Intrapartum fetal monitoring for undergraduate


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undergraduate course lectures in Obstetrics&Gynecology, Faculty of medicine,Zagazig University

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Intrapartum fetal monitoring for undergraduate

  2. 2. The three unique risk factors for fetus during laborFactor of uterine contractionFactor of cord accidentFactor of head compression
  3. 3. Factor of uterine contractionLet us see what happen to oxygenation and blood supply of the fetal brain during a uterine contraction?
  4. 4. De-oxy-Hb 0.79micromol/100Gm of brainOxy –Hb 0.19 0.79micromol/100Gm of brainCerebralO2 saturation 9%Cerebral blood volume 0.33 ml/100Gm ofIn spite of this slightly worrying picture,Nothing harmful effect happen iffetus is healthylabor contraction are normalPlacenta has adequate reserve
  5. 5. Fetal distress, birth asphxia are likely to occur ifThe fetus is already compromised antenatally---even with normal uterine contractionThe uterine contraction are exaggerated------even with healthy fetus and adequate placental reserve
  6. 6. Factor of cord accidentOnly during labor cord prolaps ,presentation and entanglements (occult or overt) become apparent either by compression or stretch secondary to uterine contraction
  7. 7. Factor of head compressionSome degree of compression is inevitable during normal labor ButExcessive compression over long period causing supermouldingas in obstructed labormay cause fetal hypoxia
  8. 8. Methods available for fetal monitering in labor Intermittent auscultationCTG Fetal electrocardiographyScalp stimulation Vibroacoustic stimulationFetal scalp sampling  PH determinationFetal pulse oximetry
  9. 9. Important definationsHypoxia: Decreased po2 level in tissues.Hypoxima: Decreased po2 level in blood.Acidosis: Decreased PH in tissues.Acidemia: Decreased PH in blood.Ashyxia: Hypoxia with acidosis.
  10. 10. Aim of intrapertum fetal monitering 1- to detect the earliest stages of hypoxia or (hypoxic acidemia ) so therapy can be directed to prevent asphyxia and asphyxial damage 2-To Improve perinatal morbidity & mortality
  11. 11. What is Cardiotocography(CTG)?It is a paper record of the continuous FHR blotted simultaneously with a record of uterine activityUltrasound (cardio) transducerTocotransducer
  12. 12. External monitoringDoppler ultrasound transducer FHRTocotransducer(contraction)
  13. 13. Internal monitoring
  14. 14. What is ‘’Admission test ‘’?Ideally every fetus every fetus should be screened by CTG for a short period (20 min) right on admission in labor.From nature of the trace determine Intensity of monitoring “Whether the case should be monitored clinically or by CTG”Duration and frequency of monitoring “Whether the case should be covered by CTG continuously or intermittently”
  15. 15. Interpreting FHR trace4 components  Base line FHR  Baseline variability  Accelerations  Decelerations
  16. 16. Baseline FHRThe dominant reading taken ≥10 minNormal baseline FHR 110-160(pbm)Controlled byatrialpacemaker
  17. 17. Tachycardia FHR>160 bpm
  18. 18. Baseline bradycardia FHR<110bpm
  19. 19. Baseline varibilityThe Oscaltatory pattern of FHR when recorded on a graph.Short term(beat t0 beat) is the fluctuation of HR over short intervalLong termis the fluctuation over long interval(≥2 min)Indicates mature fetal neurologic system
  20. 20. Baseline varibilityShort term variability(scalp electrode)Long term variability defined as 3-5 cycle/min
  21. 21. Baseline varibility
  22. 22. No variability (0-2 ครั้ง/นาที) Minimal variability (3-4 ครั้ง/นาที)Moderate variability (11-25ครั้ง/นาที)Mark variability (>25 ครั้ง/นาที)
  23. 23. Changes in fetal HRPeroidic changes: Occur with contractionEpisodic changes (non peroidic):do not occur with contraction
  24. 24. AccelarationIncrease in FHR with contraction or with other activitiesCan be periodic or episodicIncrease15pbmlasting 15 secReturn to base line <2 min
  25. 25. Accelaration
  26. 26. Decelerations DecelerationsTransient slowing ofFHR below thebaseline levelmore than 15 bpmand lasting for 15 sec.or more.
  27. 27. Early Decelerations Uniform Synchronous with contraction (mirror image) Rarely fall below 110 (pbm) Due to head compression Should not be disregardedif they appear early in labor or Antenatal.
