the version, the decreased variability observed after version was found to be unrelated to the tocolytic agent used and to the subsequent fetal outcome. In summary, alterations in FHR activity were frequent during the version process. All were transient and most responded to cessation of manipulation. Subsequent fetal outcome was apparently unrelated to the observed FHR alterations. Nonetheless, continuous fetal monitoring during and after the version is recommended.
D001946:Breech Presentation; D036861:Delivery, Obstetric; D005260:Female; D005318:Fetal Heart / Q000502:physiology*; D005323:Fetal Monitoring; D006339:Heart Rate; D006801:Humans; D007231:Infant, Newborn; D007746:Labor Presentation; D007752:Obstetric Labor, Premature / Q000517:prevention & control*; D011247:Pregnancy; D014463:Ultrasonography; D014710:Version, Fetal