Preterm labour can complicate about 10% of
pregnancies.
It refers to regular contractions with changes
in the cervix prior to 37+0 weeks of gestation.
Preterm labour can result in a very premature
baby – but if recognized early, interventions
can be done to lower the risk to the baby.
Here are some important things that you need
know about diagnosing preterm labour:
When I take a history in a woman with suspected
preterm labour, here are some important questions
I ask:
Is there a prior history of spontaneous preterm
labour?
At what gestational age?
This is the most important risk factor for
preterm labour.
What is the current gestational age and how
was this determined?
Accurate dating is important to determine
management and prognosis for the fetus.
When did the contractions start and how painful
are they?
Is there any vaginal bleeding?
Significant pain may be an indication of placental
abruption or uterine rupture.
Significant bleeding can be concerning for
placental abruption, placenta previa or vasa
previa.
Is there any fluid leakage?
A common cause of preterm labour is preterm
rupture of membranes.
Consider the colour of the fluid – amniotic
fluid is clear while green fluid is suggestive
of meconium and fetal distress.
Is there fetal movement?
This is important in assessing fetal well
being.
When examining the patient, here are some
important things to remember:
Start with a sterile speculum exam.
Lubricate the speculum with saline to visualize
the cervix and swab the posterior fornix for
the fetal fibronectin test.
Fetal fibronectin test has a good negative
predictive value for preterm labour.
Transvaginal ultrasound is helpful to assess
cervical length.
A cervical length > 30mm has a high negative
predictive value for delivery prior to 34
weeks of gestation.
A cervical length <15mm at <28 weeks has a
high positive predictive value for preterm
labour.
Bedside ultrasound to assess estimated fetal
weight (EFW), position, placental location
Non-stress test (NST) should be performed
to assess fetal well being.
