Overview of antepartum fetal surveillance
- Caroline Signore, MD, MPH
Caroline Signore, MD, MPH
- Program Officer/Project Scientist
- Pregnancy and Perinatology Branch
- Eunice Kennedy Shriver National Institute of Child Health and Human Development
- Catherine Spong, MD
Catherine Spong, MD
- Bethesda, Maryland
The goal of antepartum fetal assessment is to both identify fetuses at risk of intrauterine death or other complications of intrauterine asphyxia and intervene to prevent these adverse outcomes, if possible. The main techniques for fetal assessment are the nonstress test, biophysical profile, modified biophysical profile, contraction stress test, and fetal movement count. Assessment of amniotic fluid volume and Doppler velocimetry provide additional information about fetal status. Despite widespread use of these techniques, there is limited evidence to guide their optimal use or to demonstrate their effectiveness for improving perinatal outcomes.
This topic will provide an overview of antepartum fetal assessment. Detailed discussions of the various techniques and their use in specific clinical settings are available separately (see individual topic reviews).
PHYSIOLOGICAL BASIS FOR FETAL TESTING
Antepartum testing is based on the premise that the fetus responds to hypoxemia with a detectable sequence of biophysical changes, beginning with signs of physiological adaptation and potentially ending with signs of physiological decompensation (figure 1) [1,2]. Studies in chronic animal models support this premise by demonstrating that fetal biophysical activities (eg, heart rate, movement) are sensitive to fetal oxygenation and pH levels, and changes in fetal biophysical activities occur in response to hypoxemia and acidemia . However, fetal biophysical parameters can be affected by factors unrelated to hypoxemia, such as gestational age, maternal medication/smoking, fetal sleep-wake cycles, and fetal disease/anomalies.
Periodic fetal antepartum testing rarely identifies fetuses at risk of death from a sudden insult, such as complete placental abruption, and thus does not provide an opportunity for intervention to prevent these deaths.
Antepartum fetal surveillance has had an established role in obstetrical practice since the 1970s , although its ability to improve pregnancy outcome has not been evaluated by large, well-designed randomized trials . Efficacy is based primarily on two lines of evidence: (1) observational studies that reported lower rates of fetal death in pregnancies that underwent fetal testing than among historic controls with the same indication for testing but no fetal testing and (2) the same or lower rates of fetal death in tested pregnancies (primarily high risk) than in a contemporary untested general obstetrical population (primarily low risk) [6-10].
- Martin CB Jr. Normal fetal physiology and behavior, and adaptive responses with hypoxemia. Semin Perinatol 2008; 32:239.
- Baschat AA, Gembruch U, Harman CR. The sequence of changes in Doppler and biophysical parameters as severe fetal growth restriction worsens. Ultrasound Obstet Gynecol 2001; 18:571.
- Bocking AD. The relationship between heart rate and asphyxia in the animal fetus. Clin Invest Med 1993; 16:166.
- Evertson LR, Gauthier RJ, Schifrin BS, Paul RH. Antepartum fetal heart rate testing. I. Evolution of the nonstress test. Am J Obstet Gynecol 1979; 133:29.
- Devoe LD. Antenatal fetal assessment: contraction stress test, nonstress test, vibroacoustic stimulation, amniotic fluid volume, biophysical profile, and modified biophysical profile--an overview. Semin Perinatol 2008; 32:247.
- Freeman RK, Anderson G, Dorchester W. A prospective multi-institutional study of antepartum fetal heart rate monitoring. I. Risk of perinatal mortality and morbidity according to antepartum fetal heart rate test results. Am J Obstet Gynecol 1982; 143:771.
- Miller DA, Rabello YA, Paul RH. The modified biophysical profile: antepartum testing in the 1990s. Am J Obstet Gynecol 1996; 174:812.
- Clark SL, Sabey P, Jolley K. Nonstress testing with acoustic stimulation and amniotic fluid volume assessment: 5973 tests without unexpected fetal death. Am J Obstet Gynecol 1989; 160:694.
- Nageotte MP, Towers CV, Asrat T, Freeman RK. Perinatal outcome with the modified biophysical profile. Am J Obstet Gynecol 1994; 170:1672.
