Differentiating Between Threatened Preterm Labor and Preterm Labor

Diagnostic Criteria

The American College of Obstetricians and Gynecologists recommends that cervical length measurement by transvaginal ultrasound is the most reliable diagnostic tool for differentiating between threatened preterm labor and preterm labor 1

The American College of Obstetricians and Gynecologists suggests that initial assessment should include documentation of frequency and duration of contractions, assessment for risk factors for preterm birth, and checking for signs of infection, placental abruption, and fetal well-being 1
The American Journal of Obstetrics and Gynecology recommends performing digital cervical examination to assess dilation and effacement, noting that digital examination may be difficult in women with skeletal dysplasia or anatomical variations 3

The Centers for Disease Control and Prevention recommends that if cervical changes present (dilation ≥2 cm or length ≤2 cm), diagnose as true preterm labor, and administer corticosteroids between 24-34 weeks 2, 4
The American College of Obstetricians and Gynecologists suggests that for women with threatened preterm labor who have unknown GBS status, obtain vaginal-rectal swab for culture, and initiate GBS prophylaxis if the patient has a positive GBS screen within the preceding 5 weeks 2

The American Journal of Obstetrics and Gynecology recommends that for women with skeletal dysplasia, cervical examination may be difficult, and standard management of preterm labor may need modification 3
The Centers for Disease Control and Prevention suggests that discontinue antibiotics given for GBS prophylaxis if the patient is determined not to be in true labor 2