Fetal heart rate classification in routine use: Do your prefer a 3-tier or a 5-tier classification?

OBJECTIVE: To assess the current use of a five-tier fetal heart rate (FHR) classification system (National College of French Obstetricians and Gynecologists, CNGOF, 2007) and of a three-tier system (Federation International of Gynecology and Obstetrics, FIGO, 2015). MATERIALS AND METHODS: This was a single-center prospective study conducted in April 2016. Midwives were asked to classify FHR hourly during their patients' labors according to two classification systems (CNGOF and FIGO). For each system the midwives rated from 0 to 10 the following elements after delivery: ease of FHR classification, the memorization of the classification, access to routine use, and help with the decision of a second-line examination. Finally, they had to choose which classification system seemed most helpful in their clinical practice. RESULTS: Forty-six patients were included in the study. The median score for the ease of FHR classification according to the CNGOF system was 7, versus 8 according to the FIGO system (p<0.05). The median score for the ease of remembering the classification was 4 for CNGOF versus 8 for FIGO (p<0.05). The FIGO classification system was considered the easiest to use in 76% of cases and the CNGOF system was the most helpful in 61% of cases. The CNGOF system was seen as a help in deciding on a second-line examination in 70% of cases and the FIGO was a help in 63% of cases. CONCLUSION: The three-tier FIGO classification system seemed easier to use but the five-tier CNGOF classification system was more helpful. The choice of which system to use should be discussed within each medical team.

Combined maternal-associated risk factors with intrapartum fetal heart rate classification systems to predict peripartum asphyxia neonates.

OBJECTIVE: To improve the predictive ability for identification of peripartum asphyxia neonates by using the 3-tier and 5-tier fetal heart rate (FHR) classification systems. STUDY DESIGN: A retrospective case-control study comparing peripartum asphyxia neonates and no asphyxia neonates was conducted. The FHR tracings were classified into the 3-tier and 5-tier systems by the two reviewers. Pearson's X2 or Fisher's exact tests was used for comparisons between the groups. Logistic regression models were used to identify factors associated with peripartum asphyxia neonates. Odds Ratios (OR) and Likelihood Ratios (LR) with 95% confidence intervals (CI) were calculated from the regression coefficients. RESULTS: A total of 36 peripartum asphyxia fetuses (5.0%) were enrolled. Overall, the performance of category II and suspicious tracings to detect peripartum asphyxia neonates was higher than the yellow and orange tracings with 61% and 67% sensitivity, respectively. The 5-tier FHR classification had higher specificity than the 3-tier system (82-99%). The predictive ability to detect peripartum asphyxia neonates by the 5-tier FHR classification was highest when combined with maternal-associated risk factors (AUC 0.67-0.72). CONCLUSION: Maternal-associated risk factors combined with an abnormal 5-tier FHR classification had high predictive ability and specificity to detect peripartum asphyxia neonates.

Submitting medico-legal intra-partum CTG (I-P CTG) monitoring to the Bolam and Bolitho principles.

The article analyses some of the seeming weaknesses of the Bolam and Bolitho tests as applied to electronic foetal monitoring in labour, in the form of intra-partum CTG monitoring. Homing on to such aspects as confirmation of foetal hypoxia/acidosis, it evaluates the Bolam and Bolitho tests in the context of evidence-based medicine versus traditionally held views, which still hold their own in medical jurisprudence. Case law examples are quoted to illustrate various points. The discussion is of practical relevance both to the individual obstetrician as well as to national budgetary implications, bearing in mind, that, for example, in 2011, 'birth asphyxia' comprised 50% of the UK NHS litigation costs, and in the 2000-2010 decade, the same NHS forked out £3.1 billion for maternity medico-legal claims (the highest of any speciality), mostly involving cerebral palsy and CTG misinterpretation. The article concludes with suggestions to help level the potential extant equivocity between legal principle and medical practice. It also looks at the ruling in Montgomery v Lanarkshire Health Board, UK Supreme Court, and its challenge to Bolam. The implications pose a serious and overdue challenge to a test, born in 1957 and lacking the necessary qualities to serve many 21st century medical quandaries, including the ones raised here.

Inter-observer reliability of 4 fetal heart rate classifications.

