Newborn after umbilical arterial catheter placement AXR supine shows an umbilical arterial catheter that loops back upon itself in the aorta and whose tip projects in the right iliac artery at S3. The umbilical venous catheter tip projects at the junction of the inferior vena cava and the right atrium. The diagnosis was low malposition of the umbilical arterial catheter and appropriate position of the umbilical venous catheter.