- Manning FA, Morrison I, Harman CR, et al. Fetal assessment based on fetal biophysical profile scoring: experience in 19,221 referred high-risk pregnancies. II. An analysis of false-negative fetal deaths. Am J Obstet Gynecol 1987; 157:880.
- Practice bulletin no. 145: antepartum fetal surveillance. Obstet Gynecol 2014; 124:182.
- Goetzl L. Adverse pregnancy outcomes after abnormal first-trimester screening for aneuploidy. Clin Lab Med 2010; 30:613.
- Gagnon A, Wilson RD, Audibert F, et al. Obstetrical complications associated with abnormal maternal serum markers analytes. J Obstet Gynaecol Can 2008; 30:918.
- Frey HA, Odibo AO, Dicke JM, et al. Stillbirth risk among fetuses with ultrasound-detected isolated congenital anomalies. Obstet Gynecol 2014; 124:91.
- Bocking AD. Assessment of fetal heart rate and fetal movements in detecting oxygen deprivation in-utero. Eur J Obstet Gynecol Reprod Biol 2003; 110 Suppl 1:S108.
- Itskovitz J, Goetzman BW, Rudolph AM. The mechanism of late deceleration of the heart rate and its relationship to oxygenation in normoxemic and chronically hypoxemic fetal lambs. Am J Obstet Gynecol 1982; 142:66.
- Pose SV, Castillo JB, Nora-Rojas EO, et al. Test of fetal tolerance to induce uterine contractions for the diagnosis of chronic distress. In: Perinatal Factors Affecting Human Development, p 96. Washington, DC, Pan American Health Organization, 1969.
- Freeman RK, Anderson G, Dorchester W. A prospective multi-institutional study of antepartum fetal heart rate monitoring. II. Contraction stress test versus nonstress test for primary surveillance. Am J Obstet Gynecol 1982; 143:778.
- Rochard F, Schifrin BS, Goupil F, et al. Nonstressed fetal heart rate monitoring in the antepartum period. Am J Obstet Gynecol 1976; 126:699.
- Manning FA, Platt LD, Sipos L. Antepartum fetal evaluation: development of a fetal biophysical profile. Am J Obstet Gynecol 1980; 136:787.
- Thompson RS, Trudinger BJ. Doppler waveform pulsatility index and resistance, pressure and flow in the umbilical placental circulation: an investigation using a mathematical model. Ultrasound Med Biol 1990; 16:449.
- Hecher K, Bilardo CM, Stigter RH, et al. Monitoring of fetuses with intrauterine growth restriction: a longitudinal study. Ultrasound Obstet Gynecol 2001; 18:564.
- Ferrazzi E, Bozzo M, Rigano S, et al. Temporal sequence of abnormal Doppler changes in the peripheral and central circulatory systems of the severely growth-restricted fetus. Ultrasound Obstet Gynecol 2002; 19:140.
- al-Ghazali W, Chita SK, Chapman MG, Allan LD. Evidence of redistribution of cardiac output in asymmetrical growth retardation. Br J Obstet Gynaecol 1989; 96:697.
- Nicolaides KH, Bilardo CM, Soothill PW, Campbell S. Absence of end diastolic frequencies in umbilical artery: a sign of fetal hypoxia and acidosis. BMJ 1988; 297:1026.
- Weiner CP. The relationship between the umbilical artery systolic/diastolic ratio and umbilical blood gas measurements in specimens obtained by cordocentesis. Am J Obstet Gynecol 1990; 162:1198.
- Kontopoulos EV, Vintzileos AM. Condition-specific antepartum fetal testing. Am J Obstet Gynecol 2004; 191:1546.
- Gudmundsson S, Marsal K. Umbilical and uteroplacental blood flow velocity waveforms in pregnancies with fetal growth retardation. Eur J Obstet Gynecol Reprod Biol 1988; 27:187.
- Giles WB, Trudinger BJ, Baird PJ. Fetal umbilical artery flow velocity waveforms and placental resistance: pathological correlation. Br J Obstet Gynaecol 1985; 92:31.
- Karsdorp VH, van Vugt JM, van Geijn HP, et al. Clinical significance of absent or reversed end diastolic velocity waveforms in umbilical artery. Lancet 1994; 344:1664.
