[Rate and risk factors of tip displacement of umbilical venous catheterization at different indwelling time points in preterm infants].

<b>Objectives:</b> To investigate the rate and risk factors of tip displacement of umbilical venous catheterization (UVC) in preterm infants. <b>Methods:</b> This was a multicenter cohort study. Study population were preterm infants admitted to 44 tertiary hospitals in China between October 2019 and August 2021. Demographic information, general clinical data, UVC indwelling conditions and related complications were collected. The primary outcome was the rate of UVC tip displacement. The observation time points were 2 d and 7 d after UVC. They were grouped according to UVC displacement, gestational age, and birth weight. Binary Logistic regression was used to analyze the risk factors of UVC tip displacement. <b>Results:</b> The 2 086 preterm infants had a gestational age of (29.9±2.3) weeks and a birth weight of (1 248±298) g. There were 1 106 male preterm infants (53.0%). The rate of UVC displacement at 2 d and 7 d were 34.6% (721/2 086) and 33.6% (494/1 470), respectively, with no statistically significant difference (<i>χ</i>²=0.35, <i>P</i>=0.533). Univariate analysis indicated that male infants, small gestational age, low birth weight and small catheter diameter were all risk factors for UVC tip displacement at the 2 d time point (all <i>P</i><0.05). Multivariate analysis showed that small catheter diameter was an independent risk factor for tip displacement at both 2 d (<i>OR=</i>0.47, 95%<i>CI</i> 0.34-0.66) and 7 d (<i>OR=</i>0.39, 95%<i>CI</i> 0.25-0.59) time points (both <i>P</i><0.001). <b>Conclusions:</b> The rate of UVC tip displacement is high in preterm infants. It should be avoided to deliberately select a small diameter catheter for UVC, and pay attention to the imaging monitoring of the tip position after UVC.