INTRAPARTUM FETAL ASSESSMENT 1.pptx

Intrapartum fetal monitoring

1. INTRAPARTUM FETAL ASSESSMENT SOUNDHARYA 21/11/23

2. LEARNING OBJECTIVES Electronic fetal monitoring - Internal (direct) electronic monitoring - External (indirect) electronic monitoring Fetal heart rate patterns Continuous CTG monitoring Other intrapartum assessment techniques Intrapartum surveillance of uterine activity

3. INTERNAL ELECTRONIC MONITORING Bipolar electrode attached directly to fetal scalp Reference electrode on maternal thigh to eliminate electrical interference Electrical fetal cardiac signal – P wave, QRS complex, T wave - amplified and fed into cardiotachometer for heart rate calculation Peak R- wave voltage is the part of fetal electrocardiogram most reliably detected

4. Premature atrial contraction – heart rate acceleration Continuous R-R wave fetal heart rate computation  beat-to-beat variability The American Academy of Pediatrics and the American College of Obstetricians and Gynecologists (2012) Relative contraindications to internal fetal monitoring: certain maternal infections(human immunodeficiency virus (HIV), herpes simplex virus, and hepatitis B and C virus)

5. EXTERNAL(INDIRECT) ELECTRONIC MONITORING Fetal heart rate is detected through maternal abdominal wall by ultrasound doppler principle Shift in frequency of waves  reflected from moving fetal heart valves and pulsatile blood ejected during systole Transducer – emits ultrasound Sensor – detects shift in frequency of reflected sound Doppler signals edited electronically  fetal heart rate data printed onto monitor paper

6. FETAL HEART RATE PATTERNS National institute of child health and human development(NICHD) has proposed definitions for interpretation of fetal heart rate patterns during labor : Baseline fetal heart rate activity - Rate - Beat to beat variability - Fetal arrhythmias - Distinct pattern - Sinusoidal or saltatory fetal heart rates Accelerations Decelerations

7. BASELINE FETAL HEART RATE ACTIVITY Approximate mean FHR rounded to increments of 5 bpm during a 10 minute segment excluding - periodic or episodic changes - segments of baseline that differ by more than25 bpm The baseline must be for a minimum of 2 min in any 10 min segment or the baseline for that time period is indeterminate.

8. RATE The baseline fetal heart rate decreased an average of 24 bpm between 16 weeks and term, or approximately 1 beat/min per week  maturation of parasympathetic (vagal) heart control Normal FHR baseline: 110–160 bpm
Tachycardia: FHR baselines > 160 bpm
Bradycardia: FHR baseline < 110 bpm Wandering Baseline: Baseline rate is unsteady and “wanders” between 120 and 160 bpm Suggestive of neurologically abnormal fetus , may occur as a preterminal event.

9. BRADYCARDIA(<110 bpm) Congenital heart block Severe fetal compromise Maternal Hypothermia

10. TACHYCARDIA(>160 bpm) Fetal compromise Maternal hypotension(epidural analgesia) Maternal administration of parasympathetic (atropine) or sympathomimetic(terbutaline) Cardiac arrhythmias

11. BASELINE VARIABILITY Fluctuations in the baseline FHR that are irregular in amplitude and frequency Variability is visually quantified as the amplitude of peak-to-trough in bpm Baseline fluctuations of two cycles per minute or greater —Absent: amplitude range undetectable —Minimal: amplitude range detectable but ≤ 5 bpm or fewer —Moderate (normal): amplitude range 6–25 bpm —Marked: amplitude range > 25 bpm

12. 1.Undetectable, absent variability. 2. Minimal variability, ≤ 5 bpm. 3. Moderate (normal) variability, 6 to 25 bpm. 4. Marked variability, > 25 bpm. 5. Sinusoidal pattern.

13. INCREASED VARIABILITY Fetal breathing Fetal body movements DECREASED VARIABILITY Analgesic drugs during labor Maternal hypoxemia Magnesium sulfate CNS depressants- Narcotics, barbiturates, phenothiazines, tranquilizers,general anesthetics .