OBJECTIVE: Different classification of fetal heart rate (FHR) pattern have been proposed: FHR classified as either "reassuring" or "non-reassuring", the National Institute of Child Health and Human Development (NICHD) published in 2008 a 3-tier system, the French College of Gynecology and Obstetrics (CNGOF) recommended in 2013 a 5-tier system and recently in 2015, the Federation International of Gynecology and Obstetrics (FIGO) proposed a new classification based on a 3-tier system. Our objective was to assess the inter-observer reliability of these 4 existing classifications. STUDY DESIGN: Four observers reviewed 100 FHR without clinical information. FHR were obtained from term singleton pregnancies. Fetal heart rate patterns were classified by one 2-tier ("reassuring vs. non-reassuring"), two 3-tier (NICHD 2008 and FIGO 2015), and one 5-tier (CNGOF 2013) fetal heart classifications. RESULTS: The global agreement between observers was moderate for each classification: 0.58 (0.40-0.74) for the 2-tier, 0.48 (0.37-0.58) for the NICHD 2008, 0.58 (0.53-0.63) for the CNGOF 2013 and 0.59 (0.49-0.67) for the FIGO 2015 classification. When FHR was classified as reassuring, it was classified as normal in 85.5% for the NICHD 2008 and in 94.5% for the FIGO 2015. For the CNGOF 2013, 65.0% were classified as normal and 32.5% as quasi normal. There was strong concordance between FIGO category I and "reassuring" FHR (kappa=0.95). CONCLUSION: Inter-observer agreement of FHR interpretation is moderate whatever the classification used. To evaluate the superior interest of one classification, it will be interesting to compare their impact on need of second line techniques and on neonatal outcome.

A cross-sectional comparison of three guidelines for intrapartum cardiotocography.

OBJECTIVE: To compare the cardiotocography classification systems outlined by the International Federation of Gynecology and Obstetrics (FIGO) in 2015 and the UK National Institute for Health and Care Excellence (NICE) in 2007 and 2014. METHODS: A cross-sectional observational study of cardiotocography practices at a UK hospital was conducted among labor ward staff (n=21) from November 1 to November 31, 2015. All observers classified ten cardiotocography traces according to the three guidelines using a bespoke form. Outcome measures included interobserver agreement (κ values), percentage agreement, intervention rate, and perceived ease of use. RESULTS: The κ values were 0.38 (FIGO 2015), 0.37 (NICE 2007), and 0.34 (NICE 2014). The percentage agreement was identical across the three systems for both normal cardiotocography results (100.0%) and for intermediate or suspicious results (80.9%). By contrast, the percentage agreement for abnormal or pathological findings was 47.6% for NICE 2014, 76.2% for FIGO 2015, and 91.0% for NICE 2007 guidelines. Among 210 observations, intervention was deemed necessary for 48 (22.9%) for FIGO 2015, 29 (13.8%) for NICE 2014, and 56 (26.7%) for NICE 2007 guidelines. The FIGO 2015 system was considered the easiest to use by 13 (61.9%) observers. CONCLUSION: Interobserver agreement of cardiotocography classification is suboptimal. The FIGO 2015 system offered favorable agreement scores, perceived ease of use, and a moderate intervention rate.

Diagnostic Accuracy of the FIGO and the 5-Tier Fetal Heart Rate Classification Systems in the Detection of Neonatal Acidemia.

Objective The objective of this study was to determine ability to detect neonatal acidemia and interobserver agreement with the FIGO 3-tier and 5-tier fetal heart rate (FHR) classification systems. Design This was a case-control study. Setting This study was set at the University Medical Center. Population A total of 202 FHR tracings of 102 women who delivered an acidemic fetus (umbilical arterial cord gas pH ≤ 7.10 and BE < - 8) and 100 who delivered a nonacidemic fetus (umbilical arterial cord gas pH > 7.10) were assessed. A subanalysis was performed for those fetuses who suffered severe metabolic acidemia (pH ≤ 7.0 and BE < - 12). Methods Two reviewers blind to clinical and outcome data classified tracings according to the new 3-tier system proposed by the FIGO and the 5-tier system proposed by Parer and Ikeda. Main Outcome Measures Sensitivity and specificity for detecting neonatal acidemia and interobserver agreement in classifying FHR tracings into categories of both systems were studied. Results The 3-tier system showed a greater sensitivity and lower specificity to detect neonatal acidemia (43.6% sensitivity, 82.5% specificity) and severe metabolic acidemia (71.4% sensitivity, 74.0% specificity) compared with the 5-tier system (36.3% sensitivity, 88% specificity and 61.9% sensitivity, 80.1% specificity, respectively). Both systems were compared by area under the receiver-operating characteristic curve, with comparable predictive ability for detecting neonatal acidemia (FIGO-area under the curve [AUC]: 0.63 [95% confidence interval [CI]: 0.57-0.68] and Parer-AUC: 0.62 [95% CI: 0.56-0.67]). Interobserver agreement was moderate for both systems, but performance at each specific category showed a better agreement for the 5-tier system identifying a pathological tracing (orange or red, κ: 0.625 vs. pathological category, κ: 0.538). Conclusion Both systems presented a comparable ability to predict neonatal acidemia, although the 5-tier system showed a better interobserver agreement identifying pathological tracings.