- Alfirevic Z, Stampalija T, Gyte GM. Fetal and umbilical Doppler ultrasound in high-risk pregnancies. Cochrane Database Syst Rev 2013; 11:CD007529.
- Alfirevic Z, Stampalija T, Medley N. Fetal and umbilical Doppler ultrasound in normal pregnancy. Cochrane Database Syst Rev 2015; 4:CD001450.
- Picklesimer AH, Oepkes D, Moise KJ Jr, et al. Determinants of the middle cerebral artery peak systolic velocity in the human fetus. Am J Obstet Gynecol 2007; 197:526.e1.
- Mari G, Hanif F, Kruger M, et al. Middle cerebral artery peak systolic velocity: a new Doppler parameter in the assessment of growth-restricted fetuses. Ultrasound Obstet Gynecol 2007; 29:310.
- Johnson P, Stojilkovic T, Sarkar P. Middle cerebral artery Doppler in severe intrauterine growth restriction. Ultrasound Obstet Gynecol 2001; 17:416.
- Baschat AA, Gembruch U, Reiss I, et al. Relationship between arterial and venous Doppler and perinatal outcome in fetal growth restriction. Ultrasound Obstet Gynecol 2000; 16:407.
- Kiserud T, Kessler J, Ebbing C, Rasmussen S. Ductus venosus shunting in growth-restricted fetuses and the effect of umbilical circulatory compromise. Ultrasound Obstet Gynecol 2006; 28:143.
- Kiserud T, Eik-Nes SH, Blaas HG, et al. Ductus venosus blood velocity and the umbilical circulation in the seriously growth-retarded fetus. Ultrasound Obstet Gynecol 1994; 4:109.
- Gudmundsson S, Korszun P, Olofsson P, Dubiel M. New score indicating placental vascular resistance. Acta Obstet Gynecol Scand 2003; 82:807.
- Hernandez-Andrade E, Brodszki J, Lingman G, et al. Uterine artery score and perinatal outcome. Ultrasound Obstet Gynecol 2002; 19:438.
- Soregaroli M, Valcamonico A, Scalvi L, et al. Late normalisation of uterine artery velocimetry in high risk pregnancy. Eur J Obstet Gynecol Reprod Biol 2001; 95:42.
- Papageorghiou AT, Yu CK, Cicero S, et al. Second-trimester uterine artery Doppler screening in unselected populations: a review. J Matern Fetal Neonatal Med 2002; 12:78.
- Bishop EH. Fetal acceleration test. Am J Obstet Gynecol 1981; 141:905.
- Society for Maternal-Fetal Medicine Publications Committee, Berkley E, Chauhan SP, Abuhamad A. Doppler assessment of the fetus with intrauterine growth restriction. Am J Obstet Gynecol 2012; 206:300.
- Morris RK, Malin G, Robson SC, et al. Fetal umbilical artery Doppler to predict compromise of fetal/neonatal wellbeing in a high-risk population: systematic review and bivariate meta-analysis. Ultrasound Obstet Gynecol 2011; 37:135.
- Gardosi J, Madurasinghe V, Williams M, et al. Maternal and fetal risk factors for stillbirth: population based study. BMJ 2013; 346:f108.
- Slomka C, Phelan JP. Pregnancy outcome in the patient with a nonreactive nonstress test and a positive contraction stress test. Am J Obstet Gynecol 1981; 139:11.
- Mathews TJ, MacDorman MF. Infant mortality statistics from the 2004 period linked birth/infant death data set. Natl Vital Stat Rep 2007; 55:1.
- PHYSIOLOGICAL BASIS FOR FETAL TESTING
- INDICATIONS FOR FETAL SURVEILLANCE
- Possible indications for antenatal testing
- FETAL ASSESSMENT TECHNIQUES
- Fetal movement counting
- Contraction stress test
- Nonstress test
- Biophysical profile
- Amniotic fluid volume
- Doppler velocimetry
- - Umbilical artery
- - Middle cerebral artery
- - Fetal veins
- - Uterine artery
- CHOICE OF TEST
- DURATION AND FREQUENCY
- MANAGEMENT OF ABNORMAL TEST RESULTS
- COSTS AND BENEFITS
- SUMMARY AND RECOMMENDATIONS