J Korean Soc Med Ultrasound.  2001 Mar;20(1):65-69.

Prenatal Sonographic Measurement of the Fetal Thyroid Gland

• Ahn YC
• Kim YH
• Cho WS
• Bae WK
• Kim IY

Abstract

PURPOSE
To investigate whether the fetal thyroid gland could be examined by prenatal ultrasonography and to establish the normal range of fetal thyroid width according to the gestational age.
MATERIALS and METHODS
The width of the fetal thyroid was determined by prenatal ultrasonography from 118 pregnant women. Three of the mothers had current or previous thyroid disease and the widths of the fetal thyroid were determined from 115 normal subjects. The width of the fetal thyroid was defined by a maximum transverse distance of the thyroid gland between two carotid arteries on transverse scan of the fetal neck. We analysed the causes of non-measurable cases. The width of the fetal thyroid and Neo-TSH were compared in 19 subjects, including 3 subjects with current or previous thyroid disease.
RESULTS
We could measure the fetal thyroid widths in 95 cases(80%). The fetal thyroid widths of mothers without current or previous thyroid disease was 0.9 -2.36cm, which showed linear correlation with gestational age (Y=0.0506X + 0.0439, r2=0.5661). Causes of non-measurable cases were neck flexion(65%), prone posi-tion(22%), and overlapped fetal neck by arm or shoulder(13%). Of the 19 neonates with Neo-TSH level, one case had a mother with a thyroid disease and showed increased width of the fetal and high Neo-TSH.
CONCLUSION
The fetal thyroid was measured in 80% of prenatal ultrasonography and the width of the fetal thyroid showed linear correlation with gestational age. We assumed that the width of the fetal thyroid could be useful for diagnosing fetal thyroid disorder when maternal thyroid disease exists.

MeSH Terms

Arm
Carotid Arteries
Female
Gestational Age
Humans
Infant, Newborn
Mothers
Neck
Pregnant Women
Reference Values
Thyroid Diseases
Thyroid Gland*
Ultrasonography*
Ultrasonography, Prenatal