Vaginal Exam for Preterm Labor

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Exam Overview

If you have symptoms of preterm labor, your doctor or nurse-midwife may examine you by feeling your cervix . If your contractions continue over a period of hours, you may be examined periodically to see whether your cervix is opening (dilating) or thinning (effacing).

These exams allow your health professional to:

  • Find out how much your cervix has opened and thinned.
  • Find out how far the baby has moved down the birth canal (station).
  • Check for fluid leaking from your vagina using a sterile speculum . If fluid is present, it will be tested to determine whether it is amniotic fluid , which is a sign that your amniotic sac has ruptured.

Why It Is Done

Vaginal exams are done when a pregnant woman has:

  • Uterine contractions that may have changed her cervix and may be preterm labor. The cervix may open and thin without strong or painful contractions.
  • Unusual pelvic pressure or back pain.
  • Vaginal bleeding.


Preterm labor is diagnosed when a woman who is 20 to 37 weeks pregnant has uterine contractions and her cervix has changed, as seen with a vaginal exam.

Preterm labor is not diagnosed if contractions are occurring but the cervix is not becoming thinner or more dilated (open).

What To Think About

When a vaginal exam is not done to assess for preterm labor

When the amniotic membranes rupture early ( preterm premature rupture of membranes, or pPROM ), sterile speculum exams are kept to a minimum, and digital exams are avoided. This is meant to reduce the risk of infecting the uterus and fetus.

When the placenta is known to be overlapping or covering the cervix ( placenta previa ), vaginal exams are completely avoided. Disturbing the placenta can trigger bleeding.

Complete the medical test information form (PDF) (What is a PDF document?) to help you prepare for this test.


ByHealthwise Staff

Primary Medical Reviewer Sarah Marshall, MD - Family Medicine

Specialist Medical Reviewer William Gilbert, MD - Maternal and Fetal Medicine

Current as ofMay 22, 2015