Umbilical cord blood acid-base analysis at delivery
- Susan M Ramin, MD
Susan M Ramin, MD
- Section Editor — Obstetrics
- Professor of Obstetrics and Gynecology
- Baylor College of Medicine
Fetal acid-base balance can be assessed in a number of ways:
●Antepartum, by percutaneous umbilical cord blood sampling (see "Fetal blood sampling")
●Intrapartum, by fetal scalp blood sampling (see "Intrapartum fetal heart rate assessment", section on 'Fetal scalp blood sampling')
●Immediately after birth, by umbilical cord blood sampling
Information from umbilical cord blood sampling immediately after birth can be useful from medical and medicolegal perspectives since it provides insight into intrapartum fetal physiology. This topic will review basic concepts of fetal acid-base physiology and discuss the clinical use of umbilical cord acid-base analysis at delivery.
- Blechner JN. Maternal-fetal acid-base physiology. Clin Obstet Gynecol 1993; 36:3.
- Nageotte MP. Intrapartum fetal surveillance. In: Creasy & Resnik’s Maternal-Fetal Medicine Principles and Practice, 7th ed, Creasy, Resnik, Iams, Lockwood, Moore, Greene (Eds), Saunders, Philadelphia 2013. p.488.
- James EJ, Raye JR, Gresham EL, et al. Fetal oxygen consumption, carbon dioxide production, and glucose uptake in a chronic sheep preparation. Pediatrics 1972; 50:361.
- Tuuli MG, Stout MJ, Shanks A, et al. Umbilical cord arterial lactate compared with pH for predicting neonatal morbidity at term. Obstet Gynecol 2014; 124:756.
- Aarnoudse JG, Illsley NP, Penfold P, et al. Permeability of the human placenta to bicarbonate: in-vitro perfusion studies. Br J Obstet Gynaecol 1984; 91:1096.
- Cunningham FG, Leveno KJ, Bloom SL, et al. The newborn infant. In: Williams Obstetrics, 23rd ed, McGraw-Hill, New York 2010. p.590.
- Royal College of Obstetricians and Gynecologists, Royal College of Midwives, Royal College of Anaesthetists, Royal College of Paediatrics and Child Health: Safer childbirth. Minimum standards for the organisation and delivery of care in labour. Report of joint working party. RCOG Press, London 2007:46.
- American College of Obstetricians and Gynecologists (ACOG) and American Academy of Pediatrics (AAP). Neonatal encephalopathy and neurologic outcome, Second Edition. ACOG; Washington, DC 2014.
- Page FO, Martin JN, Palmer SM, et al. Correlation of neonatal acid-base status with Apgar scores and fetal heart rate tracings. Am J Obstet Gynecol 1986; 154:1306.
- Sykes GS, Molloy PM, Johnson P, et al. Do Apgar scores indicate asphyxia? Lancet 1982; 1:494.
- Silverman F, Suidan J, Wasserman J, et al. The Apgar score: is it enough? Obstet Gynecol 1985; 66:331.
- Low JA. The role of blood gas and acid-base assessment in the diagnosis of intrapartum fetal asphyxia. Am J Obstet Gynecol 1988; 159:1235.
- American College of Obstetricians and Gynecologists. Timing of umbilical cord clamping after birth. ACOG Committee Opinion 543, ACOG; 2012.
- ACOG Committee on Obstetric Practice. ACOG Committee Opinion No. 348, November 2006: Umbilical cord blood gas and acid-base analysis. Obstet Gynecol 2006; 108:1319.
- Armstrong L, Stenson B. Effect of delayed sampling on umbilical cord arterial and venous lactate and blood gases in clamped and unclamped vessels. Arch Dis Child Fetal Neonatal Ed 2006; 91:F342.
- Lievaart M, de Jong PA. Acid-base equilibrium in umbilical cord blood and time of cord clamping. Obstet Gynecol 1984; 63:44.
- Wiberg N, Källén K, Olofsson P. Delayed umbilical cord clamping at birth has effects on arterial and venous blood gases and lactate concentrations. BJOG 2008; 115:697.
