A C TA Obstetricia et Gynecologica
AOGS LE TT E R TO THE EDIT O R
Admission CTG test: “to be or not to be”
Sir Admission cardiotocography (CTG) tests have been used routinely since the early 1990s. The objective of the test is to identify a pathological CTG early after admission to the delivery unit. As it usually is taken during contractions, it functions as a stress test, allowing us to assess the fetal answer to the hypoxic stress related to contractions. In the publication “The admission CTG: is there any evidence for still using the test?”(1), Ellen Blix argues against the use of admission test because: (i) it does not predict delivery outcome, (ii) it has not been shown that admission tests lower poor outcome, and (iii) the high frequency of
(a)
abnormal CTG tracings (20–30%) causes an increased risk of operative delivery. Regarding points (i) and (ii), Skall vara referens till pa˚sta˚ende (i) och (ii) in her argument she starts by saying that “the admission test was introduced as a screening test for fetal distress in early labor,” after which she states that “the admission test was introduced as a screening test for fetal distress at labor.” Thereafter, there is a discussion of fundamentals in statistics and she summarizes the relation of the admission test and fetal and maternal outcome at delivery. None of the outcomes discussed by Ellen Blix actually assesses the admission test. The admission
(b)
(c)
Figure 1. Three different pathological admission CTG curves: all low-risk pregnancies, but delivered by immediate cesarean section after admission CTG. (a) Umbilical cord pH 6.88, uneventful follow-up. (b) Umbilical cord pH 6.85, 15% in weight deviation, uneventful follow-up. (c) Umbilical cord pH 7.26, 18% in weight deviation, Apgar 5, develops postnatal seizures and a severe hypoxic encephalopathy; the newborn died in the first postnatal week.
428
ª 2013 Nordic Federation of Societies of Obstetrics and Gynecology, Acta Obstetricia et Gynecologica Scandinavica 93 (2014) 428–432
Letter to the Editor
test is, and will always be, a final assessment of fetal health on admission to the delivery unit, and not a predictive test for later outcome. The goal is to lower the risk of severe asphyxia, neurological sequelae and intrauterine death among the very few fetuses already compromised on admission to the delivery unit. This is not investigated in her commentary. I refer to pathological CTG tracings taken on admission showing changes that might be difficult to auscultate (Figure 1). With reference to point (iii) the high number of abnormal CTG tracings is a major problem. In the original studies of the admission test there were only 1% pathological tracings and another 4% of non-reactive tracings (2). Later in Lund (nonpublished) the prevalence of pathological or non-reactive tracings was down to 2.9% (3). It is integral to the method that a fetus showing a non-reactive tracing should be stimulated to show potential for reactivity. If reactivity is shown, the tracing is normal. Ellen Blix has a point – and we have a problem – if there is a drift in CTG interpretations with an increasing rate of false abnormal CTGs causing unnecessary operative delivery. However, this problem should be solved by improving CTG interpretation and not by omitting the admission test. A bonus of the admission test is that it helps us to identify cases with preexisting neurological impairment or intrauterine fetal death (IUFD) immediately on admission to the delivery unit. A diagnosis of IUFD is tragic but the admission test makes it possible for the initiation of an adequate grieving process. If the diagnosis is made hours later, this will often initiate thoughts of negligence on the part of the delivery unit and at times unnecessary legal action. In addition, cases of IUFD during delivery are extremely rare today. Further, the admission CTG may give an indication of preexisting neurological impairment, which often would be impossible to detect with auscultation (Figure 1c). These rare cases are most often unidentified fetal growth restriction with low reserve capacity for tolerating contractions during delivery. It has been shown that awareness of growth restriction improves outcome substantially (4).
In my experience the admission test is an excellent way of identifying the few yearly cases with pathological CTG and IUFD on arrival at the delivery unit, which helps us to initiate the most adequate management and facilitate the grief process. It is, however, a major problem if there is a high prevalence of falsely abnormal interpretations of CTG, but this should solved by education and critical revision of CTG interpretations rather than by omitting the admission test.