14. Persistently flat fetal heart rate baseline(absent variability)within the normal baseline rate range and without decelerations  previous insult to the fetus resulting in neurological damage Reduced baseline heart rate variability is the single most reliable sign of fetal compromise

15. SINUSOIDAL PATTERN Visually apparent, smooth, sine wave-line undulating pattern in FHR baseline with a cycle frequency of 3–5 per minute which persists for 20 min or more Excluded from definition of fetal heart rate Variability May be observed in - Fetal intracranial hemorrhage -Severe fetal asphyxia -Severe fetal anemia from Rh alloimmunization, fetomaternal hemorrhage,twin -twin transfusion syndrome or vasa previa with bleeding

16. PERIODIC FETAL HEART RATE CHANGES Deviations from baseline that are temporarily related to uterine contractions - Accelerations - Decelerations

17. ACCELERATIONS A visually apparent abrupt increase (onset to peak in < 30 sec) in the FHR At ≥32 weeks, acceleration has a peak of ≥15 bpm above baseline, with a duration of ≥15 sec but < 2 min from onset to return Before 32 weeks, an acceleration has a peak of ≥10 bpm above baseline, with a duration of ≥ 10 sec but < 2 min from onset to return Prolonged acceleration lasts ≥ 2 min, but < 10 min If acceleration lasts 10 min, it is a baseline change Common in labor and are nearly always associated with fetal movement.

18. DECELERATIONS EARLY DECELERATION Symmetrical gradual decrease and return of the FHR associated with uterine contraction usually during active labor Head compression  vagal nerve activation as a result of dural stimulation  mediates the heart rate deceleration Decrease in FHR is calculated from the onset to the nadir of the deceleration
Onset, nadir and recovery of the deceleration coincident with the beginning, peak and ending of the contraction respectively

19. LATE DECELERATION Symmetrical gradual decrease and return of the FHR associated with uterine contraction Onset, nadir and recovery of the deceleration occur after the beginning, peak and ending of the contraction

20. VARIABLE DECELERATION Abrupt decline in the heart rate and onset that commonly varies with successive contractions. The decelerations measure ≥ 15 bpm for ≥ 15 seconds and have an onset-to-nadir phase of < 30 seconds. Total duration is < 2 min

21. PROLONGED DECELERATION: Isolated deceleration greater than 15 bpm lasting 2 minutes or longer but < 10 minutes from onset to return to baseline Commonly seen in Hyperactivity Cord entanglement or cord prolapse Maternal hypotension. Placental abruption Maternal seizures including eclampsia and epilepsy,

22. Guidelines for Methods of Intrapartum Fetal Heart Rate Monitoring Acog.org/clinical/clinical-guidance/practice-bulletin/articles/2009/07/intrapartum-fetal-heart-rate-monitoring-nomenclature-interpretation-and-general-management-principles

23. CONTINUOUS CTG MONITORING ANTEPARTUM Offer continuous CTG monitoring for women in labour with any of the following antenatal maternal risk factors Previous caesarean birth or other full thickness uterine scar Any hypertensive disorder needing medication prolonged ruptured membranes Any vaginal blood loss other than a show Suspected chorioamnionitis or maternal sepsis Pre-existing diabetes (type 1 or type 2) and gestational diabetes requiring medication. Any of the antenatal fetal risk factors Nonncephalic presentation Fetal growth restriction Small for geatational age Advanced gestational age Polyhudramnios or oligohydramnios Reduced fetal movements in 24 hrs before onset of regular contractions www.nice.org.uk/guidance/ng229fetalmonitoringinlabour