Cardiotocographic findings in the second stage of labor among fetuses delivered with acidemia: a comparison of two classification systems.

BACKGROUND: The RCOG classification system of CTG trace is widely used for the analysis of the fetal heart rate during the first and second stage of labor. Other authors proposed specific classification systems for the second stage traces. OBJECTIVE: To evaluate the accuracy of RCOG and Piquard cardiotocographic patterns classification systems in predicting fetal acidemia in the second stage of labor. STUDY DESIGN: This was a nested retrospective case-control study including fetuses delivered with metabolic acidemia in the second stage of labor and a matched group of non-acidemic fetuses as controls. Cases and controls were selected from the electronic medical records of the University Hospital of Bologna between 2008 and 2013. The last 60min of the cardiotocograms recorded during the second stage of labor were independently classified by a senior consultant and a trainee according to RCOG and Piquard classifications. The inter-observer agreement and the accuracy of the two classifications in predicting fetal acidemia were evaluated. RESULTS: In all, 82 acidemic fetuses and 164 controls were recruited in the study period. Regarding the CTG traces assessment, the inter-observer agreement was moderate for both the categorizations (RCOG κ=0.584). Unclassifiable CTG patterns were more frequent among acidemic fetuses vs controls either at RCOG and at Piquard evaluation (26.8% vs 7.9%, p<0.001). Both systems yielded a moderate and comparable ability to predict fetal acidemia (RCOG ROC AUC=0.731; 95% CI 0.660-0.795; Piquard ROC AUC=0.773; 95% CI 0.704-0.833. DeLong z-test=1.186, p=0.236). CONCLUSIONS: RCOG and Piquard systems have a moderate accuracy in identifying acidemic fetuses during the second stage of labor. The occurrence of unclassifiable findings seems significantly more common among the acidemic fetuses.

Variable decelerations: do size and shape matter?

OBJECTIVE: To determine the ability of variable decelerations and 8 subtypes, defined by size and shape, to discriminate tracings between babies with normal umbilical artery gases (N) and those with metabolic acidemia (MA). METHODS: Tracings from the last 4 hours from N-3320 babies with base deficit levels under 8 mmol/L, and from MA-316 babies with base deficits over 12 mmol/L were analyzed using computerized pattern recognition. We created receiver operating characteristic curves and area under the curves (AUCs) for each deceleration subtype. RESULTS: Only 3 subtypes showed significant discrimination: those with a prolonged duration (AUC 0.6109 P < 0.0001), loss of internal variability (AUC 0.5694 P < 0.0001) or with "sixties" criteria (AUC 0.5997 P < 0.0001). A variable deceleration met the sixties criteria if two or more of the following were present: depth was 60 bpm or more, lowest value was 60 or less, duration was 60 seconds or longer. All other subtypes were no better than chance. CONCLUSIONS: Finer gradation within the middle category of electronic fetal monitoring classification is needed because most tracings, including those from babies with MA, will be located in the Category II. This analysis identifies which variable decelerations have a significant association with MA and which do not.

Intra- and interobserver variability of intrapartum cardiotocography: a multicenter study comparing the FIGO classification with computer analysis software.

OBJECTIVE: To evaluate and compare the computer analyzing software system with subjective interpretation using the FIGO classification of intrapartum cardiotocograms. METHODS: Twenty-four obstetricians and 19 midwives from 3 hospitals [19 junior (≤3 years) and 24 senior (>3 years) experience] participated in this study. Forty-three doctors and midwives interpreted intrapartum cardiotocographic (CTG) readings from 12 parturients without knowing the clinical outcome. Two CTG readings were repeated for evaluation of the intraobserver variability. Inter- and intraobserver agreement in CTG interpretation using the FIGO score and the computer analyzing software was assessed via proportions of agreement (Pa), with 95% confidence intervals. The level of inter- and intraobserver agreement was analyzed by calculating Pa values for CTG baseline, variability, accelerations and decelerations. RESULTS: In total, for all parameters of the FIGO classification, Pa was very low. The highest 95% confidence level of Pa was found for the baseline parameter (0.49-1.01), and the lowest for the parameter acceleration. No significant difference was seen between obstetricians and midwives as well as between junior and senior experience. In assessments of normal cases, the Pa were significantly higher than in pathological readings. CONCLUSION: Computer analyzing software can reduce the high inter- and intraobserver variability; however, further studies are needed to find out whether this can improve fetal outcome and reduce the number of Cesarean sections.

Electronic fetal heart rate monitoring: where are we now?

