Preterm Contractions Without Cervical Change

Preterm contractions without cervical change are uterine tightenings before 37 weeks that do not produce cervical dilatation or effacement over 2 hours or on repeated assessment, and the cervical length stays 30 mm or more. They are the commonest reason for attendance with suspected preterm labour. Causes include dehydration, urinary infection, constipation, uterine irritability, intercourse and normal Braxton Hicks activity. The point is to avoid unnecessary drugs and admission while still picking up the minority who progress.

• Risk factors: dehydration, urinary or genital infection, multiple pregnancy, polyhydramnios, uterine fibroid, physical exertion.
• Most deliver at term.
• Steroids and tocolysis are not given.

Women have irregular tightening, often painless, that settles with rest or fluids, with no bleeding, leaking fluid or pelvic pressure. The cervix is closed or less than 3 cm and unchanged over 2 hours.

• Contractions irregular and not increasing in strength.
• Fetal movements normal.
• Differential diagnosis: threatened preterm labour, urinary tract infection, abruption, chorioamnionitis, appendicitis, constipation, round ligament pain.
• Complications: unnecessary admission and drugs, anxiety, missed progression to true labour, adverse effects of tocolysis if given wrongly.

The approach is to document absence of cervical change and look for a treatable cause.

• Cardiotocography with tocography for 1 to 2 hours; repeat cervical assessment after 2 hours.
• Transvaginal ultrasound: cervical length 30 mm or more, or negative fetal fibronectin (below 50 ng/mL) in the intermediate group.
• Urine dipstick and culture, high vaginal swab, full blood count, C-reactive protein if fever.
• Blood pressure and urine protein; ultrasound for liquor and presentation.

The principle is hydration, treatment of the cause, reassurance and discharge with clear warning signs.

• Supportive: oral fluids 1 to 2 litres over 2 hours; rest in the left lateral position; empty the bladder; reassurance; discharge when contractions settle; teach to return for regular contractions, bleeding, leaking fluid, reduced fetal movements or fever; avoid intercourse for 1 week.
• Pharmacological: cefalexin 500 mg oral 6-hourly for 7 days for urinary infection or bacteriuria; metronidazole 400 mg oral 12-hourly for 7 days for bacterial vaginosis; lactulose 15 mL oral 12-hourly for constipation; paracetamol 1 g oral 6-hourly as needed (maximum 4 g in 24 hours); no steroids, no magnesium sulphate and no tocolysis.
• Procedures: none.
• Special groups: women with a previous preterm birth, a twin pregnancy or a cervical length of 25 mm or less need repeat assessment within 1 week and vaginal progesterone 200 mg at night from diagnosis to 36 weeks.
• Red flags: regular contractions every 5 minutes or less, cervix 3 cm or more dilated, bleeding, membrane rupture, fever, reduced fetal movements.
• Follow-up: antenatal review within 1 week; cervical length scan in 1 to 2 weeks if risk factors exist; routine antenatal care with attention to symptoms.