Table 1.

Incidental findings during thyroid ultrasound (US) in children < 8 months old

Finding	N (%)a	First noted on US at weeks of life:modeb (range), weeks
Cyst or colloid cyst	16 (4.7%)	4 (4–24)
Ectopic thymus	14 (4.1%)	4 (4–16)
Hypoechoic nodule	7 (2.0%)	4 (4–8)
Absent left thyroid lobe	1 (0.3%)	4 (no range)
Congenital foregut cyst	1 (0.3%)	4 (no range)

^aNumber (N) is the number of infants with the given feature mentioned at any of the study visits. % is given with reference to the 342 infants who completed the 4-week study visit, which was the first visit during which thyroid was imaged.

^bMode represents the central tendency among visits at 4 weeks, 8 weeks, 16 weeks, 24 weeks, and 32 weeks