24. INTRAPARTUM CONTINUOUS CTG MONITORING Contractions that last >2 min or 5 or more contractions in 10 minutes Presence of meconium Maternal pyrexia Suspected chorioamnionitis or sepsis Fresh vaginal bleeding that develops in labour Suspected antepartum hemorhage Maternal pulse >120 bpm on 2 occasions 30 minutes apart Severe hypertension >160/110 mmHg Reading of 2+ of protein on urinalysis and a single reading of BP>140/90 Oxytocin Regional analgesia Offer continuous CTG monitoring for women who have or develop any of the following new intrapartum risk factor www.nice.org. uk/guidance/ng229fetal monitoringinlabour

25. OTHER INTRAPARTUM ASSESSMENT TECHNIQUES FETAL SCALP BLOOD SAMPLING Procedure : illuminated endoscope is inserted through the dilated cervix against the fetal scalp. Blood is collected through an incision of 2mm.pH of the blood is measured If the pH is > 7.25,labor progress is monitored If between 7.20 and 7.25, the pH measurement is repeated within 30 minutes. If the pH is < 7.20 indicates fetal acidosis, scalp blood sample is collected immediately and urgent delivery

26. FETAL SCALP STIMULATION Pinching of the scalp with an Allis clamp or gentle digital stroking just before obtaining blood is done Presence of FHR acceleration indicates normal scalp blood pH

27. VIBROACOUSTIC STIMULATION Vibroacoustic stimulation is done using electronic larnyx placed on maternal abdomen Response is considered normal if a fetal heart rate acceleration of at least 15 bpm for at least 15 seconds occurs within 15 seconds after the stimulation

28. FETAL ELECTROCARDIOGRAPHY As fetal hypoxia worsens, there are changes in the T-wave and in the ST segment of the fetal ECG. Mature fetus exposed to hypoxemia  elevated ST segment with a progressive rise in T-wave height that can be expressed as a T:QRS ratio INTRAPARTUM DOPPLER VELOCIMETRY Abnormal Doppler waveforms may signify pathological umbilical-placental vessel resistance

29. THREE TIER FETAL HEART RATE INTERPRETATION NATIONAL INSTITUTES OF HEALTH WORKSHOPS THREE TIER CLASSIFICATION SYSTEM Category I—Normal Includes all of the following: Baseline rate: 110–160 bpm Baseline FHR variability: moderate Late or variable decelerations: absent Early decelerations: present or absent Accelerations: present or absent

30. CATEGORY II - INDETERMINATE Include all FHR tracings not categorized as Category I or III. Baseline rate - Bradycardia not accompanied by absent baseline variability - Tachycardia Baseline FHR variability - Minimal baseline variability - Absent baseline variability not accompanied by recurrent decelerations - Marked baseline variability Accelerations - Absence of induced accelerations after fetal stimulation
- Periodic or episodic decelerations
- Recurrent variable decelerations accompanied by
- minimal or moderate baseline variability
- Prolonged deceleration ≥ 2 min but < 10 min
- Recurrent late decelerations with moderate baseline variability
- Variable decelerations

31. CATEGORY III – ABNORMAL Include either: -Absent baseline FHR variability and any of the following Recurrent late decelerations
Recurrent variable decelerations Bradycardia Sinusoidal pattern

32. Resuscitative measures for category II and III tracings(ACOG 2013) Acog.org/clinical/clinical-guidance/practice-bulletin/articles/2009/07/intrapartum-fetal-heart-rate-monitoring-nomenclature-interpretation-and-general-management-principles

33. INTRAPARTUM SURVEILLANCE OF UTERINE ACTIVITY INTERNAL UTERINE PRESSURE MONITORING Amniotic fluid pressure is measured between and during contractions by a fluid-filled plastic catheter with its distal tip located above the presenting part EXTERNAL MONITORING Uterine contractions measured by transducer placed against abdominal wall Transducer button moves in proportion to the strength of the contraction  converted into a measurable electrical signal that indicates the relative intensity of the contraction

34. Normal uterine activity is defined as five or fewer contractions in 10 minutes over a 30-minute window. Tachysystole was defined as more than five contractions in 10 minutes

35. THANK YOU