- Beaulieu M, Lapointe Y, Vinet B. Stability of PO2, PCO2, and pH in fresh blood samples stored in a plastic syringe with low heparin in relation to various blood-gas and hematological parameters. Clin Biochem 1999; 32:101.
- Duerbeck NB, Chaffin DG, Seeds JW. A practical approach to umbilical artery pH and blood gas determinations. Obstet Gynecol 1992; 79:959.
- Sykes GS, Molloy PM. Effect of delays in collection or analysis on the results of umbilical cord blood measurements. Br J Obstet Gynaecol 1984; 91:989.
- Hilger JS, Holzman IR, Brown DR. Sequential changes in placental blood gases and pH during the hour following delivery. J Reprod Med 1981; 26:305.
- Strickland DM, Gilstrap LC 3rd, Hauth JC, Widmer K. Umbilical cord pH and PCO2: effect of interval from delivery to determination. Am J Obstet Gynecol 1984; 148:191.
- Lynn A, Beeby P. Cord and placenta arterial gas analysis: the accuracy of delayed sampling. Arch Dis Child Fetal Neonatal Ed 2007; 92:F281.
- Riley RJ, Johnson JW. Collecting and analyzing cord blood gases. Clin Obstet Gynecol 1993; 36:13.
- Nodwell A, Carmichael L, Ross M, Richardson B. Placental compared with umbilical cord blood to assess fetal blood gas and acid-base status. Obstet Gynecol 2005; 105:129.
- Malin GL, Morris RK, Khan KS. Strength of association between umbilical cord pH and perinatal and long term outcomes: systematic review and meta-analysis. BMJ 2010; 340:c1471.
- Cantu J, Szychowski JM, Xuelin L, et al. Predicting Fetal Acidemia Using Umbilical Venous Cord Gas Parameters. Obstet Gynecol 2014; :926.
- Westgate J, Garibaldi JM, Greene KR. Umbilical cord blood gas analysis at delivery: a time for quality data. Br J Obstet Gynaecol 1994; 101:1054.
- Georgieva A, Moulden M, Redman CW. Umbilical cord gases in relation to the neonatal condition: the EveREst plot. Eur J Obstet Gynecol Reprod Biol 2013; 168:155.
- Ramin SM, Gilstrap LC 3rd, Leveno KJ, et al. Umbilical artery acid-base status in the preterm infant. Obstet Gynecol 1989; 74:256.
- Dickinson JE, Eriksen NL, Meyer BA, Parisi VM. The effect of preterm birth on umbilical cord blood gases. Obstet Gynecol 1992; 79:575.
- Yeomans ER, Hauth JC, Gilstrap LC 3rd, Strickland DM. Umbilical cord pH, PCO2, and bicarbonate following uncomplicated term vaginal deliveries. Am J Obstet Gynecol 1985; 151:798.
- Victory R, Penava D, Da Silva O, et al. Umbilical cord pH and base excess values in relation to adverse outcome events for infants delivering at term. Am J Obstet Gynecol 2004; 191:2021.
- Helwig JT, Parer JT, Kilpatrick SJ, Laros RK Jr. Umbilical cord blood acid-base state: what is normal? Am J Obstet Gynecol 1996; 174:1807.
- Gregg AR, Weiner CP. "Normal" umbilical arterial and venous acid-base and blood gas values. Clin Obstet Gynecol 1993; 36:24.
- Andres RL, Saade G, Gilstrap LC, et al. Association between umbilical blood gas parameters and neonatal morbidity and death in neonates with pathologic fetal acidemia. Am J Obstet Gynecol 1999; 181:867.
- Gilstrap LC 3rd, Leveno KJ, Burris J, et al. Diagnosis of birth asphyxia on the basis of fetal pH, Apgar score, and newborn cerebral dysfunction. Am J Obstet Gynecol 1989; 161:825.
