Arbitraje Descripción

We have shown that there is large variation in classification of the intrapartum CTG, even when FIGO guidelines are used. Inter-observer agreement for the normal CTG was good but Case

Timing of decision to intervene according to observers A1-C2

A1 A2 B1 B2 C1 C2 10 S - 4 S - 4 S - 4 S - 4 S - 4 S - 4 19 N N S - 4 N N N 20 C - 3 S - 4 S - 4 N C ± 3 N 25 S - 1 S - 3 S - 3 N N N 34 S - 4 S - 4 S - 4 S - 4 N S ± 4 41 C - 2 S - 4 S - 4 N S ± 4 S ± 4 51 N N C - 3 N S ± 4 C ± 4 57 N N N N N N 68 C - 1 C - 2 C - 1 C - 1 C ± 2 C ± 1 69 C - 2 S - 4 C - 3 C - 2 C ± 3 C ± 3 70 S - 3 C - 4 C - 3 S - 3 S ± 4 S ± 3 A1 A2 B1 B2 C1 C2 CTG classification 0.64 0.59 0.67 0.52 0.62 0.54 Decision to intervene 0.72 0.68 0.75 0.61 0.62 0.64

decreased when the CTG became intermediary or abnormal. (Pre)terminal traces again showed a moderate to good inter-observer agreement. The slightly higher percentages of inter-observer agreement at T1 (compared with T0) may be explained by a small learning effect of reading and classifying CTG traces.

For the normal CTG, observers with little (category C) and much (category A) STAN®

experience agreed better than observers with half a year of experience (category B). This PLJKWEHGXHWRWKHIDFWWKDWWUDLQLQJRIµEHJLQQHUV¶LVVWLOO fresh and they therefore follow the guidelines more strictly than other observers. Experts may agree better because of

their larger experience. For all CTG classes, agreement EHWZHHQµH[SHUWV¶DQGREVHUYHUVZLWK at least half a year of experience with ST-analysis (A1-B1) appeared to be best.

The observers agreed better on the decision to intervene than on the CTG classification, especially on the decision to perform no intervention. Observers with less than half a year of experience with ST-analysis µEHJLQQHUV¶DJUHHGEHVW+RZHYHU their agreement with more experienced observers was poor to moderate. This may indicate that alWKRXJK µEHJLQQHUV¶ agree well with each other, their judgement concerning decision to intervene seems to be different and perhaps wrong compared with more experienced observers, assuming the latter WRPDNHPRUHRIWHQWKHFRUUHFWGHFLVLRQµUHIHUHQFH¶

In RXUVWXG\ZHIRXQGH[FHOOHQWDJUHHPHQWIRUµEHJLQQHU¶ observers at T0, whereas at T1 for this group agreement was considered moderate. Perhaps, their excellent agreement at

T0 was accidentally achieved, also due to relatively small numbers.

In the STAN® _{methodology, the decision to intervene or otherwise depends on both CTG}

interpretation and interpretation of ST events. Our study indicates that the efficacy

of this method of fetal surveillance, although proven to be promising,9,12 _{seems hampered by a}

poor to moderate agreement for CTG interpretation. It was reassuring that agreement on normal and (pre)terminal CTG traces was relatively good since with such heart rate patterns additional information on ECG waveforms is not required. Although agreement for CTG interpretation was moderate, the observers agreed quite well on the timing of an intervention, which in the end is the most important decision in daily clinical practice. Possibly, the

availability of ST information and use of STAN® _{guidelines result in a more standardised}

assessment of the CTG and the total clinical situation, which may eventually result in better agreement on decision to intervene.

There are some possible limitations of this study that have to be discussed. The first may seem the relatively low number of abnormal and (pre)terminal CTG traces in the selected women. We, however, explicitly decided not to overrepresent such traces to ensure that observers were not exposed to abnormal CTGs only and that they paid full attention to the whole spectrum of CTG tracings. For fetal surveillance, agreement on both normal and abnormal CTG assessments is important: disagreement on abnormal CTGs may result in infants being damaged by hypoxia and disagreement on normal CTGs may cause unnecessary interventions. It is therefore necessary to consider agreement for abnormal and normal CTG assessments separately.

Inter- and intra-observer agreement | 35

Second, since this study concerns classification of CTG traces, it is possible that some observer bias has played a role because a 30-minute CTG trace may both show intermediary and abnormal parts. Although in advance, observers were asked to classify such traces in the worst category, this still may have increased inter-observer variability.

7KLUG IRU VLPSOLFLW\ ZH FKRRVH WR SUHVHQW GDWD RQ µEHWZeen FDWHJRU\¶ DJUHHPHQW IRU &7* classification and decision to intervene only for the first observer combinations A1-B1, A1- C1 and B1-C1. Agreement for observer pairs A2-B2, A2-C2 and B2-C2 was similar.

Finally, a drawback of this study may be the use of paper printouts for CTG assessment, which may create a situation without optimal mimicry of clinical practice.

In conclusion, we found a large variation in classification of the intrapartum CTG, despite the use of FIGO guidelines and availability of ST information. Agreement for the normal and (pre)terminal CTG trace was good but decreased when CTG traces were intermediary or abnormal. Agreement was better on the decision to intervene, especially on the decision not to intervene and on the timing of the intervention. This suggests that addition of information regarding fetal ECG, especially in case of intermediary or abnormal CTG traces, results in a more standardised decision to intervene or otherwise.