Contractions before 37 weeks
Obstetrics
Triage, 22 to 36+6 weeks
The first question
Is this preterm labour, and if it might be, what can be done in the next 48 hours?
Two patients: the gestational age and the maternal stability first, then the fetal status.
- 01
Assess
Contraction frequency, cervical length or examination, fetal fibronectin, membranes, fetal status, infection.
- 02
Decide the likelihood
A long closed cervix with a negative fibronectin: unlikely to deliver soon. Cervical change: treat as preterm labour.
- 03
Treat
Steroids, magnesium for neuroprotection before 32 to 34 weeks, tocolysis to complete steroids and transfer, GBS prophylaxis, neonatal team aware.
Where it is
Each opens the structure on the 3D pelvis.
History that discriminates
- Contraction frequency, duration, pain
- Fluid, bleeding, discharge
- Urinary symptoms, fever
- Prior preterm birth, cervical surgery, short cervix, multiple pregnancy
- Substance use, trauma
Examination that discriminates
- Temperature and pulse
- Uterine activity and tenderness
- Fetal heart rate, presentation
- Speculum first if membranes may be ruptured; cervical assessment
Investigations
- Transvaginal cervical length
- Fetal fibronectin (before any examination or intercourse in 24 hours)
- Urinalysis and culture, GBS swab
- Ultrasound for presentation, growth, liquor
- Monitoring
What the image changes
The differential
| Diagnosis | Favours | Against | Urgency |
|---|---|---|---|
| Preterm labour | Regular contractions with cervical change, short cervix, positive fibronectin | Long closed cervix, negative fibronectin | emergent |
| Threatened preterm labour, no change | Contractions that settle, cervix unchanged | Cervical change | urgent |
| Urinary infection or pyelonephritis | Dysuria, pyuria, flank pain, fever | Normal urine | urgent |
| Abruption | Constant pain, bleeding, hard uterus | Intermittent painless tightenings | emergent |
| Chorioamnionitis | Fever, tachycardia, tenderness, ruptured membranes | Afebrile, intact membranes | emergent |
| Braxton Hicks | Irregular, painless, no cervical change | Regularity and cervical change | routine |
Pitfalls this pathway refuses
- Waiting to see if it is real before giving steroids at 28 weeks
- Tocolysis with abruption or infection
- Sending fibronectin after a digital examination