Comments on past and present situation of intensive monitoring of the fetus during labor.
Modern intensive monitoring of the fetus during labor affords the opportunity for the greatest possible safety to the infant, whilst at the same time dispensing with unnecessary operations to terminate labor which can be dangerous for the mother and her child. Developments over the past 28 years, since cardiotocography has been in clinical use, have unfortunately also been accompanied by confusion and mistakes. We think that there are two main reasons for this: I. Many who use cardiotocography have not assessed its efficiency correctly. Heart rate pattern with all their variations have too often been regarded as the only diagnostic criteria for the determination of fetal hypoxia. However this procedure only allows a rough selection of actually endangered fetuses. In more than 50% of the cases with a suspicious or pathologic cardiotocogram there is no concrete clinical evidence of manifest danger of hypoxia. II. Investigations concerning the practical importance of monitoring the fetus during labor were often not based on actual clinical indications. Attempts were made to prove that continuous electronic monitoring of the fetal heart rate could be replaced by simple traditional auscultation. Furthermore due to failure to appreciate the real efficiency of cardiotocography, this truly excellent method was in fact blamed for the faults arising from wrong interpretation, instead of underlining the lack of logic of the investigators concerned. After all, several prospective studies, that have examined the efficiency of various monitoring strategies, demonstrate the shortcomings of these techniques in the clinical setting and have shown them to have no relevance in every practice. Presently the most suitable way to monitor the fetus during labor is to combine cardiotocography with a biochemical method. At the moment fetal blood analysis is the most suitable test to be performed in cases where the cardiotocogram is not normal. Then the role of fetal blood analysis is to find out whether in fact a danger of hypoxia is threatened or not. Today the most urgent task when monitoring the fetus during labor is not so much to reduce the number of cases of cerebral palsy since these are seldom caused by intrapartum asphyxia. The major objective is now recognised to be to prevent early morbidity of the fetus, newborn, and the consequences that flow from this. The excellent results of combined intensive monitoring of the fetus during labor are particularly well illustrated by the intrapartum mortality in our hospital during different periods when monitoring practice has been progressively and methodically improved by stages. During the period when monitoring consisted of simple auscultation used on its own, the intrapartum mortality was 0.56%. After the introduction of fetal blood analysis--at that time cardiotocography did not yet exist--the mortality sank to 0.32%. During the first ten years of cardiotocography combined with fetal blood analysis the mortality reduced further to 0.17%, and during the following 13 years it reached to a minimal level of 0.4%. Finally, in this review, other aspects are commented on such as oximetry. Oximetry, presently used as pulse oximetry, as an additional biochemical method will possibly be incorporated as the third method of monitoring the fetus during labor. Oximetry could also be used as an automatic alarm system in the labor ward when fetal O2 levels drop below a particular limit to draw the attention of the staff to the case concerned. Up to now this has not been convincingly achieved with the use of cardiotocography.