Antepartum Fetal Surveillance: Aboubakr Elnashar


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Antepartum fetal surveillance

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Antepartum Fetal Surveillance: Aboubakr Elnashar

  1. 1. Aboubakr Elnashar
  2. 2. Aboubakr Elnashar
  3. 3. Fetal Neurodevelopment Function Center Week Tone cortex/subcortex 7.5-8.5 Movement cortex/nucle 9 Breathing i ventral surface of fourth ventricle 20-21 Fetal heart rate reactivity posterior hypothalamus/ medulla 24 Aboubakr Elnashar
  4. 4. Patterns of foetal activity 1.Fetal breathing movements 2.Gross body movements 3.Fine motor movements Aboubakr Elnashar
  5. 5. Fetal behavioral states (Nijhuis et al, 1982): • F1: quiescent state (quiet sleep) • F2: Frequent gross body movements • F3: Continuous eye movement. This state was disputed (Philia & James, 1990) • F4: Vigorous body movements & FHR accelerations Aboubakr Elnashar
  6. 6. During the last 10 w of pregnancy: F. breathing movements: 30% of the time Gross body movements: 10% of the time At term: Cycling between activity & quiescence occurs over a time span of 60 min Activity is highest in late evening FHR variation increases during fetal activity Accelerations are associated with f. body movements. Aboubakr Elnashar
  7. 7. Adaptations to hypoxia  Early 1.Reduced FHR reactivity 2.Absence of breathing movements  Late: 1. Reduced body movements and tone 2. Reduced liquor (renal hypoperfusion) Aboubakr Elnashar
  8. 8. Aboubakr Elnashar
  9. 9. The ideal test 1. Quick 2. Easy to perform 3. Interpreted results that are reproducible. 4. Clearly identify the compromised fetus at a stage at which intervention will improve the outcome 5. Not give an abnormal result for a healthy fetus.  Unfortunately, this ideal test does not yet exist! Aboubakr Elnashar
  10. 10. I. Fetal movements counting (FMC) II. Fetal heart rate recording 1.CTG 2.Non-Stress Test (NST) 3.Contraction StressTest (CST) or Oxytocin Challenge Test (OCT) 4.Nipple stimulation test 5.Vibroacoustic stimulation (VAS) 6.Computerized CTG III. Biophysical Profile (BPP) IV. Doppler Aboubakr Elnashar
  11. 11. I. Fetal movements counting (FMC) Idea: Sadovsky and Yaffee (1973) pre-eclamptic patients noticed decreased fetal movement prior to fetal demise. Aboubakr Elnashar
  12. 12. Women perceive most movement when lying down fewer when sitting and least while standing. Busy pregnant women: not concentrating on fetal activity: often report a misperception of RFM. Aboubakr Elnashar
  13. 13. important clinical sign: significant reduction or sudden change in movement The fetus may be in a state of sleep or the mother may be too busy to focus on fetal activity. Although fetal movements tend to plateau at 32 w, there is no reduction in the frequency of fetal movements in the late 3rd trimester. Aboubakr Elnashar
  14. 14. How to perform?. 1.One to Two Hours Method. The patient is asked to relax on her left side 30 min after eating. The patient should record the time that she starts the test and note each time the baby kicks. Normal: 3-5 Kicks within 60 min Normal: 10 within 60-75 minutes. Aboubakr Elnashar
  15. 15. Aboubakr Elnashar
  16. 16. 2. The Cardiff Count-to-Ten chart:  The patient records fetal movements during the course of usual daily activity.  warning signal: 12 hours without at least 10 perceived movements: patient should be evaluated and should undergo further testing e.g. NST. Aboubakr Elnashar
  17. 17. Advantages: 1. Inexpensive & noninvasive 2. An effective screening measure {reductions in fetal mortality from 8.7 deaths per 1,000 live births to 2.1 deaths per 1,000 live births}. Some authorities suggest that all pregnant patients, regardless of risk factors, be counseled about formal assessment of fetal movement. Aboubakr Elnashar
  18. 18. Disadvantages: 1. US studies: mother can feel up to 80% of movements seen on scan after 36 w, a mother may feel only 15% of movements. 2. No defined number of movements that must be felt, nor is it known over what time frame the testing should occur. Aboubakr Elnashar
