Fetal Distress

Fetal distress (increasingly termed "suspected fetal compromise" in contemporary guidelines, reflecting the imprecision of the older term) refers to evidence, most commonly from cardiotocography, of inadequate fetal oxygenation during labor, requiring prompt evaluation and, where confirmed and significant, expedited delivery.

Underlying causes include cord compression, placental insufficiency, uterine hyperstimulation (excessive contraction frequency reducing intervillous blood flow), maternal hypotension, and any of the acute causes covered in dedicated entries (abruption, uterine rupture, cord prolapse).

Abnormal fetal heart rate pattern on CTG, reduced fetal movements reported by the mother, and meconium-stained liquor (a non-specific but relevant additional marker, particularly thick, undiluted meconium).

• Cardiotocography interpretation is systematic, assessing baseline rate (normal 110 to 160 bpm), variability (normal 5 to 25 bpm), the presence and type of decelerations (early decelerations, mirroring contractions, are generally benign and reflect head compression; variable decelerations reflect cord compression and are concerning if atypical, deep, or prolonged; late decelerations, with the nadir occurring after the peak of the contraction, indicate uteroplacental insufficiency and are the most concerning pattern), and the presence of accelerations (reassuring)
• Traces are classified as normal, suspicious, or pathological (terminology and specific criteria vary slightly by guideline, e.g. NICE), guiding the urgency of the response
• Fetal blood sampling (scalp pH and/or lactate) may be used where available to further evaluate a pathological trace before committing to immediate delivery, where clinical circumstances allow time for this: a pH above 7.25 (or lactate below 4.2 mmol/L) is reassuring, 7.21 to 7.24 (lactate 4.2 to 4.8) is borderline and repeated, below 7.20 (lactate above 4.8) indicates significant acidosis requiring expedited delivery
• Fetal scalp stimulation, an acceleration in response to digital stimulation of the fetal scalp is reassuring and can avoid the need for fetal blood sampling in some cases

• Conservative measures first, where the situation allows: maternal repositioning (left lateral, to relieve aortocaval compression), correction of maternal hypotension (IV fluid bolus, particularly relevant after epidural top-up), stopping oxytocin infusion if uterine hyperstimulation is contributing, and, where hyperstimulation is significant, tocolysis with terbutaline 250 mcg SC to acutely reduce contraction frequency
• Maternal oxygen administration has not been shown to improve fetal outcomes and is not routinely recommended
• Persistent pathological trace not responding to conservative measures, or a clearly ominous pattern (prolonged bradycardia, or acidosis confirmed on fetal blood sampling), warrants expedited delivery: instrumental vaginal delivery if fully dilated and criteria are met, or emergency cesarean section (category 1 if immediately life-threatening, category 2 if urgent but not immediately life-threatening)
• Continuous reassessment and clear communication with the woman and her birth partner throughout, given the anxiety this situation understandably generates
• Neonatal team present at delivery for any significant fetal distress, with cord blood gas sampling at delivery to objectively assess the degree of any acidosis at birth

Referral: obstetric-led care throughout labor; immediate senior obstetric involvement for any pathological CTG trace not resolving with initial conservative measures.