A viability scan is an early ultrasound examination performed during pregnancy. This procedure offers early insights into the progress of the pregnancy, providing reassurance and important information. It uses sound waves to create images, allowing healthcare providers to assess the initial stages of gestation and confirm the pregnancy is developing as expected within the uterus.
Purpose and Timing of a Viability Scan
A viability scan serves several important purposes in early pregnancy. One primary reason for this scan is to confirm the pregnancy is located within the uterus, which helps to exclude ectopic pregnancy. Detecting an embryo’s heartbeat is another central aim, as this is a significant indicator that the pregnancy is progressing.
Viability scans are also used to determine the gestational age, providing an accurate estimated due date. This dating is typically more precise when based on ultrasound measurements than on the last menstrual period. The scan can also identify multiple pregnancies, allowing for appropriate care planning. Healthcare providers also use this scan to identify any visible early abnormalities or assess for complications like internal bleeding or hematomas.
Viability scans are typically performed in the first trimester, usually between 6 and 10 weeks of gestation. The optimal time is often considered to be around 7 to 9 weeks, as the embryo and heartbeat may be too small to be clearly visible earlier. If a scan is performed very early and findings are inconclusive, a follow-up scan is usually recommended later for more definitive results. This early assessment is helpful for individuals with a history of miscarriage, ectopic pregnancy, or those who have undergone fertility treatments.
The Viability Scan Procedure
Undergoing a viability scan is a straightforward process, typically involving minimal discomfort. Patients generally lie on an examination table, and the procedure usually takes around 15 to 30 minutes. There are two primary methods: transabdominal and transvaginal.
A transabdominal scan involves applying a gel to the abdomen, over which a transducer is gently moved. This transducer emits sound waves that create real-time images of the uterus and developing pregnancy on a monitor. For this method, a full bladder is often recommended, as it can help provide clearer images of the uterine structures.
In some cases, particularly in very early pregnancy or when clearer images are needed, a transvaginal scan may be performed. This method involves inserting a thin ultrasound probe, covered with a sterile sheath, into the vagina. This allows for a closer and more detailed view of the embryo and uterus. For a transvaginal scan, an empty bladder is usually preferred. Both methods are considered safe for the pregnant individual and the developing embryo, and the sonographer will explain the process.
Interpreting Viability Scan Results
Interpreting the results of a viability scan centers on assessing the early signs of a healthy, progressing pregnancy. “Viability” in this context refers to the pregnancy’s ability to continue developing. A positive viability scan confirms the presence of a gestational sac within the uterus. Within this sac, a yolk sac typically appears, followed by a fetal pole.
The most reassuring finding is the detection of a fetal heartbeat, which indicates a lower chance of miscarriage once observed. The size of the fetal pole, measured as crown-rump length (CRL), helps confirm gestational age. The presence of a heartbeat when the CRL is at least 7 millimeters is generally a strong indicator of a viable pregnancy. A normal viability ultrasound confirms a gestational sac and embryo with a visible heartbeat.
Sometimes, a viability scan might yield uncertain findings. A gestational sac might be visible without a clear yolk sac or fetal pole, or a fetal pole might be seen without a detectable heartbeat. If the gestational sac measures 25 millimeters or more without an embryo, or if a fetal pole measuring 7 millimeters or more lacks a heartbeat, these findings raise concerns about viability. In such situations, healthcare providers typically recommend a follow-up scan, scheduled 7 to 14 days later, to re-evaluate the pregnancy’s development and provide a more definitive diagnosis.