Ultrasound Recommendations at 13 Weeks Gestation

Primary Components of 13-Week Ultrasound

A transabdominal ultrasound should be performed to assess fetal viability, number of fetuses, biometry, and nuchal translucency measurement, as recommended by the American College of Radiology 1, 2
Nuchal translucency measurement is essential at this gestational age as it serves as a screening tool for chromosomal abnormalities, according to the American College of Radiology 1, 2

Some practices perform a detailed first trimester obstetric ultrasound between 12 weeks 0 days and 13 weeks 6 days, as suggested by the American College of Radiology 1, 2
First trimester detection of structural abnormalities is possible in approximately 27.3% of cases with anomalies, as reported by the American College of Radiology 2
Common anomalies detectable at 13 weeks include defects of the cranial vault, midline brain, and abdominal wall, according to the American College of Radiology 2

For multiple gestations, the 13-week scan should include assessment of chorionicity, amnionicity, and intertwin membrane, as recommended by the American College of Radiology 1, 2
In multiple gestations, discrepant crown-rump length (CRL) measurements may be an early marker for twin-to-twin transfusion syndrome, according to the American College of Radiology 2
Fetal echocardiography can be performed between 12 weeks 0 days and 13 weeks 6 days in high-risk cases, such as previous child with congenital anomaly, maternal diabetes, IVF pregnancy, or multiple gestations, as suggested by the American College of Radiology 1, 2

Doppler studies (middle cerebral artery, umbilical artery) are not recommended at 13 weeks as they have no established role at this gestational age, according to the American College of Radiology 1, 3
Biophysical profile has no role in the first trimester and should not be performed, as recommended by the American College of Radiology 1, 2