Delayed cord clamping for at least 60 s in both term and preterm babies is a major recent change in clinical care. Delayed cord clamping has several effects on other possible interventions. One of these is the effect of delayed cord clamping on umbilical artery gas analysis. When indicated, umbilical artery gas analysis can safely be done either with early cord clamping or, probably most of the times it is necessary, during delayed cord clamping with the cord still unclamped. Paired blood samples (one from the umbilical artery and one from the umbilical vein) can be taken from the pulsating and unclamped cord, immediately after birth, during delayed cord clamping, without any effect on either the accuracy of umbilical artery gas analysis or the transfusion of blood through delayed cord clamping. Umbilical artery gas analysis should instead not be done after delayed cord clamping, since delayed cord clamping alters several acid-based parameters and lactate values.
Background: Recently, the literature suggested that placental transfusion facilitated by delayed cord clamping (DCC), besides having benefits on hematological parameters, might improve the infants' brain development.Objective: The present review primarily evaluates the Ages and Stages Questionnaire (ASQ) total score mean difference (MD) at long-term follow-up (≥4 months) comparing DCC (>90 or >180 s) to early cord clamping (ECC). Secondary aims consisted of evaluating the ASQ domains' MD and the results obtained from other methods adopted to evaluate the infants' neurodevelopment.Methods: MEDLINE, Scopus, Cochrane, and ClinicalTrials.gov databases were searched (up to 2nd November 2020) for systematic review and meta-analysis. All randomized controlled trials (RCTs) of term singleton gestations received DCC or ECC. Multiple pregnancies, pre-term delivery, non-randomized studies, and articles in languages other than English were excluded. The included studies were assessed for bias and quality. ASQ data were pooled stratified by time to follow up.Results: This meta-analysis of 4 articles from 3 RCTs includes 765 infants with four-month follow-up and 672 with 12 months follow-up. Primary aim (ASQ total score) pooled analysis was possible only for 12 months follow-up, and no differences were found between DCC and ECC (MD 1.1; CI 95: −5.1; 7.3). DCC approach significantly improves infants' communication domains (MD 0.6; CI 95: 0.1; 1.1) and personal-social assessed (MD 1.0; CI 95: 0.3; 1.6) through ASQ at 12 months follow-up. Surprisingly, the four-month ASQ personal social domain (MD −1.6; CI 95: −2.8; −0.4) seems to be significantly lower in the DCC group than in the ECC group.Conclusions: DCC, a simple, non-interventional, and cost-effective approach, might improve the long-term infants' neurological outcome. Single-blinding and limited studies number were the main limitations. Further research should be performed to confirm these observations, ideally with RCTs adopting standard methods to assess infants' neurodevelopment.Trial registration: NCT01245296, NCT01581489, NCT02222805, NCT01620008, IRCT201702066807N19, and NCT02727517
Timing of cord clamping for blood gas analysis is of paramount importanceSir,We thank Prof. Di Tommaso and Vannuccini for their interest in our article. 1,2 We congratulate their group for the study "Blood gas values in clamped and unclamped umbilical cord at birth". 3 In their prospective observational study, published in 2014, 46 patients delivered vaginally at term; for each patient, cord blood gas analysis was performed after blood collection had been carried out in two different ways. The first two blood samples, arterial and venous, were obtained from the unclamped cord within 90 seconds from birth.After that, two other samples were taken from a 10-cm segment of a double-clamped cord. No significant differences were observed on arterial pH, pO 2 , pCO 2 , SaO 2 or hemoglobin concentration (ctHb) between the samples obtained within 90 seconds from birth and the clamped samples analyzed immediately after the previous sampling.In contrast, the venous SaO 2 , ctHb and BE turned out to be significantly different between the unclamped and clamped cord, although pH, pO 2 and pCO 2 were comparable.We apologize for not having cited their study, 3 which actually reinforces our hypothesis with experimental data. Di Tommaso et al demonstrate a statistically significant difference between the arterial BE by comparing the two methods. 3 The same trend toward a higher (ie, less negative) BE in the unclamped samples is present in the venous cohort. There may be a slight variation in the interpretation of these data. While Di Tommaso et al give main importance to the difference between the two techniques of umbilical cord blood collection, we instead give priority to the difference in timing of blood collection. In our opinion, timing is a crucial issue, especially in newborns at risk of intrapartum asphyxia. Timing of blood collection explains why the median BE level is higher in unclamped samples than in clamped ones. Since the blood collection in unclamped cords was performed within 90 seconds after birth, the BE correlates more closely with the intrapartum cord gas status. After this lapse of time, two variables may influence the efficacy of the cord blood gases: sampling after the onset of newborn's breathing 4 or sampling after a condition of hidden acidosis has been established in the newborn. 5Obviously, these slight changes in cord blood gases at birth may have a higher impact in those fetuses who suffered from a hypoxic stress during labor. We once again congratulate Di Tommaso et al on their important work, 3 and for the opportunity to even better delineate our clinical correlations.We therefore suggest performing cord blood sampling for gas analysis as soon as possible after birth. Further experimental studies are needed to establish the exact timing, and to evaluate whether best timing is even before onset of breathing. Surely, the technique of blood collection from the intact (unclamped) and still pulsating umbilical cord is a suitable method in clinical practice. 1. Di Tommaso M, Vannuccini S. Is pulsating co...
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