  19. 19. 3. Routine daily FMC followed by appropriate action when movements are reduced offer no advantage over informal inquiry about movements during standard antenatal care & selective use of formal counting in high risk cases{B} (RCT of 68000 women). 4. Although the study did not rule out a beneficial effect of FMC, the policy would have to be used by 1250 women to prevent one perinatal death. Aboubakr Elnashar
  20. 20. Should fetal movements be counted routinely in a formal manner? insufficient evidence to recommend formal fetal movement counting using specified alarm limits (NICE) Women should be advised to be aware of their baby’s individual pattern of movements. If they are concerned about a reduction in or cessation of fetal movements after 28+0w, they should contact their doctor. and should not wait until the next day for assessment of fetal wellbeing. Aboubakr Elnashar
  21. 21. The effect of FMC in high-risk pregnancies is not known Prudent pay careful attention to their fetal movements. reduction or an alteration in the movements of their fetus should be offered some form of assessment of fetal well-being [E]. Aboubakr Elnashar
  22. 22. II. Fetal heart rate recording 1.CTG 2.NST 3.Contraction stress test 4.Nipple stimulation test 5.Acoustic stimulation test 6.Computerized CTG Aboubakr Elnashar
  23. 23. 1. Fetal heart rate tracings (CTG) METHOD Simultaneous recordings are performed by two separate transducers, one for FHR and second one for UC Aboubakr Elnashar
  24. 24. INTERPRETATION 1.Normal/Reassuring Trace  Baseline FHR: 110-150 b/m  Baseline variability: 10-25 b/m  At least 2 accelerations (>15 beats for> 15 sec in 20 min)  No decelerations. Aboubakr Elnashar
  25. 25. 2. Suspicious/Equivocal Trace.  Baseline FHR: 150-170 b/m or 100-110 b/m  Reduced baseline variability (5-10 b/m for >40 m)  Absence of accelerations for >40 m  Sporadic deceleration of any type.  absence of accelerations  diminished variability  late decelerations with weak spontaneous contractions. Aboubakr Elnashar
  26. 26. Aboubakr Elnashar
  27. 27. Abnormal/Pathological Trace -  Baseline FHR: <100 b/m or > 170 b/m  Silent Pattern (<5 b/m) for >40 min  Sinusoidal pattern (oscillation frequency = 2-5 cycles/min, amplitude of 5-15 b/m) for >40 m  No accelerations  No area of normal baseline variability  Repeated late, prolonged (> 1 minute) severe variable* (>40 b/m) decelerations.  *decelerations vary in depth, vary in duration and vary in timing relative to the uterine activity Aboubakr Elnashar
  28. 28. Tachycardia  Sinusoidal pattern  Late deceleration normal baseline rate at 120 bpm, absent baseline variability, no accelerations late decelerations Aboubakr Elnashar
  29. 29.  variable fetal heart rate decelerations. Reassuring shoulders (accelerations) are obvious before and after each deceleration. baseline tachycardia minimal variability. Aboubakr Elnashar
  30. 30. MANAGEMENT:  Normal/Reassuring Trace – repeat and/or estimate AFI if considered necessary acc to the clinical situation and indication for testing.  Suspicious/Equivocal Trace –  Continue for up to 60 min {determine the presence of fetal rest/activity cycles}.  Further evaluation acc to the cl situation e.g. fetal acoustic stimulation, AFI, BPP, Doppler blood velocity waveform.  Abnormal/Pathological Trace –  deliver if clinically appropriate.  Further evaluation/monitoring if not appropriate to deliver. Aboubakr Elnashar
  31. 31. Advantages: It is the most commonly performed antenatal test for fetal wellbeing. Quick Simple to perform Aboubakr Elnashar
  32. 32. 2. The Non-Stress Test (NST) (Hammacher et al, 1960) Idea: • FHR accelerations: linked closely with fetal movements {increased sympathetic output}. • The long term variability: {balance between sympathetic & parasympathetic tone} • The short term variability (baseline or bandwidth variability) {parasympathetic tone}. Aboubakr Elnashar
  33. 33. Steps: 1. left lateral recumbent position. 2. Place and adjust the external tocodynamometer and US transducer to obtain the best possible tracing. 3. Instruct the patient to record f movements on the monitor tracing using the event marker. 4. Observe the EFM tracing until the criteria for a reactive test are met (minimum of 20 min and maximum of 60 min). Aboubakr Elnashar