- Goldaber KG, Gilstrap LC 3rd. Correlations between obstetric clinical events and umbilical cord blood acid-base and blood gas values. Clin Obstet Gynecol 1993; 36:47.
- King TA, Jackson GL, Josey AS, et al. The effect of profound umbilical artery acidemia in term neonates admitted to a newborn nursery. J Pediatr 1998; 132:624.
- Sehdev HM, Stamilio DM, Macones GA, et al. Predictive factors for neonatal morbidity in neonates with an umbilical arterial cord pH less than 7.00. Am J Obstet Gynecol 1997; 177:1030.
- Winkler CL, Hauth JC, Tucker JM, et al. Neonatal complications at term as related to the degree of umbilical artery acidemia. Am J Obstet Gynecol 1991; 164:637.
- Goldaber KG, Gilstrap LC 3rd, Leveno KJ, et al. Pathologic fetal acidemia. Obstet Gynecol 1991; 78:1103.
- Agrawal SK, Doucette F, Gratton R, et al. Intrapartum computerized fetal heart rate parameters and metabolic acidosis at birth. Obstet Gynecol 2003; 102:731.
- Graham EM, Ruis KA, Hartman AL, et al. A systematic review of the role of intrapartum hypoxia-ischemia in the causation of neonatal encephalopathy. Am J Obstet Gynecol 2008; 199:587.
- Sameshima H, Ikenoue T. Predictive value of late decelerations for fetal acidemia in unselective low-risk pregnancies. Am J Perinatol 2005; 22:19.
- Sameshima H, Ikenoue T, Ikeda T, et al. Unselected low-risk pregnancies and the effect of continuous intrapartum fetal heart rate monitoring on umbilical blood gases and cerebral palsy. Am J Obstet Gynecol 2004; 190:118.
- Cahill AG, Roehl KA, Odibo AO, Macones GA. Association and prediction of neonatal acidemia. Am J Obstet Gynecol 2012; 207:206.e1.
- Yeh P, Emary K, Impey L. The relationship between umbilical cord arterial pH and serious adverse neonatal outcome: analysis of 51,519 consecutive validated samples. BJOG 2012; 119:824.
- Hafström M, Ehnberg S, Blad S, et al. Developmental outcome at 6.5 years after acidosis in term newborns: a population-based study. Pediatrics 2012; 129:e1501.
- Low JA, Panagiotopoulos C, Derrick EJ. Newborn complications after intrapartum asphyxia with metabolic acidosis in the term fetus. Am J Obstet Gynecol 1994; 170:1081.
- Casey BM, Goldaber KG, McIntire DD, Leveno KJ. Outcomes among term infants when two-hour postnatal pH is compared with pH at delivery. Am J Obstet Gynecol 2001; 184:447.
- Low JA, Lindsay BG, Derrick EJ. Threshold of metabolic acidosis associated with newborn complications. Am J Obstet Gynecol 1997; 177:1391.
- Ross MG, Gala R. Use of umbilical artery base excess: algorithm for the timing of hypoxic injury. Am J Obstet Gynecol 2002; 187:1.
- Low JA. Determining the contribution of asphyxia to brain damage in the neonate. J Obstet Gynaecol Res 2004; 30:276.
- Chauhan SP, Hendrix NW, Magann EF, et al. Neonatal organ dysfunction among newborns at gestational age 34 weeks and umbilical arterial pH<7.00. J Matern Fetal Neonatal Med 2005; 17:261.
- White CR, Doherty DA, Henderson JJ, et al. Accurate prediction of hypoxic-ischaemic encephalopathy at delivery: a cohort study. J Matern Fetal Neonatal Med 2012; 25:1653.
- FETAL ACID-BASE PHYSIOLOGY
- Acids and buffers
- Differences from postnatal acid-base physiology
- INDICATIONS FOR FETAL ACID-BASE ANALYSIS
- TEST RESULTS
- Normal pH, blood gas, and buffer values
- Base deficit (negative base excess)
- Lactate levels
- SUMMARY AND RECOMMENDATIONS