Tachysystole with Recurrent Late Decelerations in an Induced Nullipara
A 32-year-old nulliparous woman at 40 weeks and 5 days is admitted for induction of labour because of post-dates pregnancy. Her body mass index is 31 kg/m²; she has no other medical problems and a normal 20-week scan. The cervix is 2 cm dilated, 50% effaced, station −2 (Bishop score 4). A 10 mg dinoprostone vaginal insert is placed. Seven hours later the midwife calls you: contractions are every 2 minutes and last 70 seconds, the baseline fetal heart rate is 155 beats/min with minimal variability, and there are recurrent late decelerations to 90 beats/min lasting about 45 seconds. Maternal pulse is 104 beats/min, blood pressure 118/70 mmHg, temperature 37.2°C. On vaginal examination the cervix is 4 cm dilated, 70% effaced, station −2, and the membranes are intact. There is no history of uterine surgery.
1. What is your interpretation of the cardiotocograph, and what will you do in the next 15 minutes?
Read the worked answer
Interpretation. This is a category II tracing drifting towards III: tachysystole (about 30 contractions in 10 minutes), minimal variability and recurrent late decelerations. Late decelerations indicate impaired uteroplacental oxygen transfer with each contraction, not simply cord compression. The maternal tachycardia suggests pain, dehydration or evolving chorioamnionitis - check for fever and uterine tenderness.
Actions in the next 15 minutes
- Stop the oxytocin and remove the dinoprostone insert - it is removable, and reducing contraction frequency is the fastest intervention available.
- Left lateral position; intravenous crystalloid 500–1000 mL; check blood pressure.
- Acute tocolysis: terbutaline 250 µg subcutaneously (or 0.25 mg slow IV) unless contraindicated.
- Assess for abruption (tenderness, bleeding, hypertonus). There is no scar, so rupture is unlikely but still consider it.
- Vaginal examination to exclude cord prolapse; keep membranes intact for now.
- Continuous monitoring with a senior midwife at the bedside; document times, actions and responses.
If tachysystole resolves and the tracing becomes category I, oxytocin may be restarted cautiously after a period of stability. If late decelerations persist after three or four contractions without oxytocin, the tracing is effectively category III - expedite delivery by the quickest safe route. Oxygen is not a routine treatment and must not substitute for the steps above.
2. Four hours later she is fully dilated, station 0, the fetal head is direct occipitoposterior with marked caput, and she has been pushing for 90 minutes with recurrent late decelerations. Estimated fetal weight is 3.6 kg. How do you decide between a rotational operative delivery and caesarean section?
Read the worked answer
Frame the question. At full dilatation, with a station 0 direct occipitoposterior head, 90 minutes of pushing and recurrent late decelerations, the fetus needs to be delivered soon. The real choice is which route delivers it fastest with least trauma in your hands and this unit - not 'vaginal versus caesarean' in the abstract.
Prerequisites for any operative vaginal delivery: full dilatation; head engaged at or below station 0; position and attitude known; estimated weight not excessive; clinically adequate pelvis; empty bladder; effective analgesia; an experienced operator; consent; and immediate access to theatre and a neonatologist. If any is missing, caesarean is the correct answer.
Options here
- Manual rotation to occipito-anterior followed by direct traction forceps or vacuum - success around 80–90% in trained hands.
- Rotational forceps (Kielland) - effective but with higher maternal trauma; only for a trained operator.
- Vacuum in the OP position is possible but has higher failure and cephalohaematoma rates; avoid after a prolonged second stage with marked caput.
- Caesarean at full dilatation carries increased risk of uterine extension, haemorrhage and bladder injury, so it is not a 'safe default'.
Decision. With an experienced operator and a station 0 head, a trial of manual rotation and instrumental delivery in theatre, with a double set-up, is reasonable. If rotation fails, or three contractions of traction produce no descent, abandon and proceed to caesarean. Document the assessment, the plan and the reasoning.
3. She declines caesarean section and asks to keep pushing. How do you respond, and what must be documented?
Read the worked answer
Respect the refusal. A woman with capacity may refuse caesarean section even when the fetus is at risk; her autonomy is not overridden by concern for the fetus. Your task is to ensure the refusal is informed.
What to do
- Move to a calm, private setting; involve the most senior obstetrician available and the neonatologist.
- State the concern plainly: recurrent late decelerations mean the fetus may be short of oxygen, and delay increases the risk of hypoxic-ischaemic encephalopathy, stillbirth or neonatal death.
- Explain alternatives honestly, including continued pushing under continuous monitoring with immediate conversion if the tracing deteriorates, and the possibility of instrumental delivery.
- Explore her reasons - fear of surgery, a previous birth experience, family pressure - and address anything correctable.
- Offer a second opinion and an interpreter if needed. Do not coerce, threaten or withdraw care.
Documentation. Record that she has capacity, what she was told (including the risks of death and disability), what she understood in her own words, who was present, that alternatives were offered, and her decision. Continue full monitoring and escalate immediately if she changes her mind. If she later loses capacity, act in her best interests, with a second senior opinion recorded.