To determine the optimal timing of cranial ultrasound scans (USs) for identifying preterm neonates weighing less than 1500 g at birth who develop intracranial complications of prematurity.
Observational study at an urban county hospital.
Serial USs from neonates with less than 1500-g birth weight (BW) admitted to the neonatal intensive care unit between January 1995 and December 1996 were reviewed by a pediatric neuroradiologist in a blinded random manner.
Two hundred forty-eight neonates (78%) underwent at least 3 USs, 32 (10%) had 2 USs and 37 (12%) only 1 US. The initial US was normal in 156 neonates (49%) and abnormal in 161 (57%). The principal abnormalities included intraventricular hemorrhage (IVH) (n = 74), periventricular echogenicity (PVE) (n = 68), ventriculomegaly (n = 7), and solitary cysts (n = 9). Severe IVH (n = 17) occurred in 13 (11.4%) of 114 neonates at less than 1000-g BW and 4 (5%) of 79 neonates of BW 1000 to 1250 g. In 11 cases (65%), the severe IVH was clinically unsuspected. For neonates weighing less than 1000 g, IVH was diagnosed by days 3 to 5 in 10 (77%) of 13, by days 10 to 14 in 11 (84%) of 13, and by day 28 in all neonates; for neonates 1001 to 1250 g, IVH was diagnosed in 1 (24%) of 4 by days 3 to 5, 2 (50%) of 4 by days 10 to 14, and 3 (75%) of 4 by day 28. One infant's condition was diagnosed on routine US before discharge from the hospital. Cystic periventricular leukomalacia (PVL) was noted in 9 neonates; in 4 of the 9 cases, increased PVE was present on the initial US and cyst formation was obvious by the second US. For 4 neonates (3 with BW <1000 g), all routine USs were negative and cystic PVL was noted on the predischarge US in these cases. Nonobstructive ventriculomegaly in the absence of IVH or cystic PVL was observed in 14 neonates. In 6, it was noted on the initial screening US; in 4 of the cases, it evolved after the third screening US. Two hundred fifty-six neonates had a US before discharge from the hospital; 181 (72%) were normal and 75 (28%) abnormal. Nine significant lesions were identified by the US before discharge from the hospital (ie, severe IVH [n = 1], cystic PVL [n = 4], and ventriculomegaly [n = 4]).
The following screening protocol is recommended: (1) Neonates of less than 1000-g BW: initial US on days 3 to 5 (should identify at least 75% of cases of IVH and some PVE abnormalities); second US on days 10 to 14 (should detect at least 84% of IVH and identify early hydrocephalus and early cyst formation); third scan on day 28 (should detect all cases of IVH, as well as assess PVE and ventricular size); and final scan before discharge from the hospital (should detect approximately 20% of significant late-onset lesions). (2) Neonates of 1000- to 1250-g BW: initial US at days 3 to 5 (should detect at least 40% of significant abnormalities); a second scan at day 28 (should detect at least 70% of significant abnormalities); and a predischarge scan (should detect all late-onset significant lesions). (3) Neonates of 1251- to 1500-g BW: an initial scan at days 3 to 5; and a second scan before discharge from the hospital if the clinical course is complicated.