45 years of fetal heart rate monitoring in BJOG CHRISTOPHER REDMAN, NUFFIELD DEPARTMENT OF OBSTETRICS AND GYNAECOLOGY AND JOHN RADCLIFFE HOSPITAL, OXFORD, UK
.................................................................................................................................................................. years ago the fetus was Fifty inaccessible to objective measurement. Thereafter, the development of electronic fetal heart rate (FHR) monitoring and ultrasound imaging of the fetus revolutionised care. FHR patterns, fetal size, shape, regional circulation, and movements could be routinely assessed by increasingly sophisticated techniques, yielding crucial insights into fetal health and the need to intervene or not. Continuous FHR monitoring was quickly implemented for intrapartum care. Purists argue about its effectiveness. Practical clinicians noted the virtual disappearance of fetal death in labour associated with its introduction (Erkkola et al. Acta Obstet Gynecol Scand 1984;63:459–62), and its usefulness to detect fetal distress before labour was also appreciated (Huntingford & Pendleton J Obstet Gynaecol Br Commonw 1969;76:586–95). Practice diverged on opposite sides of the Atlantic. American clinicians preferred to challenge the fetus by oxytocin-induced contractions (stress test). Following the lead of Spurrett et al. in this journal (J Obstet Gynaecol Br Commonw 1971;78:894– 900), UK clinicians found that the non-stress test (NST) was simpler and nearly as informative. The FHR measurement proved to be unexpectedly complex, which remains an unresolved problem that continues to frus-
trate clinicians seeking diagnostic certainty. Furthermore, whatever the diagnostic method, the full extent of fetal dysfunction can be obscured by powerful mechanisms that maintain apparently normal function under intensifying stress. Hence, when decompensation occurs, it can occur very suddenly. The diagnosis of a terminal state is easy, but its prediction is more difficult. The unresolved problem is calibrating the grey zone between normality and the terminal trace. Computerised analysis, first described in these pages more than 30 years ago (Visser et al. BJOG 1981;88:792–802), has helped by standardising the interpretation and measurement of grey-zone features and raises expectations of a more evidence-based approach in the future. The lack of specificity, intrinsic to tests of incipient fetal distress, can be addressed by second-tier tests, of which fetal scalp blood sampling is the paradigm. But its usefulness and safety is now under scrutiny (Chandraharan BJOG 2014;121:1056–62). Alternative approaches include fetal pulse oximetry (now abandoned) or analysis of fetal electrocardiographic (ECG) waveforms. The latter is now widely available as the STAN system (Becker et al. BJOG 2011;118:1239–46), and adds new information, enabling fewer operative deliveries and fetal blood samplings.
In this issue, Kessler et al. systematically analyse for the first time the FHR characteristics of breech fetuses monitored by the STAN technique. They find that there is significantly greater signal loss and fewer ST segment changes, but that there are more compromised fetuses with pre-terminal CTG changes. They comment that it is not surprising that it is more difficult to gain an ECG from the breech than from the scalp, and that breech babies are exposed to less direct face stimulation and head compression, which may alter their state of arousal and associated ECG changes, mediated by sympathetic mechanisms. They conclude, nevertheless, that STAN monitoring is valid for breech presentations. Over nearly 50 years this journal continues to document the fascinating evolution of FHR monitoring, which is enabling better care; however, progress is much slower than was anticipated. Disclosure of interests Professor Redman was a coinventor of the Dawes Redman computerised system for FHR analysis, now marketed by Huntleigh Healthcare, Cardiff, UK. He receives no personal financial benefits from Huntleigh Healthcare, who provide continuing financial support for the research and development of the Dawes Redman system. &
© 2015 Royal College of Obstetricians and Gynaecologists