Investigation of umbilical venous vessels anatomy and diameters as a guideline for catheter placement in newborns.

Umbilical cord catheters (UCC) are important for the primary care of critically ill newborns. To analyze anatomical variations of the umbilical vein (UV) and its further course, we performed abdominal spiral-CT examinations on stillborns. The aim of the study was to explore the high incidence of mal-positioned UCCs and to improve their positioning. Eighteen stillborns were investigated (29.2 weeks ± 6.7 weeks (IQR)). CTs were performed using either air or contrast medium injection into the UV. We measured the diameter at the narrowest points of (i) the umbilical vein, (ii) the segmental portal vein, (iii) the left portal vein, (iv) the umbilical recess, and (v) the ductus venosus. The branching angles between (a) the umbilical vein and intrahepatic veins and (b) the ductus venosus and umbilical recess were measured. The diameter of the UV increases from 3.4 to 11 mm (median [IQR]:4.6 mm [4.2-6.9]: r  = 0.64). The left portal vein has a larger diameter (3.6 mm [2.6-4.55]; r  = 0.43) than the left segmental portal vein (2.3 mm [1.8-2.75]; r  = 0.23). The diameter of the ductus venosus (2.5 mm [1.6-3.4]; r  = 0.59) is half that of the umbilical recess (5.1 mm [3.3-6.2]; r  = 0.43). The most obtuse angle is formed by the junction between the umbilical recess and ductus venosus (151° [133-159]; r  = 0.001). The branch angle from the outgoing UV into the left portal vein is more obtuse (128° [123-144]; r  = 0.0001) than that of the segmental portal vein (115° [105-119]; r  = 0.0001). To avoid mal-positioning, our data suggest the use of a soft catheter. The UV and its extensions are wide enough to admit a 4 Fr. catheter without complete obstruction. Clin. Anat. 31:269-274, 2018. © 2017 Wiley Periodicals, Inc.