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CTG Interpretation .pptx
- 1. CTG INTERPRETATION Wafaa Benjamin Basta ConsultantOb/ Gyn MatariaTeaching Hospital MRCOG –ERC Member Egyptian Board of Ob/Gyn Meeting - March 2019
- 2. Foetal Physiology • Fetus designed to cope with labour •Every fetus will have his/hers own unique physiological reserve all modified by his /hers antenatal and intra-partum risk factors. • Fetal physiology in labour will make all efforts to protect the myocardium
- 3. Control of Baseline Fetal Heart Rate andVariability • Pacemaker in SA node , Conduction bundle , AV node • CNS • Brain stem centre • Chemoreceptor and baroreceptor • Sympathetic and parasympathetic systems • Baseline heart rate – sum result of these factors • Baseline variability – integration of sympathetic and parasympathetic input • Gestation
- 4. Control of Baseline Fetal Heart Rate andVariability • CNS activity - increase activity leads to increased variability of heart rate • Chemoreceptors – hypoxia / hypercapnia → bradycardia • Baroreceptors - ↑ arterial pressure → bradycardia • Sympathetic system – adrenal medulla → epinephrine and nor-epinephrine • Parasympathetic system – vagal effect on SA node and AV node → decreased FHR
- 5. The well oxygenated fetus demonstrates a stable baseline and variability
- 8. Chemical (Chemo-receptors) • Responsive to ↑ in H+ CO2 ↓ Po2 • Stimulate parasympathetic nervous system to decrease FH • Gradual fall from baseline and delayed recovery.Take longer to recovery to baseline Mechanical Baro-receptors • Compression of umbilical artery • Increase in fetal systemic BP • Stimulates Baro-receptor to send impulse to cardiac inhibitory centre • FH slows Sharp drop • Usually 30 -60 seconds • Recovery to baseline • Not of concern if Baseline andVariability are reassuring.
- 9. A Normal Antenatal CTG
- 10. Features of a CTG • Baseline Rate bpm • Baseline variability bpm • Accelerations • Decelerations • Response to stimuli • Contractions • Fetal movements • Other
- 11. Features of a CTG • Baseline Rate bpm • Baseline variability bpm • Accelerations • Decelerations • Response to stimuli • Contractions • Fetal movements • Other Classified into : • Reassuring • Non-reassuring • Abnormal
- 13. RCOG Classification of CTGs • Normal CTG = all Three features are reassuring • Suspicious CTG = One non reassuring feature and two reassuring • Pathological CTG = One abnormal or Two non reassuring features
- 14. Features of CTG Fetal Heart rate feature classification Baseline (bpm) Variability (bpm) Decelerations Accelerations Reassuring 110 - 160 ≥5 None Present Absence of accelerations with otherwise normal CTG is of uncertain significance Non-reassuring 100 – 109 110 - 160 <5 for ≥40 but <90 min • early •Variable •Single prolonged for up to 3 minutes Abnormal <100 >180 Sinusoidal pattern for ≥10 minutes <5 for >90 minututes • atypical • Late • Single prolonged for >3 minutes
- 15. Baseline Fetal Heart Rate {FHR} Mean level of FHR when this is stable, excluding Accelerations and Decelerations -Tachycardia -Bradycardia • Reassuring : 110 to 160 bpm at term • Non-reassuring : 100-109 bpm / 161-180 bpm • Abnormal: less than 100/ more than 180 bpm • Tachycardia with reduced STV = early hypoxia
- 17. BaselineTachycardia • Hypoxia • Chorio- amnionitis • Sepsis • Maternal fever • Maternal Anxiety • Maternal thyrotoxicosis • B-Mimetic drugs • Fetal anaemia • Heart failure • Arrhythmias • Prematurity
- 18. Baseline Bradycardia • Postdates • Drugs • Idiopathic • Arrhythmia's • Hypothermia. • Cord compression • Acute Hypoxia • Congenital heart
- 19. Baseline variability • The minor fluctuations on baseline FHR at 3-5 cycles bpm produces Baseline variability. • Examine imin segment and estimate highest peak and lowest trough. • Reassuring: 5-25 bpm – this indicates Normal-CNS. • Non-reassuring: > 5 bpm for 30-50 minutes • < 25 bpm for 15-25minutes • Abnormal: > 5 bpm for <50 minutes • <25 bpm for <25 minutes
- 20. BaselineVariability Para-Sympathetic affects short term variability whilst LongTerm is more Symp. CNS ,Drugs reduce Variability High gestation increases variability Mild Hypoxia may cause both S and para S stimulation
- 21. ReducedVariability • Hypoxia • Drugs • Extreme prematurity • Sleep • CNS abnormality.
- 23. Variability less than 5 bpm for 30-50 minutes
- 24. Accelerations • Must be >15 bpm and >15 sec above baseline • Should be >2 per 15 min period • Always reassuring when present • May not occur when fetus is “sleeping” • Should occur in response to fetal movements or fetal stimulation • Non reactive periods usually do not exceed 45 min • (>90 min and no accelerations is worrying)
- 25. Acceleration
- 26. Decelerations Transient slowing of FHR below the baseline level of more than 15 bpm and lasting for 15 sec. Or more.
