Obstetric Topics 39-40. Detection of fetal jeopardy during pregnancy and labor

I. Definition and Risk Assessment

Definition

• Fetal jeopardy/distress: fetus receives inadequate O2 and nutrients → hypoxia → acidosis → injury or death.
• CTG/NST are screening tests; interpret with gestational age, maternal disease, contractions, fever, bleeding and labor progress.

High-Risk Conditions

• HT/preeclampsia, GDM/diabetes, IUGR/FGR, postterm pregnancy, decreased fetal movements, oligo-/polyhydramnios, multiple gestation and previous stillbirth.

II. Antenatal Detection

Fetal Movement

• Kick count: reduced movement or <10 movements in 12 h → suspect compromise.
• Alternative practical method: mother lies on left side; if <10 movements in 1 h, repeat 1 h → persistent reduction needs NST + US.

Ultrasound and Doppler

• US: fetal growth, estimated fetal weight, abdominal circumference and amniotic fluid volume.
• AFI: oligohydramnios usually <5 cm; polyhydramnios usually >23-24 cm.
• Doppler: umbilical artery, middle cerebral artery and uterine artery.
• Umbilical artery abnormality → placental resistance/insufficiency.
• Absent or reversed end-diastolic flow → severe fetal danger.
• MCA redistribution/brain-sparing → fetal adaptation to hypoxia.
• Suspected IUGR/FGR: compare serial US to distinguish wrong dating, SGA and true growth restriction.

NST / Antenatal CTG

• NST: fetal heart rate recording without contractions; fetal movements should cause accelerations.
• Reactive NST: baseline 110-160/min + normal variability + ≥2 accelerations in 20 min.
• Acceleration after 32 weeks: ≥15 bpm for ≥15 sec.
• Before 32 weeks: 10 bpm for 10 sec may be accepted.
• Nonreactive NST → repeat another 20 min, use vibroacoustic stimulation, assess AFI/Doppler or perform BPP/contraction stress test.

Biophysical Profile and Contraction Stress Test

• BPP: NST + fetal breathing + fetal movements + fetal tone + AFI; each 0 or 2 → total 10.
• BPP 8-10: reassuring; 4-7: equivocal, depends on gestational age; 0-2 or <3: abnormal → urgent management/delivery.
• Contraction stress test (CST): oxytocin or nipple stimulation induces contractions → recurrent late decelerations = positive test → uteroplacental insufficiency.

III. CTG During Labor

Monitoring Methods

• Intermittent auscultation: Pinard/Doppler from one contraction to the next; suitable for low-risk labor if tracing remains reassuring.
• Continuous CTG/EFM: two-channel recording of FHR + uterine contractions.
• External CTG: abdominal Doppler + tocodynamometer.
• Internal CTG: fetal scalp electrode ± intrauterine pressure catheter; needs ruptured membranes and cervical dilation.

Normal CTG / Reactive Pattern

• Baseline FHR: 110-160/min.
• Variability: 5-25/min or moderate variability 6-25 bpm.
• Accelerations: reassuring, usually ≥15 bpm for ≥15 sec.
• Decelerations: none, or only early/isolated benign decelerations.

Abnormal CTG Findings

• Bradycardia: FHR <110/min → hypoxia, acidosis, cord prolapse, abruption, uterine rupture or maternal hypotension.
• Tachycardia: FHR >160/min → maternal fever/infection, dehydration, hyperthyroidism, drugs, fetal anemia or hypoxia.
• Reduced/absent variability: fetal sleep, prematurity, maternal sedation, fetal hypoxia/acidosis or CNS depression.
• Sinusoidal pattern: smooth wave-like tracing with absent variability → severe fetal anemia/hypoxia.

Decelerations

• Early deceleration / DIP I: mirrors contraction → head compression/vagal reflex → usually benign.
• Late deceleration / DIP II: begins after contraction starts, nadir after contraction peak → uteroplacental insufficiency → fetal danger sign.
• Variable deceleration / DIP III: abrupt variable timing/shape → cord compression.
• More dangerous if recurrent, deep, >60 sec, slow recovery or with reduced variability.
• Prolonged deceleration: FHR fall ≥2 min and <10 min; persistent bradycardia needs urgent action.

Categories

• Category I: normal baseline, moderate variability, no recurrent late/variable decelerations → observe.
• Category II: indeterminate/non-reassuring → correct reversible causes and reassess continuously.
• Category III: absent variability + recurrent late/variable decelerations or bradycardia; or sinusoidal pattern → abnormal acid-base status likely.

IV. Management

Antenatal Jeopardy

• Confirm abnormal result with repeated/complementary testing; assess gestational age, viability and maternal-fetal condition.
• Term with persistent compromise → deliver by induction or C-section according to obstetric conditions.
• Preterm stable fetus → close surveillance + correct reversible maternal causes; give corticosteroids if preterm delivery is likely.
• Severe preterm compromise → balance fetal maturity against risk of intrauterine hypoxia/death.

Non-Reassuring CTG During Labor

• Call senior obstetric/neonatal help; check maternal pulse to avoid confusing maternal and fetal HR.
• Search for cause: tachysystole/oxytocin, maternal hypotension, fever/infection, hypoxia, cord prolapse, abruption or uterine rupture.
• In-utero resuscitation: lateral repositioning, stop/reduce oxytocin, IV fluids, treat hypotension/fever/hypoxemia.
• Consider tocolysis (e.g. terbutaline) for tachysystole and rule out cord prolapse.
• Fetal scalp stimulation or scalp pH/lactate may help if available; pH <7.20-7.21 supports fetal asphyxia/acidosis.
• Persistent category III/pathological CTG, persistent decelerations or fetal pH <7.2 → immediate delivery.
• Assisted vaginal delivery if cervix fully dilated and head low; otherwise emergency C-section.
• Common severe-compromise target: delivery within about 30 min, guided by clinical urgency and feasibility.