The role of hexoprenaline in suprapubic amniocentesis during late pregnancy. A pilot study
Suprapubic amniocentesis is often complicated by the fetal head being fixed in the pelvis, oligohydramnios or a hyperirritable myometrium. These factors limit the success rate associated with the procedure. If the myometrium is relaxed with a β2-stimulant, a higher success rate may be achieved. This was investigated in a randomized, prospective, double-blind pilot study using hexoprenaline. When four- or five-fifths of the fetal head was palpable above the pelvis, hexoprenaline (17 amniocenteses) showed no advantage over a placebo (16 amniocenteses). However, when three-fifths or less of the fetal head was palpable above the brim, 4 dry taps were obtained in the control group using a placebo (17 amniocenteses), while none occurred in the study group (19 amniocenteses) (P < 0.05). Elevation of the fetal head was less difficult in the study group, but this difference was not statistically significant. These results suggest that hexoprenaline is not indicated for routine use during amniocentesis. When a dry tap is obtained or when marked difficulty is encountered in lifting the fetal head from the pelvis, 10 μg hexoprenaline administered intravenously 5 minutes before amniocentesis appears to facilitate successful completion of the procedure. However, a larger series is necessary to confirm this observation.