Hwang JH, et al. - Researchers sought the risk factors for subclinical umbilical catheter-related thrombosis (UCRT) and examined its correlation with clinical morbidities. They monitored the presence of thrombosis in infants without any symptoms linked with umbilical catheterization using abdominal ultrasonography within 1 week after umbilical catheter removal. Occurrence of UCRT was noted in 26 (19.0%) of 137 infants. The multivariate analysis revealed correlation of high serum calcium concentration with subclinical UCRT. No significant correlation was observed between the subclinical UCRT and the neonatal morbidities in preterm infants. Based on these findings, they recommend considering hypercalcemia in the assessment of infants with subclinical UCRT, and routine checking of calcium levels in infants with umbilical catheters.