A short cervix during pregnancy refers to the condition where the lower part of the uterus, known as the cervix, measures shorter than a typical length. This measurement can indicate an increased likelihood of preterm birth. Identifying this condition early allows healthcare providers to consider specific interventions to support a healthy pregnancy.
Understanding Cervical Length
The cervix is a muscular canal connecting the uterus to the vagina. During pregnancy, it normally remains long, firm, and closed to help keep the developing baby securely within the womb. A “short cervix” is generally defined as a cervical length less than 25 millimeters (2.5 centimeters) before 24 weeks of pregnancy. A measurement below this threshold indicates a higher risk.
Medical Detection Methods
Determining if a person has a short cervix primarily relies on medical imaging techniques, as this condition often presents without noticeable symptoms. Self-diagnosis of a short cervix is not possible, making professional medical evaluation important. The most accurate and reliable method for measuring cervical length is a transvaginal ultrasound (TVS). During a transvaginal ultrasound, a small ultrasound transducer is gently inserted into the vagina, providing a clear and direct view of the cervix. This approach allows for precise measurement from the internal opening of the cervix (internal os) to the external opening (external os). Unlike transabdominal ultrasounds, a TVS is not affected by factors like maternal obesity or fetal position, which can sometimes obscure the cervix or lead to less accurate measurements.
Cervical length screening is typically performed during the second trimester of pregnancy, often between 16 and 24 weeks, as part of a routine anatomy scan. For individuals with a history of preterm birth or other risk factors, cervical length checks might begin even earlier. If an initial transabdominal ultrasound suggests a short cervix, a transvaginal ultrasound is usually recommended to confirm the measurement and obtain a more accurate assessment. Healthcare providers take multiple measurements, using the shortest one for assessment, and may apply gentle pressure to observe for any changes in cervical length, such as funneling.
Implications for Pregnancy
A short cervix during pregnancy is a significant concern because it increases the likelihood of preterm labor and preterm birth. The earlier it happens, the greater the potential health risks for the newborn. These risks can include the need for extensive medical care and, in some cases, long-term health challenges.
The mechanism behind this increased risk is that a shorter cervix may be less able to withstand the growing pressure of the pregnancy. This can lead to the cervix opening or dilating too soon, often without contractions or other signs of labor. This condition is sometimes referred to as cervical insufficiency. While a short cervix indicates an elevated risk, it is important to remember that many individuals with a short cervix still carry their pregnancies to full term.
Management Approaches
Once a short cervix is identified, healthcare providers can implement various management strategies to help extend the pregnancy and reduce the risk of preterm birth. The specific approach depends on individual circumstances, including the exact cervical length measurement and previous pregnancy history.
One common intervention involves progesterone supplementation, typically administered as a vaginal gel, suppository, or capsule daily. This hormone can help reduce the risk of preterm birth in individuals with a short cervix, particularly those with a single pregnancy and no prior history of preterm birth. Progesterone is usually started before 24 weeks of gestation and continued until around 36 weeks.
Another intervention is a cervical cerclage, which involves placing a stitch or suture around the cervix to reinforce it and help keep it closed. This surgical procedure is often considered for individuals with a history of preterm birth or significant cervical shortening, especially if the cervix measures less than 10-15 millimeters. The cerclage is typically placed between 12 and 24 weeks of pregnancy and is removed closer to the due date. Increased monitoring with follow-up ultrasound scans may also be recommended to track cervical length progression.