  34. 34.  In the event of lack of fetal movement, apply stimulation e.g. fetal acoustic stimulator.  Record any relevant clinical information on the EFM tracing e.g. BP T P loss of contact changes in maternal position. Aboubakr Elnashar
  35. 35. Interpretation:  Reactive: 2 accelerations of FHR in 20 min. Each acceleration 15 beat & lasts 15 sec.  Non-reactive: no accelerations in 40 min. Aboubakr Elnashar
  36. 36. •Reactive: increase of FHR to >15 beats/min for > 15 sec following fetal movements Reactive Aboubakr Elnashar
  37. 37. Antenatal maternal glucose administration: not to reduce non-reactive CTG (Cochrane , 2001) Manual fetal manipulation: not to reduce the incidence of non-reactive CTG. (Cochrane , 2001) Aboubakr Elnashar
  38. 38. Disadvantages: 1. Interpretation may be difficult & poor agreement between experts in assessing CTG 2. The predictive value of an abnormal NST for perinatal morbidity & mortality:<40% (Devoe et al, 1985) Aboubakr Elnashar
  39. 39. 3. No significant effect on perinatal outcome (MA of 13 trials) Trend towards increased perinatal mortality (SR of 4 RCT) (Cochrane library, 2001) NST should not be relied upon as the sole means of establishing fetal well-being {Ia} Aboubakr Elnashar
  40. 40. 3. The Contraction Stress Test (CST) or Oxytocin Challenge Test (OCT) 1972: First introduced by Ray 1975: Freeman introduced the parameters of contraction number and frequency to standardize the test. Aboubakr Elnashar
  41. 41. Idea: It is a test of the uteroplacental unit. If fetal oxygenation is marginal at rest, it will transiently worsen with uterine contractions: hypoxemia: late decelerations. If variable decelerations were seen, one should suspect oligohydramnios. Aboubakr Elnashar
  42. 42. Steps: Semi-fowlers position. If the patient is not having spontaneous contractions, pitocin is begun at 0.5-1.0 mU and increased /15-20 minutes until 3C/10 min. Aboubakr Elnashar
  43. 43. Interpretation: Negative: no decelerations with the 3 contractions in the 10 minute window. Positive: late decelerations with 50% or more of the contractions. Suspicious: intermittent late decelerations or severe variable deceleration. Unsatisfactory: <3 contractions or hyperstimulation. Aboubakr Elnashar
  44. 44. •Non-reactive NST followed by CST: mild late decelerations. Aboubakr Elnashar
  45. 45. CST: negative Aboubakr Elnashar
  46. 46. 1. Negative No deceleration 2. Positive transient decelerations Aboubakr Elnashar
  47. 47. Relative contraindications: 1. Preterm labor or certain patients at high risk of preterm labor 2. Preterm membrane rupture 3. History of extensive uterine surgery or classical cesarean delivery 4. Known placenta previa Aboubakr Elnashar
  48. 48. The role of this technique has yet to be established it has been associated with reports of fetal death in cases of unrecognized severe fetal compromise [E]. Aboubakr Elnashar
  49. 49. 4. Nipple stimulation test Intermittent nipple massage has the same goals. How to perform The women stimulate one breast, through their clothes, for 2 min and then to rest for 5 min. This cycle is repeated as necessary, but is interrupted whenever contractions began. Advantages Hyperstimulation is not more frequent than previously reported with CST. Average time: 45 min. Easy and quick method Aboubakr Elnashar
  50. 50. Sequence Of Events With Placental Insufficiency or Hypoxia 1. Positive CST= late deceleration in 50% of UC. 2. Non reactive NST= No HR acceleration 3. Cessation of fetal movement 4. Basal line tachycardia > 160 bpm 5. Basal line bradycardia <110 bpm Aboubakr Elnashar
  51. 51. 5. VIBROACOUSTIC STIMULATION (VAS) Idea: Vibroacoustic stimulator wakes a sleeping fetus: changing its behavioral state. How to perform: Artificial larynxes that generate sound pressure levels of approximately 80 to 100 decibels is applied in two or three one-second bursts to the maternal abdomen near the fetal head. Aboubakr Elnashar
  52. 52. Advantages: 1. Easy, relatively inexpensive way to shorten testing times and reduce the false-positive rates for NST & biophysical profiles. 2. Fetuses that respond to VAS with an acceleration on NST or a startle response on FBP: very low rates of death within one week of the test. 3. Decrease the incidence of non- reactive CTG and reducing the testing time (The Cochrane Database of Systematic Review, 2001) Aboubakr Elnashar
