Background <p>Neonates with congenital kidney failure or acute kidney injury often require continuous kidney replacement therapy (CKRT). Historically, venous access for CKRT in this population has relied on non-approved adult catheters, commonly via the internal jugular (IJ) vein. Limited international reports describe using the umbilical vein for CKRT, but this practice is not widespread in the USA. The Nuwellis® dual lumen extended length catheter (dELC), originally created for adult ultrafiltration, may support alternative access for neonatal CKRT.</p> Methods <p>This case series describes the clinical course of four neonates requiring CKRT using a 6 French Nuwellis® dELC placed in the umbilical vein at University of Iowa Stead Family Children’s Hospital and Children’s of Alabama. Patient demographics, CKRT prescriptions, access characteristics, and complications were reviewed.</p> Results <p>All four neonates underwent successful umbilical vein placement of the 6 Fr dELC. Weight at initiation ranged from 2.23 to 4.1&#xa0;kg, with blood flow rates 20–40&#xa0;mL/min. Epoprostenol anticoagulation was used in three patients. Half of the cohort later transitioned to a tunneled catheter, and one transitioned to an IJ catheter following fluid removal. One catheter developed hub cracks likely related to lumen caps, and one patient experienced flow limitations attributed to positioning rather than catheter function. Two patients had no catheter-related complications.</p> Conclusions <p>Umbilical venous access using the 6Fr dELC may represent a viable alternative for neonatal CKRT. Coil reinforcement within the catheter may support patency and better functionality. Additional studies are needed to assess safety and broader applicability.</p> Graphical abstract <p>A higher resolution version of the Graphical abstract is available as <InternalRef RefID="MOESM1">Supplementary information</InternalRef></p> <p></p>