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Diagnosed preterm labour with intact membranes — MRCEM SBA MCQ

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HardObstetric and gynaecological emergenciesDiagnosed preterm labour with intact membranesMRCEM SBA

A 29-year-old woman at 31+2 weeks’ gestation attends an emergency department with regular painful contractions. She is haemodynamically stable and afebrile, with no vaginal bleeding or fluid loss. Speculum examination shows a closed cervix and intact membranes. After one hour, contractions persist but there is no cervical dilatation. Specialist transvaginal ultrasonography measures the cervical length at 12 mm. Fetal assessment is reassuring. She has not received antenatal corticosteroids, has no contraindication to nifedipine, and delivery is not planned. Which management plan is most appropriate now?

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Correct answer: B — Admit for corticosteroids and nifedipine, reassessing the need for magnesium sulfate.

Her symptoms and cervical length of 12 mm meet the NICE criterion for **diagnosed preterm labour** at 30 weeks or more: a length of 15 mm or less warrants treatment despite the absence of progressive dilatation. At 31+2 weeks, with intact membranes and no nifedipine contraindication, she should be admitted under obstetric care and offered both nifedipine tocolysis and antenatal corticosteroids. Magnesium sulfate for fetal neuroprotection should be reconsidered if labour becomes established or birth is planned within 24 hours; neither criterion is met now. ([nice.org.uk](https://www.nice.org.uk/guidance/ng25/chapter/recommendations)) **A** is tempting because magnesium sulfate can be considered at this gestation, but diagnosed preterm labour alone does not meet its timing criterion. **C** substitutes atosiban, which NICE recommends when nifedipine is contraindicated; it is not contraindicated here. **D** delays indicated tocolysis until established labour, missing the opportunity to treat diagnosed labour. **E** similarly delays corticosteroids, although these are offered for diagnosed preterm labour from 24+0 to 33+6 weeks. A closed cervix does not negate the positive cervical-length assessment. ([nice.org.uk](https://www.nice.org.uk/guidance/ng25/chapter/recommendations))

Reference: NICE NG25: Preterm labour and birth, recommendation 1.7.4 (10 June 2022) — https://www.nice.org.uk/guidance/ng25/chapter/recommendations NICE NG25: Preterm labour and birth, recommendations 1.8.3–1.8.4 and 1.9.2 (10 June 2022) — https://www.nice.org.uk/guidance/ng25/chapter/recommendations NICE NG25: Preterm labour and birth, recommendation 1.10.3 and definition of established preterm labour (10 June 2022) — https://www.nice.org.uk/guidance/ng25/chapter/recommendations