Intrapartum fetal monitoring.
From the fetal viewpoint, labour is a prolonged contraction stress test which most pass without incident. Labour also represents the obstetrician's last opportunity to influence perinatal outcome and ensure that those fetuses who have suffered chronic hypoxia antenatally are recognized promptly, so that labour is supervised in a way that does not place them at increased risk of either death or birth asphyxia. In the case of the fetus who enters labour healthy, with normal reserves, labour is managed with the same aim in mind, but with the foreknowledge that visualization of a normal volume of clear amniotic fluid and reasonable duration of labour makes the development of hypoxia and asphyxia unlikely. Those at increased risk of hypoxia should be monitored electronically, but, for the remainder, intermittent auscultation is satisfactory until labour lasts in excess of 5 hours, or if the patient requires oxytocin, or if an epidural is placed. If EFM is used, then it is important to provide adequate education in trace interpretation, with particular emphasis on the importance of short-term variability. Widespread use of EFM has provided us with an immense amount of knowledge about fetal physiology, but it is critically important for the practising obstetrician to understand that, in the low-risk patient, EFM is not more effective than IA in preventing death from asphyxia, that EFM does protect against asphyxial seizures, but that widespread use of the technique has not been associated with a significant reduction in the population of permanently handicapped infants. This information is particularly relevant in developing nations where money spent on sophisticated monitoring equipment might be better spent in other areas. From the maternal point of view, intensive fetal monitoring has profound implications by virtue of its usual effect on incidence of Caesarean birth, although the Dublin trial results, with regard to incidence of Caesarean section, emphasize the importance of considering intrapartum fetal monitoring as just one part of the overall supervision of labour. Finally, it must be emphasized that the method of fetal monitoring chosen may be strongly influenced by factors other than scientific evidence, as in the United States where the medicolegal climate is such that failure to rigorously document absence of fetal distress/true birth asphyxia may result in a harrowing lawsuit. It is a position this author has developed considerable sympathy with in recent years.
Boylan
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D000653:Amniotic Fluid / Q000032:analysis; D001238:Asphyxia Neonatorum / Q000175:diagnosis*; D001925:Brain Damage, Chronic / Q000175:diagnosis*; D004562:Electrocardiography / Q000379:methods; D005260:Female; D005317:Fetal Growth Retardation / Q000175:diagnosis; D005311:Fetal Hypoxia / Q000175:diagnosis*; D005323:Fetal Monitoring / Q000379:methods*; D006340:Heart Rate, Fetal; D006801:Humans; D007231:Infant, Newborn; D007744:Obstetric Labor Complications / Q000175:diagnosis; D011247:Pregnancy; D012307:Risk Factors