- 27. Deceleration Reassuring: • Non • Early deceleration • Variable dec ,no concerning characteristic > 90 minutes Non-reassuring • Variable dec ,no concerning characteristic < 90 minutes • Variable dec ,with any concerning characteristic : • <50% of contractions for more than 30 minutes or more • >50% contractions for less than 30 minutes • Late deceleration in >50% contractions for less than 30 minutes {no maternal or fetal risk factors}
- 28. Deceleration Abnormal: • Variable dec ,with any concerning characteristic >50% contractions for more than 30 minutes {or less if fetal or maternal risk factors} • Late deceleration for more than 30 minutes {or less if maternal or fetal risk factors} • Bradycardia or a single deceleration over 3 minutes
- 29. Early Deceleration mirrors the contraction. = Head Compression Typically occurs as the head enters the pelvis and is compressed, i.e. it is a vagal response
- 30. Late Deceleration Follows every contraction and exhibits a slow return to baseline. = Fetal Hypoxia Is the response of a hypoxic myocardium
- 31. Variable Deceleration Show no relationship to contractions. = Cord Compression If frequent lead to hypoxia Without concerning features With concerning features
- 32. Non-reassuring – variable decelerations Concerning features • Biphasic or W shaped • Lasting >60 seconds • Failure to return to baseline • No shouldering • Reduced variability within the deceleration Variable decels with concerning features: • <50% of contractions for more than 30 minutes • >50% contractions for less than 30 minutes
- 34. Lasting > 60 seconds
- 35. Reduced variability within the deceleration
- 36. Failure to return to the baseline
- 37. No shouldering
- 38. Decelerations that become “Longer, later and deeper” are a worrying sign
- 39. Sinusoidal
- 42. Normal CTG • Variable decelerations with no concerning features are very common • They can be normal if there are no other non-reassuring features • They become non-reassuring if they persist for more than 90 minutes
- 44. Pathologic CTG
- 45. TAKE ACTION Suspicious Pathological • Inform Senior MW and doctor • Exclude acute events • Cord prolapse • Uterine rupture • Abruption • Think about MOTHERS • Start conservative measures • Investigate
- 46. Pathological CTG • If CTG remains pathological: Perform scalp stimulation If this leads to an acceleration, regard this as a sign the baby is healthy Only continue with FBS if the CTG remains pathological If there is no acceleration, consider FBS Or Expediting birth
- 47. Conservative measures • Left lateral / mobilise • Consider iv fluids • Reduce contractions: o Reduce/stop synto o Terbutaline • Paracetamol if temp/pulse raised
- 48. Remember….
- 50. Bradycardia 3 6 9 3 minutes Call obs reg, anaesthetist, theatre team Start Conservative measures Ask for terbutaline 6 minutes Prepare woman for theatre / instrumental Continue conservative measures 9 minutes Transfer to theatre and expedite birth ■ 95% of babies will recover before 9 minutes in the absence of cord prolapse, abruption, uterine rupture ■ If cord prolapse, abruption or rupture – expedite birth immediately
- 52. Decompensation of the CNS
- 53. Thank you Any questions ?!
Editor's Notes
- Imagine a coach arrives and takes this group of midwives to the (Airspace ) trampoline park here in Wolverhampton and we HAVE to complete a days training. Once we enter the trampoline park we have to complete the compulsory moves, theres a whole series of jumps, tilts, twists, tucks, swivel hips, seat drops, full arm swings, half twists with backward rotation, full twists with forward rotation, etc etc. you have to make your way through all the trampolines to get to the exit. You cant exit until all the compulsory sets are completed. How would we do ?? Some will do it and come out of the exit smiling and waving, others may not look like that at the exit…some may need a helping hand and some of us ……may not make it !! Some of us may have breathing, cardiac, muscular, neurological problems…… we all have an individual physiological reserve……so does the fetus. Fetal ability: already used to relatively hypoxic environment arterial O2 sats of around 70%..can be as low as 30% in labour Fetal haemoglobin is higher tha adult 18-22g/dl. Greater affinity for oxygen Fetal circulation designed to supply major organs readily with oxygenated blood. Think of yourselves on a trampoline or another time when you are physically exerting yourselves… and the heart muscle is working harder and harder …what do you do ) … what happens to your breathing.? You breathe faster and deeper…more o2 to the heart muscle…you make slow down… less workload on the myocardium…
- Similar to the adult…. the central nervous system is made of autonomic and somatic nervous systems. This is not just a photo showing stupidity of some men … it helps to represent the constant state of push & pull of the sympathetic and parasympathetic nervous systems . The constant state of interaction between the sympathetic NS increasing the FH and the parasympathetic NS decreasing it. The baseline is the agreement reached between the 2 systems. … look at the tie between the 2 men. They may have been moving backward and forward all day (lol) but the constant push pull results in the line forming between them….baseline. Agreement between the 2 systems. Constant fluctuation is the variability. A stable baseline and variability are the strongest indicator s that is a well oxygenated fetus.
- NICE 2017 Guidance CTG interpretation lets look at stickers Coloured RAG Flag Main change to normal, non reassuring and pathological The terminology regarding variables decelerations… now described as variables with without concerning characteristics Think about the bigger picture Scalp stimulation
- Remember the physiology… baroreceptor response to compression, mechanical causes, quick to fall, quick to recover, return to baseline. If there is atable baseline 110-160, normal variability and no risk factors then unlikely to be acidotic . Continue care …90 minutes!! s
- Remember the physiology… baroreceptor response to compression, mechanical causes, quick to fall, quick to recover, return to baseline. If there is atable baseline 110-160, normal variability and no risk factors then unlikely to be acidotic . Continue care …90 minutes!! s
- Remember the physiology… baroreceptor response to compression, mechanical causes, quick to fall, quick to recover, return to baseline. If there is atable baseline 110-160, normal variability and no risk factors then unlikely to be acidotic . Continue care …90 minutes!! s
- Remember the physiology… baroreceptor response to compression, mechanical causes, quick to fall, quick to recover, return to baseline. If there is atable baseline 110-160, normal variability and no risk factors then unlikely to be acidotic . Continue care …90 minutes!! s