  53. 53. 6. Computerized CTG • To improve the objectivity of antenatal CTG • The program unlike conventional CTG, allows measurement of short term variability (STV). • STV=variation measured in 3.75 s epochs. • FHRV: better predictor of fetal compromise than the acceleration or decelerations. • Likelihood of metabolic acidaemia or IUFD can be calculated according to the STV. Aboubakr Elnashar
  54. 54. Aboubakr Elnashar
  55. 55. Conventional Vs computerized CTG 1.Fewer additional fetal tests 2.Less time in testing. 3.The study was not large enough to demonstrate any effect on perinatal morbidity or mortality. Aboubakr Elnashar
  56. 56. III. The Biophysical Profile (BPP) First described by Manning in 1980. Idea: Sequence of fetal deterioration 1. Late decelerations appear (CST) 2. Accelerations disappear (NST, BPP, CST) 3. Fetal breathing stops (BPP) 4. Fetal movement stops (BPP) 5. Fetal tone absent (BPP) 6. Amniotic fluid decreases {chronic hypoxia: redistribution of cardiac output away from the kidneys toward the brain}: AFV is a quick evaluation of long term uteroplacental function as in the late 2nd and all the 3rd trimester {AF is essentially fetal urine}. Aboubakr Elnashar
  57. 57. OBSERVATION CRITERIA FOR PRESENT CRITERIA FOR NEGATIVE Fetal Tone 1 episode of flexion- extension-flexion in 30 min No episodes of flexion- extension-flexion in 30 minutes Fetal Movement 3 gross body movements in30 min Less than 3 gross body movements in 30 minutes Fetal Breathing 1 episode of rhythmic breathing in 30 min No episodes of rhythmic breathing in 30 minutes Amniotic Fluid Volume One 2 centimeter pocket measured in two perpendicular planes A pocket measuring less than 2 centimeters NST Reactive test Non-reactive test Two points are given if the observation is present and zero points are given if it is absent. Aboubakr Elnashar
  58. 58. Interpretation: 8: reassuring. 6: equivocal: repeat within 24 h. 4 or less: positive test: strongly suggests preparing the patient for delivery. Aboubakr Elnashar
  59. 59. Modifications 1. BPP Manning (1990) NST AFV Fetal breathing. less cumbersome results are just as predictive. Aboubakr Elnashar
  60. 60. 2. Placental grading has been incorporated in the BPP to give an overall score out of 12 rather than 10. Aboubakr Elnashar
  61. 61. 3. The most powerful components: •AFI: indicator of long term uteroplacental function •NST: short term indicator of fetal acid-base status. assessment of fetal well-being using these two tools alone may well be as effective as formal BPP Aboubakr Elnashar
  62. 62.  Advantages: 1. In high-risk:  observational studies: effective  {good negative predictive value (99.9%) i.e. fetal death is rare in women with a normal FBP  rarely abnormal when Doppler findings were normal}. Aboubakr Elnashar
  63. 63. 2. In pre-labour rupture of the membranes {fetal breathing movements is reduced in the presence of chorioamnionitis} But sensitivity for abnormal BPP in the presence of chorioamnionitis is 25%[B]: value of BPP is limited Aboubakr Elnashar
  64. 64.  Disadvantages: 1. Difficult and time-consuming 2. False-positive rate: 70%: increased rates of unnecessary intervention. 3. Systematic review of five RCTs: failed to demonstrate any significant benefit of BPP on pregnancy outcome when compared to NST Aboubakr Elnashar
  65. 65. 4. In low risk: cannot be recommended for routine monitoring 5. In high Risk: positive predictive value of 35% (observational study) No enough evidence from RCTs (Cochrane Systematic Review, 2000).: cannot be recommended for routine monitoring for primary surveillance in SGA Aboubakr Elnashar
  66. 66. Statistical Characteristics of Selected Antepartum Fetal Tests Characteristic NST CST BPP Specificity Poor Average High Specificity High High High False-positive rate High High High False-negative rate Low Low Average Aboubakr Elnashar
  67. 67. V. Doppler A. Umbilical artery Doppler Idea: Umbilical Arterial Flow is normally of low resistance. In hypoxic states: relative placental hypoxia: reactive VC of umbilical artery: higher resistance: decrease in diastolic flow Aboubakr Elnashar
