Intrapartum fetal survellence

DR. Mohit Satodia DR.BHARTI GOEL

GOAL The timely identification and rescue of the fetus at risk of neonatal and long term morbidity from intrapartum hypoxic insult

Intrapartum monitoring FHR monitoring Intermittent auscultation(IA) Electronic fetal monitoring(EFM) Fetal Scalp pH Fetal Pulse oximetry Fetal scalp lactate testing ST waveform analysis

FETAL HEART RATE MONITORING External FHR monitoring- Hand-held Doppler ultrasound probe External transducer

External FHR monitoring-

TECHNICAL CONSIDERATIONS Basis for FHR monitoring is beat to beat recording For practical purposes ,this is possible only when direct fetal electrocardiograms are recorded with a scalp electrode. Paper speed is important. Commonly used are 1,2 or 3 cm/min. 1 cm/min a) good records for clinical purposes and limiting the cost and amount of paper b)crowding together of the record making baseline variability difficult to interpret.

Contd 3 cm/min- a) useful when record is difficult to interpret at slow speed i.e. during second stage of labor b) waste of paper more

Internal FHR monitoring Spiral electrode attatched to the fetal scalp with a connection to FHR monitor. The fetal membranes must be ruptured, and the cervix must be at least partially dilated before the electrode may be placed on the fetal scalp.

Intermittent auscultation In uncomplicated pregnancies . Doppler better than stethoscope. Every 15 - 30 minutes in active phase of first stage and every 5 minutes in second stage Listen in the absence of active pushing and toward the end of the contraction and at least for 30seconds after each contraction ACOG JUlY 2009 CONTINUOUS EFM No benefit in low risk Continuous EFM -when risk factors for present Every 15 minutes in first stage and every 5 minutes during the second stage.

Fetal Assessment : IA & EFM Surveillence Low-Risk High-Risk Pregnancies Pregnancies Acceptable methods Intermittent Auscultation* Yes Yes (a) Continuous Electronic Fetal Monitoring (EFM) Yes Yes (b) First-stage Labour 30 min 15 min (a,b) Second stage labour 15 min 5 min (a,c) Evaluation Intervals a- before, during and especially after a contraction for 60 sec b- includes evaluation of tracing every 15 min c- evaluation of tracing every 5 min (ACOG & AAP 2007)

INDICATIONS FOR CONTINUOUS EFM Antepartum risk factors Abnormal Doppler umbilical artery velocimetry Suspected IUGR APH HTN / preeclampsia (current pregnancy) DM Multiple pregnancy Uterine scar / previous CS Iso-immunisation Oligohydramnios / polyhydramnios Maternal medical conditions(including severe anaemia, cardiac disease, hyperthyroidism, vascular disease, renal disease)

Risk factors during labour Prolonged rupture of membranes (> 24 hours) Meconium-stained or blood-stained liquor Fetal bradycardia Fetal tachycardia Maternal pyrexia > 38 C Chorioamnionitis Vaginal bleeding in labour Prolonged active first stage of labour (> 12 hours regular uterine contractions with cervical dilatation>3cm) Prolonged second stage of labour .

Other indications Any use of oxytocin whether for induction or for augmentation of labour Before and for at least 20 minutes after administration of prostaglandin Epidural analgesia (immediately after inserting an epidural block)

Benefits of EFM over IA Reduced risk of neonatal seizures(RR 0.50) No benefit over IA did not reduce perinatal mortality(RR, 0.85) did not reduce the risk of cerebral palsy (RR, 1.74) Risks of EFM High false-positive results. Increased rates of surgical intervention High interobserver and intraobserver variability COCHRANE 2006

Electronic fetal monitoring Various components include -Baseline -Variability -Accelerations -Decelerations

External fetal monitoring BASELINE The mean FHR rounded to increments of 5 bpm during a 10minute segment, excluding: Periodic or episodic changes Periods of marked FHR variability Segments of baseline that differ by more than 25 bpm The baseline must be for a minimum of 2 minutes in any 10-minute segment Normal : 110160 bpm Tachycardia: > 160 bpm Bradycardia: 25 bpm

Short term variability small changes in fetal beat to beat intervals under physiological conditions Long term variability- certain periodicity in the direction and size of these changes causes oscillations of fetal heart rate around mean level In FHR tracings short term variability is superimposed over long term variability as minimal deflexions, not interpreted by naked eye, therefore in clinical practice variability means long term variability

Long term variability characterized by frequency and amplitude Frequency is difficult to assess correctly Therefore , variability is usually quantitated by amplitude of the oscillations around baseline heart rate.

The tracing shows an amplitude range of ~ 10 BPM (moderate variability ).

Factors affecting variability Normal variability : 98% fetuses not acidotic Decreased variability: Fetal metabolic acidosis , CNS depressants, fetal sleep cycles, congenital anomalies, prematurity, fetal tachycardia, preexisting neurologic abnormality, betamethasone. Increased variability (saltatory pattern):Acute hypoxia or cord compression, eg 2nd Stage

ACCELERATION A visually apparent abrupt increase in the FHR 10 BPM above baseline for >10 sec >32 weeks: >15 BPM above baseline for > 15 sec Prolonged acceleration lasts >2 min but

Intrapartum fetal survellence

Health & Medicine

fetal scalp

risk factors

variability

risk

efm

labour

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