Pelle G Lindqvist* Clintec, Obsterics and Gynecology, K57, Karolinska University Hospital, Stockholm, Sweden *Corresponding Author: Pelle G Lindqvist E-mail: [email protected] DOI: 10.1111/aogs.12297
References 1. Blix E. The admission CTG: is there any evidence for still using the test? Acta Obstet Gynecol Scand. 2013;92:613–9. 2. Ingemarsson I, Arulkumaran S, Ingemarsson E, Tambyraja RL, Ratnam SS. Admission test: a screening test for fetal distress in labor. Obstet Gynecol. 1986;68:800–6. 3. Ingemarsson I, Ingemarsson E. Foster€ overvakning med CTG. [Fetal monitoring with CTG] (In Swedish.) Stockholm: Studentlitteratur, 2006. 4. Lindqvist PG, Molin J. Does antenatal identification of small-for-gestational age fetuses significantly improve their outcome? Ultrasound Obstet Gynecol. 2005;25: 258–64.
Reply: Admission cardiotocography: practice based on evidence or assumptions and untested theories?
Dear Sir I thank Pelle Lindqvist for his interest in my commentary (1). The commentary (2) evaluated admission cardiotocography (CTG) from the perspective of clinical epidemiology – this is a part of evidence-based medicine. Lindqvist refers to his own experience, assumptions and untested theories indicating that admission CTG in all women improves outcomes in high-risk pregnancies. It is well known that it is difficult to draw conclusions from experiences on serious outcomes with very low frequencies. The subjective risk estimation is usually much higher than the objective (or epidemiological) risk estimation (3).
When there is disagreement about which procedures or treatments are best, it is important to have academic discussions about the topic and to review the research literature carefully. Today the evidence is interpreted differently, as the test is recommended for all women in Finland and Sweden, but only for high-risk women in Denmark, Iceland and Norway. In Great Britain, where the traditions for making evidence-based guidelines are stronger than in the Nordic countries, the guidelines for intrapartum care among healthy women do not recommend admission CTG in low-risk women (4). In my view, the current evidence does not
ª 2013 Nordic Federation of Societies of Obstetrics and Gynecology, Acta Obstetricia et Gynecologica Scandinavica 93 (2014) 428–432
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AOGS LE TT E R TO THE EDIT O R
Admission CTG test: “to be or not to be”
Sir Admission cardiotocography (CTG) tests have been used routinely since the early 1990s. The objective of the test is to identify a pathological CTG early after admission to the delivery unit. As it usually is taken during contractions, it functions as a stress test, allowing us to assess the fetal answer to the hypoxic stress related to contractions. In the publication “The admission CTG: is there any evidence for still using the test?”(1), Ellen Blix argues against the use of admission test because: (i) it does not predict delivery outcome, (ii) it has not been shown that admission tests lower poor outcome, and (iii) the high frequency of
(a)
abnormal CTG tracings (20–30%) causes an increased risk of operative delivery. Regarding points (i) and (ii), Skall vara referens till pa˚sta˚ende (i) och (ii) in her argument she starts by saying that “the admission test was introduced as a screening test for fetal distress in early labor,” after which she states that “the admission test was introduced as a screening test for fetal distress at labor.” Thereafter, there is a discussion of fundamentals in statistics and she summarizes the relation of the admission test and fetal and maternal outcome at delivery. None of the outcomes discussed by Ellen Blix actually assesses the admission test. The admission
(b)
(c)
Figure 1. Three different pathological admission CTG curves: all low-risk pregnancies, but delivered by immediate cesarean section after admission CTG. (a) Umbilical cord pH 6.88, uneventful follow-up. (b) Umbilical cord pH 6.85, 15% in weight deviation, uneventful follow-up. (c) Umbilical cord pH 7.26, 18% in weight deviation, Apgar 5, develops postnatal seizures and a severe hypoxic encephalopathy; the newborn died in the first postnatal week.
