Re: Cerebroplacental ratio in predicting adverse perinatal
outcome: a meta-analysis of individual participant data
Dear Sir:
We read with interest the study by Vollgraff Heidweiller-Schreurs et
al1 in which the authors compare the abilities of the
umbilical Doppler, middle cerebral Doppler and cerebroplacental ratio
(CPR) for the prediction of adverse perinatal outcome (APO). We would
like to congratulate the authors for this collaborative study and also
for the CPR IPD initiative. However, we disagree with their conclusions
and methodology, upon which we would like to make several comments:
First and foremost, the main diagnostic performance of CPR relies on the
ability to detect compromised fetuses that are unable to stand the
stress of labor2. However, in the absence of
contractions, even endangered fetuses with abnormal Doppler may be
delivered with a good perinatal outcome. Second, CPR performance is
strikingly dependent on the interval to labor, decreasing considerably
after 15 days. If we take into account that beyond the appropriate
performance range Doppler techniques with different abilities may seem
to be equally accurate, the information about the interval becomes
crucially important. Third, the possibility of APO depends on the kind
of labor onset. As a consequence, inductions with poor Bishop score are
more likely to present acidosis and APO than deliveries with spontaneous
onset and good obstetrics conditions4. All these
issues imply that in order to perform appropriate comparisons between
different Doppler techniques, cases with elective cesarean sections and
higher intervals to labor should be discarded. Moreover, the type of
labor onset should be taken into account. However, as far as we are
concerned, none of this was done. Last but not least, when preterm
fetuses are studied, admission to pediatric care can be the result not
only of hypoxia, but also of prematurity. Consequently, considering that
in this scenario intrapartum and neonatal pH become the only accurate
data to establish a clear diagnosis of acidosis, these parameters should
be homogeneous, as they should be using similar pH thresholds.
Unfortunately, this information was not provided.
Overlapping ROC curves may be the result of a similar performance
between the studied parameters. However, considering the above-mentioned
aspects, they might also be the result of biased comparisons performed
out of the appropriate performance range. While the findings of this
meta-analysis do not support the use of CPR out of a research protocol,
we would still like to consider that further research is needed to reach
such a conclusion, and that CPR so far remains a poor predictor, but the
best individual predictor of APO.
José Morales-Roselló*/**, Gabriela Loscalzo*, Silvia Buongiorno*,
Vaidilė Jakaitė*, Alfredo Perales-Marín*/**
*Servicio de Obstetricia, Hospital Universitario y Politécnico La Fe,
Valencia, Spain, and **Departamento de Pediatría, Obstetricia y
Ginecología, Universidad de Valencia, Valencia, Spain.
REFERENCES
1. Vollgraff Heidweiller-Schreurs CA, van Osch IR, Heymans MW,
Ganzevoort W, Schoonmade LJ, Bax CJ, Mol BWJ, de Groot CJ, Bossuyt PM,
de Boer MA; CPR IPD Study Group.
Cerebroplacental
ratio in predicting adverse perinatal outcome: a meta-analysis of
individual participant data. BJOG. 2020 May 3. doi:
10.1111/1471-0528.16287.
2. Khalil AA, Morales-Rosello J, Morlando M, Hannan H, Bhide A,
Papageorghiou A, Thilaganathan B.
Is fetal
cerebroplacental ratio an independent predictor of intrapartum fetal
compromise and neonatal unit admission? Am J Obstet Gynecol. 2015
Jul;213(1):54.e1-54.e10.
3.
Akolekar
R,
Syngelaki
A,
Gallo
DM,
Poon
LC,
Nicolaides
KH. Umbilical and fetal middle cerebral artery Doppler at 35-37 weeks’
gestation in the prediction of adverse perinatal outcome.
Ultrasound Obstet
Gynecol. 2015 Jul;46(1):82-92.
4. Garcia-Simon R, Figueras F, Savchev S, Fabre E, Gratacos E, Oros D.
Cervical condition
and fetal cerebral Doppler as determinants of adverse perinatal outcome
after labor induction for late-onset small-for-gestational-age fetuses.
Ultrasound Obstet Gynecol. 2015 Dec;46(6):713-7.