The process of labor involves significant physical changes, primarily the condition of the cervix. Cervical dilation is the opening of the cervix, the lower part of the uterus connecting to the vagina, which must expand for the baby to pass through. Effacement is the corresponding process where the cervix shortens, softens, and thins out. Measuring dilation and effacement is the primary method healthcare providers use to determine the body’s readiness for labor and track its progression toward delivery.
Understanding the Dilation Check Procedure
A cervical check is the standard way to measure dilation and effacement. The procedure involves a healthcare provider inserting one or two gloved, lubricated fingers into the vagina to physically feel the cervix. The provider estimates the width of the opening to determine dilation, which is measured in centimeters (cm) on a scale from 0 cm (closed) to 10 cm (fully dilated).
The provider also assesses effacement, measured as a percentage from 0% (thick) to 100% (paper-thin). Full dilation of 10 cm and 100% effacement are required before the pushing stage of delivery can begin. While the procedure is quick, the results are an estimate based on the provider’s experience, and measurements can sometimes vary slightly between clinicians.
Checks During Routine Late-Term Appointments
Cervical checks often begin during routine prenatal appointments in the later stages of pregnancy, typically starting around 36 or 37 weeks. The purpose of these initial checks is to establish a baseline and see if the cervix has begun “ripening,” the natural changes that occur before labor. These exams may also be performed during the 35 to 37-week period to collect a swab for Group B Streptococcus (GBS) screening.
Finding a cervix already dilated a few centimeters in late pregnancy does not reliably predict when labor will start. Some individuals may be dilated for weeks, while others remain closed until labor begins suddenly. Because these checks are not predictive of timing and carry a small risk of discomfort or infection, they are often considered optional and may be declined by the patient.
Monitoring Progression Once Labor Begins
The frequency of cervical checks increases once a person is admitted to the hospital or birth center in labor. The first check occurs during the triage process upon arrival to determine if the patient is in active labor and should be admitted. Active labor is defined as the point when the cervix is dilated to 6 centimeters or more.
Once admitted, checks monitor the progress of dilation, ensuring labor advances at a reasonable rate. The standard protocol for checks during active labor is typically every two to four hours. This rhythm guides medical decisions, such as when to administer pain medication like an epidural or increase the dosage of labor-inducing medication like oxytocin.
If the patient feels a strong urge to push, a check is performed immediately to confirm full dilation before beginning the second stage of labor. A lack of cervical change over several hours may indicate stalled labor, prompting a discussion about interventions or, in some cases, a cesarean delivery.
Medical Reasons to Limit or Increase Checks
The standard schedule for cervical checks may be altered based on specific clinical circumstances. A major reason to limit checks is when the amniotic sac, or “water,” has broken. Once the protective barrier of the membranes is gone, each check increases the risk of introducing bacteria into the uterus, which can lead to chorioamnionitis.
Checks may be performed more frequently if there is suspicion of rapid labor progression or if the fetal heart rate suggests distress. A check is also required before a healthcare provider performs a membrane sweep. Patients have the right to decline any cervical check, provided there is no immediate medical threat to the health of the parent or baby.