Supplementary Material for: Umbilical Venous Catheter Malposition Is Associated with Necrotizing Enterocolitis in Premature Infants

<i>Objective:</i> The etiology of necrotizing enterocolitis (NEC) remains elusive despite known associations with several factors, including intestinal ischemia related to the effects of umbilical arterial catheterization on the mesenteric circulation. However, the role of the mesenteric venous circulation has yet to be studied as a potential cause of NEC. We examined the association between umbilical venous catheter (UVC) position and the development of NEC in premature infants. <i>Design:</i> A prospective cohort study was performed to examine the effect of UVC on portosystemic shunting via the ductus venosus (DV) and its potential role in NEC. <i>Results:</i> We recruited 132 premature infants, 62 of which had a birth weight ≤1,500 g. NEC was noted in 12 (19%) patients. All infants weighing ≤1,500 g underwent an attempt at UVC insertion. The UVC status was classified as appropriate (<i>n</i> = 39), unsuccessful (<i>n</i> = 9), or malpositioned (<i>n</i> = 14). Among the NEC patients, 7 (58%) had a UVC malposition and 3 (25%) had an unsuccessful attempt. These rates were significantly higher than in patients without NEC (14 and 12%, respectively). Multivariable logistic regression analysis confirmed birth weight (OR 2.2, 95% CI 1.2-4.7, <i>p</i> = 0.001) and UVC malpositioning (OR 6.9, 95% CI 1.6-35.4, <i>p</i> = 0.007) as independent risk factors associated with NEC. <i>Conclusions:</i> Unrecognized withdrawal of a UVC into the portal vein or DV is associated with an increased incidence of NEC in infants weighing ≤1,500 g. The data support the need for additional studies to examine this effect. Confirmation of a causal relationship will raise the need to reassess UVC insertion criteria and strategies for more closely monitoring the catheter tip position.