  68. 68. Doppler indices Aboubakr Elnashar
  69. 69.  Interpretation:  Resistance index  Enddiastolic flow  Systolic/diastolic ratio  Pulsatility index  Diastolic average ratio Aboubakr Elnashar
  70. 70. •Resistance index: Best ability to predict abnormal outcomes (RCOG,2002 Evidence level II)  Normal pregnancy: {progressive increase in end-diastolic velocity {growth& dilatation of the umbilical circulation}: Resistance index falls. Fetal growth restriction and/or PET: > 0.72 is outside the normal limits from 26 w. Aboubakr Elnashar
  71. 71. •End Diastolic flow In fetal growth restriction and/or preeclampsia: reduced, then absent (AED) or reversed (RED) in severe cases Absent or reversed: Fetal distress is almost certain: Immediate BPP or NST or Delivery may be indicated. Aboubakr Elnashar
  72. 72. •S/D Should be <3. Small increases in S/D= 3-5: chronic intrauterine disease manifest by IUGR. Not strictly useful: {1. low sensitivity. 2. Gestation age dependent}. Aboubakr Elnashar
  73. 73. Normal Absent Reversed Aboubakr Elnashar
  74. 74. RED Aboubakr Elnashar
  75. 75. Absent Reversed Aboubakr Elnashar
  76. 76. Advantages: 1. In low risk No benefit on mother or baby (The Cochrane Library, 2003) Aboubakr Elnashar
  77. 77. 2. In high risk:  Reduction of perinatal morbidity and mortality number of antenatal admissions inductions of labor resources compared with CTG (Grade A RCOG, 2002; The Cochrane Library, 2003)  Comparing FHR monitoring, FBP and umbilical artery Doppler: only umbilical artery Doppler had value in predicting poor perinatal outcomes in SGA Aboubakr Elnashar
  78. 78.  Frequency of monitoring in SGA fetuses with normal Doppler:  A 4-week U/S measurement interval was shown to be superior to a 2-week interval, in terms of reducing the false –positive rate (Owen et al, 2001).  Once/2w (Fortnightly) scans should be undertaken where 1. linear growth velocity is not maintained or 2. AC is below the third centile (IV) Aboubakr Elnashar
  79. 79. B. Middle cerebral artery peak systolic velocity (MCA-PSV) The most significant breakthrough in the surveillance of the potentially anemic fetus Based on: In fetal anemia: Enhanced fetal cardiac output and Decrease in blood viscosity: Increased blood flow velocity preferentially shunt blood to brain faster most pronounced MCA PSV Aboubakr Elnashar
  80. 80. Frequency •Initiated: 18 w •Repeated: every 1–2 w as the clinical situation MCA waveforms in an anemic fetus requiring serial transfusions for severe Rh (D) disease. The peak systolic velocities of 62, 50, and 61 cm per second (top to bottom) corresponded to fetal hematocrits of 19%, 44%, and 32%, before, at the time of, and a week after the first intravascular transfusion, respectively. Aboubakr Elnashar
  81. 81. Aboubakr Elnashar
  82. 82. Advantage More sensitive for predicting f anemia than the ΔOD450 (Recent studies) Alternative to serial amniocenteses Excellent noninvasive tool for the monitoring of f anemia. Aboubakr Elnashar
  83. 83. c. Uterine artery Doppler  limited use in predicting FGR and perinatal death (Grade A, RCOG,2002).  Abnormal uterine artery suggest: maternal cause for the growth restriction  Normal uterine artery Doppler suggest: fetal cause Aboubakr Elnashar
  84. 84. UAD: Normal UAD: notch, decreased diastolic flow Aboubakr Elnashar
  85. 85. Prediction of preeclampsia (Uterine Doppler velocimetry)  Persistence of a Diastolic Notch in uterine artery waveform after 24 w  Systolic/diastolic ratio >2.6  RI > 0.58 after 24 weeks. Systole Diastole Aboubakr Elnashar
  86. 86. Conclusions Aboubakr Elnashar
  87. 87. 1. CTG, must not form the sole basis for the assessment of the fetus. 2. Computerized CTG may well be more effective than standard CTG. 3. Formal assessment of the BPP does not appear to hold any advantage over assessment of liquor volume alone. 4. Where fetal growth restriction is suspected, fetal biometry and assessment of umbilical artery waveforms by Doppler ultrasonography should be incorporated. Aboubakr Elnashar
  88. 88. Aboubakr Elnashar Aboubakr Elnashar