Nonreassuring Fetal Status

Nonreassuring fetal status is a clinical term for signs that the fetus may be hypoxic or acidotic, such as an abnormal heart rate tracing, thick meconium with abnormal tracing, abnormal fetal blood gas or absent movements. Causes include cord compression, uterine hyperstimulation, abruption, maternal hypotension, placental insufficiency and uterine rupture. It matters because delay in action causes brain injury and stillbirth, and many cases need delivery within minutes.

• Common in labour, especially with induction or augmentation.
• Risk factors: induced labour, oxytocin use, growth restriction, post term pregnancy, previous caesarean section, maternal fever.
• Many false alarms occur, and fetal blood sampling reduces unnecessary operations.

Features include an abnormal fetal heart pattern on auscultation or cardiotocography, meconium stained liquor, reduced fetal movements or absent fetal heart. Mothers may have bleeding, pain or fever.

• Heart rate below 110 or above 160 beats per minute, or decelerations after contractions.
• Thick meconium or blood in the liquor.
• Differential diagnosis: normal fetal sleep, maternal fever, drug effect, cord compression, abruption, uterine rupture, fetal anaemia, fetal arrhythmia, technical fault.
• Complications: hypoxic ischaemic encephalopathy, cerebral palsy, meconium aspiration, stillbirth, neonatal death, emergency caesarean section.

The approach is to confirm the abnormality, find the cause and decide on delivery.

• Heart rate by Pinard or hand-held Doppler every 15 minutes in the first stage and every 5 minutes in the second stage; continuous cardiotocography when available.
• Pathological cardiotocography features: baseline above 180 or below 100 beats per minute, variability below 5 beats per minute for more than 90 minutes, late decelerations for more than 30 minutes, prolonged deceleration beyond 3 minutes, sinusoidal pattern.
• Vaginal examination for cord, cervix, descent and bleeding; maternal pulse, blood pressure, temperature, uterine tone.
• Fetal scalp blood lactate where available (below 4.2 mmol/L normal, 4.2 to 4.8 borderline, above 4.8 abnormal) or pH (below 7.20 abnormal).

The principle is intrauterine resuscitation, correction of the cause and delivery when the tracing does not recover.

• Supportive: call for senior help; lateral position (left or right); stop oxytocin; two cannulae; check maternal blood pressure and treat hypotension; oxygen 10 L/minute by mask may be given while preparing for delivery; empty the bladder.
• Pharmacological: Ringer's lactate 500 to 1000 mL IV over 15 to 30 minutes; terbutaline 0.25 mg subcutaneous once for uterine hyperstimulation; ephedrine 5 to 10 mg IV for hypotension after epidural; ampicillin 2 g IV 6-hourly plus gentamicin 5 mg/kg IV once daily for maternal fever above 38 degrees Celsius; paracetamol 1 g oral 6-hourly (maximum 4 g in 24 hours) for fever; tranexamic acid 1 g IV over 10 minutes for bleeding; oxytocin 10 IU IM at birth.
• Procedures: amnioinfusion with sodium chloride 0.9 percent 500 mL intrauterine over 30 minutes then 3 mL per minute for variable decelerations with oligohydramnios; assisted vaginal delivery by vacuum or forceps if fully dilated with the head engaged; emergency caesarean section aiming for birth within 30 minutes of the decision for persisting abnormality, and within 15 minutes for bradycardia or cord prolapse; newborn resuscitation with bag and mask.
• Special groups: women with previous caesarean section and suspected uterine rupture go to theatre at once; thick meconium with a depressed baby needs airway clearance and ventilation.
• Red flags: bradycardia beyond 3 minutes, absent variability, late decelerations, cord prolapse, abruption, uterine rupture, maternal collapse.
• Follow-up: umbilical cord blood gas at birth; newborn Apgar score and examination; monitor for neonatal encephalopathy over 72 hours; review at 6 weeks postpartum.