Adrenal gland length in euploid and trisomy 18 fetuses at 11-13 weeks.

OBJECTIVES To establish a normal range for fetal adrenal gland length at 11-13 weeks' gestation and to investigate whether the length is altered in fetal trisomy 18. METHODS Fetal adrenal gland length was measured by three-dimensional ultrasound in fetuses at low risk of aneuploidies (n = 400) and another group at high risk, including 380 euploid fetuses and 41 with trisomy 18. The data of the low-risk group were used to establish a reference range of adrenal gland length with crown-rump length (CRL). In the high-risk group, adrenal gland length in the euploid and trisomy 18 groups was compared. RESULTS In the low-risk group, fetal adrenal gland size increased exponentially with fetal CRL from a median of 2.3 mm at CRL of 45 mm to about 4.4 cm at CRL of 84 mm. In trisomy 18, the median adrenal gland length for CRL was significantly lower than the median in the low-risk group (-1.37 mm; interquartile range: - 1.67 to - 0.99 mm, p < 0.0001). In euploid fetuses, the adrenal gland size was not significantly from the low-risk group (p = 0.100). CONCLUSION Trisomy 18 is associated with adrenal gland hypoplasia which is apparent at 11-13 weeks' gestation.