A Sterile Vaginal Examination (SVE) is a common clinical procedure performed late in pregnancy or during labor to assess the physical state of the cervix and the position of the baby. Healthcare providers use this digital examination to gather objective data on how labor is progressing toward birth. The term “sterile” emphasizes the use of sterile gloves and aseptic technique to minimize the risk of introducing bacteria into the reproductive tract.
The Clinical Reasons for a Vaginal Examination
The primary purpose of an SVE is to determine the progress of labor by checking the status of the cervix. It monitors labor’s movement from the latent phase into the active phase and through to complete dilation. The examination also helps assess a patient’s readiness for labor near term or determine the optimal approach for induction.
During active labor, the SVE allows providers to track the rate of cervical change and fetal descent. This information helps inform decisions about the need for interventions, such as artificially rupturing the membranes or determining when the patient can begin pushing. Examinations are also indicated when there are specific clinical concerns, such as evaluating the cause of bleeding or confirming the status after a premature rupture of membranes.
While the SVE is a standard tool, it is not mandatory or required until active labor is confirmed or specific concerns arise. Routine weekly checks before labor begins are sometimes offered, but they are not always medically necessary. The information gathered from the SVE is only a snapshot in time and does not perfectly predict the exact timing of birth.
Interpreting Dilation, Effacement, and Station
The SVE provides three measurements that describe the progression of labor, often given together in a sequence: dilation, effacement, and station. Understanding these terms helps a patient grasp the physical changes occurring in their body.
Dilation refers to the opening of the cervix, the muscular ring at the base of the uterus. This measurement is expressed in centimeters on a scale from 0 to 10. A closed cervix is 0 centimeters, and full dilation, which allows for the baby’s passage, is 10 centimeters.
Effacement describes the thinning and shortening of the cervix. Throughout most of pregnancy, the cervix is firm and measures several centimeters in length. As labor approaches, the cervix softens and thins out, measured as a percentage from 0% to 100%. A cervix that is 100% effaced is completely thinned out.
Station indicates how far the baby’s presenting part, usually the head, has descended into the pelvis. This measurement uses a scale relative to the ischial spines, bony points within the pelvis. When the baby’s head is level with these spines, it is referred to as 0 station, indicating the baby is engaged.
Negative numbers, such as -1 or -3, mean the baby’s head is still above the ischial spines. Conversely, positive numbers, like +1 or +3, mean the baby has moved below the spines and is descending further into the birth canal. A station of +5 generally means the baby is crowning, or visible at the vaginal opening.
Informed Consent and What to Expect
During the procedure, the patient is typically asked to lie on their back with their knees bent and legs apart. The provider will insert two gloved fingers into the vagina to manually feel the cervix and the baby’s position. The physical examination is very quick, usually lasting only a few moments, but some patients may find it uncomfortable or even painful.
The concept of informed consent means the patient has the right to fully understand the procedure and make a voluntary choice to accept or decline it. Before an SVE is performed, the healthcare provider must explain why it is being suggested, the risks and benefits, and any alternatives. A patient can decline an examination at any time, especially if it is being offered routinely before active labor is established.
One minor risk associated with frequent SVEs is a slightly increased chance of infection, particularly if the amniotic sac has already ruptured. Some patients may also experience light spotting or bleeding immediately following the examination. Patients should always feel empowered to ask questions or request a pause during the examination.