Objective: To evaluate the relationships between scalp-pH and CTG plus ST waveform analysis of the fetal ECG (STAN) clinical guidelines as indicators of intrapartum hypoxia in term fetuses born with cord artery acidemia.
Study design: Data from 6999 term deliveries monitored by the STAN® S 21 as part of an EU multi-center study on clinical implementation of the STAN methodology for intrapartum fetal surveillance were analyzed. We identified 911 cases where a scalp-pH was obtained, including 53 cases with cord artery acidemia (pH < 7.06). Lag times between ST events and scalp-pH and time to delivery were related to cord artery metabolic and respiratory acidosis and neonatal outcome.
Results: 43 fetuses were identified by CTG plus ST as being in need of intervention 31 (25–46) minutes before delivery (median, 95% Cl). In five, no indications were given and in another five there were inadequate data. Fifteen cases with metabolic acidosis required special neonatal care, all 14 cases adequately monitored on STAN had indications to intervene for 19 minutes or more. In 30 adequately recorded cases, fetal blood sampling (FBS) was obtained within the last hour of labor. In 22 cases, FBS was obtained 13 (7–24) minutes after STAN guidelines had indicated abnormality and in eight no ST changes had occurred at time of FBS. The corresponding FBS data were pH 7.10 (7.01–7.15) and pH 7.21 (7.08–7.31), respectively, P = 0.01. In cases of metabolic acidosis, scalp-pH fell 0.01 units per minute after a baseline T/QRS rise was recorded during the second stage of labor. Apart from one newborn that died at 2 h from E. Coli septicemia, none of the neonates were affected neurologically.
Conclusion: Cardiotocography plus ST analysis provides accurate information about intrapartum hypoxia similar to that obtained by scalp-pH.
1 Amer-Wahlin I, C Hellsten, H Norén, H Hagberg, A Herbst, I Kjellmer I et al.: Intrapartum fetal monitoring: Cardiotocography versus cardiotocography plus ST analysis of the fetal ECG. A Swedish randomized controlled trial. Lancet358 (2001) 534Search in Google Scholar
2 Amer-Wahlin I, P Bördahl, T Eikeland, C Hellsten, H Norén, T Sörnes, KG Rosén: ST analysis of the fetal electrocardiogram during labor: Nordic observational multicenter study. J Mat Fet Neonat Med12 (2002) 260Search in Google Scholar
3 Arulkumaran S, H Lilja, K Lindecrantz et al.: Fetal ECG waveform analysis should improve fetal surveillance in labor. J Perinat Med18 (1990) 13Search in Google Scholar
4 Clark SL, RH Paul: Intrapartum fetal surveillance: the role of fetal scalp blood sampling. Am J Obstet Gynecol153 (1985) 717Search in Google Scholar
5 Hökegård KH, BO Eriksson, I Kjellmer, R Magno, KG Rosén: Myocardial metabolism in relation to electrocardiographic changes and cardiac function during graded hypoxia in the fetal lamb. Acta Physiol Scand113 (1981) 1Search in Google Scholar
6 Impey L, M Reynolds, K MacQuillan, S Gates, J Murphy, O Sheil: Admission cardiotocography: a randomised controlled trial. Lancet361 (2003) 465Search in Google Scholar
7 Luzietti R, R Erkkola, U Hasbargen, LA Mattsson, JM Thoulon, KG Rosén: European Community multi Center Trial “Fetal ECG Analysis During Labor”: ST plus CTG analysis. J Perinat Med27 (1999) 431Search in Google Scholar
8 Norén H, I Amer-Wahlin, H Hagberg, A Herbst, I Kjellmer, K Marsal, P Olofsson, KG Rosén: Fetal electrocardiography in labor and neonatal outcome: Data from the Swedish randomized controlled trial on intrapartum fetal monitoring. Am J Obstet Gynecol188 (2003) 183Search in Google Scholar
9 Parer JT, T King: Fetal heart rate monitoring: is it salvageable? Am J Obstet Gynecol182 (2000) 982Search in Google Scholar
10 Rosén KG, A Dagbjartsson, BA Henriksson, H Lagercrantz, I Kjellmer: The relationship between circulating catecholamines and ST waveform in the fetal lamb electrocardiogram during hypoxia. Am J Obstet Gynaecol149 (1984) 190Search in Google Scholar
11 Saling E: Fetal scalp blood analysis. J Perinat Med9 (1981) 165Search in Google Scholar
12 Siggaard-Andersen O: An acid base chart for arterial blood with normal and pathophysiological reference areas. Scand J Clin Lab Invest27 (1971) 239Search in Google Scholar
13 Thacker SB, D Stroup, M Chang: Continuous electronic heart rate monitoring for fetal assessment during labor. Cochrane Database Syst Rev CD000063 (2001)Search in Google Scholar
14 Westgate J, KR Greene: How well is fetal blood sampling used in clinical practice? Br J Obstet Gynaecol101 (1994) 250Search in Google Scholar
© Walter de Gruyter