  28. 28. Early Decelerations
  29. 29. Late DecelerationUniformStart after peak of contractionAssociated with decreasedVariabilityReflect a baroreceptorresponseIndicate fetal hypoxia
  30. 30. Late Deceleration
  31. 31. Repetitive late decelrationincreases risk ofUmbilical artery acidosisApgar score < 7 at 5 msCerebral palsyIf associated withdecrease or loss ofvariability
  32. 32. Variable Deceleration (the most common type)Varible in appearance and Timing.May be assoicated with increased variability .Reflect umbilical cord compres Observed in up to 50% of NSTs compression• Of no clinical significance if non recurrent.
  33. 33. Variable Deceleration
  34. 34. Prolonged Deceleration deceleration A deceleration that lasts more than 90 seconds (but less than 10 minutes) Drop in FHR of 30 bpm or More Reduction in O2 transfer to placenta. Associated with poor neonatal outcome
  35. 35. Prolonged Deceleration
  36. 36. Sinusoidal pattern Regular Oscillation of the Baseline long-term Variability resembling a Sine wave ,with no beat to -beat Variability. Has fixed cycle of 3-5 pbm with amplitude of 5-15 bpm and above but not below the baseline. Should be viewed with suspicion as poor outcome has been seen (eg Feto-maternal haemorrhage)
  37. 37. Sinusoidal pattern
  38. 38. What are the features of a normal tracing?Baseline FHR 110-160 BPMBaseline Variability > 5 pbm (10-25)2 Accelerations > 15 BPM > 15 sec / 20 min traceNo decelrations
  39. 39. Normal -Reassuring CTG
  40. 40. Interpertation of CTGNormal -Reassuring(R)- CTG with all 4 FeaturesSuspicious (equivocal)- one non reassuring category and reminder are reassuringAbnormsal -Non reasurring (NR) - 2 or more non-reassuring categories or one or more abnormal categories.
  41. 41. Is Normal CTGs always Reassuring?With normal CTC the chance of fetus to develop hypoxia is 1.5% due to unpredictable acute eventsSo a normal CTG is always Reassuring
  42. 42. Is NR CTGs always worrisome ?60% CTG in Labour have 1 abnormal featureOnly 15-20% of NR CTGs are pathological.High false positive rate with unnecessary operative intervention for fetal distress.Thus NR CTG is not always worrisome.
  43. 43. ?? To reduce CS….
  44. 44. Consider these factors with abnormal CTG Clinical indication of doing CTG Abnormal patch of tracing from high risk case differ that from no risk case Maturity of the fetus Reduced variability and baseline tachycardia is conmen in preterm State of maternal pulseDrugs may cause maternal tachycardia– fetal tachycaedia Check blood pressure for hypotension in patients on Epidural
  45. 45. Consider these factors with abnormal CTG Posture of patient during CTGo Supine position give abnormal tracingo Some cord compression can get released by change posture and must be tried with variable deceleration Congenital fetal malformationColor Doppler of fetal heart to exclude congenital heart blockStage of labor and expected time of delivery Wether to deliver immediate or give sometime under close observation
  46. 46. Suspicious (Equivocal)CTGDo continuous monitoring for further development towards better or worse trace while instituting the corrective measures.Ideally check condition of fetus by FAS or FBS or scalp stimulation test.However ,if liquor is meconium stained ---Deliver immediately
  47. 47. Correct reversible causesChange mother position from supine to left lateral position-----increase uterine blood flowImprove maternal oxygenation—100% O2 by masKCorrect maternal hypotension –IV fluidDecrease or stop any oxytocin infusionRemove vaginal prostaglandins
  48. 48. Secondary tests of fetal well-beingVibro-acoustic stimulationUsed as a substitute for scalp sampling when CTG –is NRNormal ----------if FHR acceleration > 15 bpm for 15 seconds within 15 seconds after the stimulation with prolonged fetal movements.Abnormal ----Only 50% have acidotic PH
  49. 49. Fetal blood samplingIf the pH >7.25 --- observe.If the pH 7.2 and 7.25---repeatedwithin 30 minutes.If the pH <7.2----repeat immediatelyIf pH still low -- Prompt delivery
  50. 50. Scalp stimulation.Firm digital pressureGentile pinch by atramatic Allis forcepsFetal pulse oximetry.