Electronic fetal heart rate monitoring (EFM) continues to be the primary method utilized for fetal assessment in the United States. Standardization of nomenclature associated with this perinatal technology has evolved over the past 40 years such that the current nomenclature recommended by the National Institute of Child Health and Human Development (NICHD) has been adopted by professional perinatal organizations as the agreed-upon method for professional communication and documentation. Current research continues to focus on the optimal management of intrapartum fetal heart rate tracings. The clinical controversies and challenges related to electronic fetal heart rate monitoring continue to evolve.

Graded classification of fetal heart rate tracings: association with neonatal metabolic acidosis and neurologic morbidity.

OBJECTIVE: The objective of the study was to measure the performance of a 5-tier, color-coded graded classification of electronic fetal monitoring (EFM). STUDY DESIGN: We used specialized software to analyze and categorize 7416 hours of EFM from term pregnancies. We measured how often and for how long each of the color-coded levels appeared in 3 groups of babies: (A) 60 babies with neonatal encephalopathy (NE) and umbilical artery base deficit (BD) levels were greater than 12 mmol/L; (I) 280 babies without NE but with BD greater than 12 mmol/L; and (N) 2132 babies with normal gases. RESULTS: The frequency and duration of EFM abnormalities considered more severe in the classification method were highest in group A and lowest in group N. Detecting an equivalent percentage of cases with adverse outcomes required only minutes spent with marked EFM abnormalities compared with much longer periods with lesser abnormalities. CONCLUSION: Both degree and duration of tracing abnormality are related to outcome. We present empirical data quantifying that relationship in a systematic fashion.

Prevention of birth asphyxia: responding appropriately to cardiotocograph (CTG) traces.

Birth asphyxia is a broad term that refers to intrapartum asphyxia sufficient to cause neurological damage in some newborns and, rarely, intrapartum or neonatal death. Cerebral palsy and long-term neurological complications such as learning difficulties and motor impairments may be due to causes other than birth asphyxia. Several intrapartum events may cause asphyxia (i.e. hypoxia and metabolic acidosis) leading to the likelihood of neurological injury. The cardiotocograph (CTG) is a screening tool that is used to assess fetal well-being during labour and to identify the possibility of asphyxia. Abnormality of the CTG, sometimes severe enough to be described as a pathological trace, is commonly termed 'fetal distress', although many fetuses with such traces may not have hypoxia and metabolic acidosis. In current practice, the events are appropriately termed 'pathological CTG trace' or 'acidotic pH' rather than 'fetal distress'. Accurate interpretation of CTG is essential, and it is important to recognize a fetus that shows a pathological CTG in labour that may imply possible hypoxia and birth asphyxia. Considering the wider clinical picture in interpreting the CTG, and taking timely and appropriate action based on the findings, may help prevent birth asphyxia.

Inconsistencies in classification by experts of cardiotocograms and subsequent clinical decision.

Inter-observer agreement in the interpretation according to the FIGO guidelines of 33 cardiotocographic tracings by experts and subsequent clinical decision was evaluated, using the kappa statistic (K) and the proportions of agreement (Pa). Overall agreement in the classification of tracings was fair (K = 0.48) and was better for normal (Pa = 0.62), than for suspicious (Pa = 0.42) or pathologic tracings (Pa = 0.25). Overall agreement on clinical decision was slightly higher (K = 0.59), but mostly was centred on the decision to take 'no action' (Pa = 0.79). Experts especially disagreed over the decisions to 'monitor closely' (Pa = 0.14) or to 'intervene immediately' (Pa = 0.38). These limitations should be taken into account in clinical audits and in medical jurisprudence.

Interpretation of low kappa values.

The use of the kappa statistic is commonly accepted as a measure for interobserver variability. However, in some situations, the interpretation of kappa should be handled with care. In this study 21 obstetricians were asked to segment and classify 13 cardiotocographic recordings for the major fetal heart rate (FHR) patterns acceleration, baseline FHR level, deceleration and undefined segments. In two cases the kappa statistic showed a poor group agreement. These low kappa values, however, were mainly due to the high proportion of baseline segments indicated by the referees. This finding will be exemplified by a discussion of one of the cases.

Clinical overview of cardiotocography.

Twenty years after its widespread introduction, the role of continuous fetal heart rate and contraction monitoring in labour (cardiotocography, CTG) remains uncertain. Although a normal pattern is very reassuring about fetal condition, the predictive value of an abnormal pattern is low. In most studies the use of CTG has been associated with an increase in intervention in labour, particularly caesarean section, without clear evidence of benefit. Fetal blood sampling is the most useful associated technique for minimizing unnecessary intervention. The relationship between fetal heart rate, fetal blood pH changes and long-term outcome remains obscure and further work to clarify this relationship is urgently needed.