428
ª 2013 Nordic Federation of Societies of Obstetrics and Gynecology, Acta Obstetricia et Gynecologica Scandinavica 93 (2014) 428–432
Letter to the Editor
test is, and will always be, a final assessment of fetal health on admission to the delivery unit, and not a predictive test for later outcome. The goal is to lower the risk of severe asphyxia, neurological sequelae and intrauterine death among the very few fetuses already compromised on admission to the delivery unit. This is not investigated in her commentary. I refer to pathological CTG tracings taken on admission showing changes that might be difficult to auscultate (Figure 1). With reference to point (iii) the high number of abnormal CTG tracings is a major problem. In the original studies of the admission test there were only 1% pathological tracings and another 4% of non-reactive tracings (2). Later in Lund (nonpublished) the prevalence of pathological or non-reactive tracings was down to 2.9% (3). It is integral to the method that a fetus showing a non-reactive tracing should be stimulated to show potential for reactivity. If reactivity is shown, the tracing is normal. Ellen Blix has a point – and we have a problem – if there is a drift in CTG interpretations with an increasing rate of false abnormal CTGs causing unnecessary operative delivery. However, this problem should be solved by improving CTG interpretation and not by omitting the admission test. A bonus of the admission test is that it helps us to identify cases with preexisting neurological impairment or intrauterine fetal death (IUFD) immediately on admission to the delivery unit. A diagnosis of IUFD is tragic but the admission test makes it possible for the initiation of an adequate grieving process. If the diagnosis is made hours later, this will often initiate thoughts of negligence on the part of the delivery unit and at times unnecessary legal action. In addition, cases of IUFD during delivery are extremely rare today. Further, the admission CTG may give an indication of preexisting neurological impairment, which often would be impossible to detect with auscultation (Figure 1c). These rare cases are most often unidentified fetal growth restriction with low reserve capacity for tolerating contractions during delivery. It has been shown that awareness of growth restriction improves outcome substantially (4).
In my experience the admission test is an excellent way of identifying the few yearly cases with pathological CTG and IUFD on arrival at the delivery unit, which helps us to initiate the most adequate management and facilitate the grief process. It is, however, a major problem if there is a high prevalence of falsely abnormal interpretations of CTG, but this should solved by education and critical revision of CTG interpretations rather than by omitting the admission test.
Pelle G Lindqvist* Clintec, Obsterics and Gynecology, K57, Karolinska University Hospital, Stockholm, Sweden *Corresponding Author: Pelle G Lindqvist E-mail: [email protected] DOI: 10.1111/aogs.12297
References 1. Blix E. The admission CTG: is there any evidence for still using the test? Acta Obstet Gynecol Scand. 2013;92:613–9. 2. Ingemarsson I, Arulkumaran S, Ingemarsson E, Tambyraja RL, Ratnam SS. Admission test: a screening test for fetal distress in labor. Obstet Gynecol. 1986;68:800–6. 3. Ingemarsson I, Ingemarsson E. Foster€ overvakning med CTG. [Fetal monitoring with CTG] (In Swedish.) Stockholm: Studentlitteratur, 2006. 4. Lindqvist PG, Molin J. Does antenatal identification of small-for-gestational age fetuses significantly improve their outcome? Ultrasound Obstet Gynecol. 2005;25: 258–64.
Reply: Admission cardiotocography: practice based on evidence or assumptions and untested theories?
Dear Sir I thank Pelle Lindqvist for his interest in my commentary (1). The commentary (2) evaluated admission cardiotocography (CTG) from the perspective of clinical epidemiology – this is a part of evidence-based medicine. Lindqvist refers to his own experience, assumptions and untested theories indicating that admission CTG in all women improves outcomes in high-risk pregnancies. It is well known that it is difficult to draw conclusions from experiences on serious outcomes with very low frequencies. The subjective risk estimation is usually much higher than the objective (or epidemiological) risk estimation (3).
When there is disagreement about which procedures or treatments are best, it is important to have academic discussions about the topic and to review the research literature carefully. Today the evidence is interpreted differently, as the test is recommended for all women in Finland and Sweden, but only for high-risk women in Denmark, Iceland and Norway. In Great Britain, where the traditions for making evidence-based guidelines are stronger than in the Nordic countries, the guidelines for intrapartum care among healthy women do not recommend admission CTG in low-risk women (4). In my view, the current evidence does not
ª 2013 Nordic Federation of Societies of Obstetrics and Gynecology, Acta Obstetricia et Gynecologica Scandinavica 93 (2014) 428–432
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