Anastomosis of the umbilical arteries: physiologic variant or complication of umbilical catheterization?

Sir, A premature baby presented with respiratory distress syndrome (RDS), signs of shock, and disseminated intravascular coagulation (DIC). After intubation, a 3.5-F catheter was placed in the right umbilical artery prior to transport to our hospital. Upon admission, placement of an umbilical venous catheter was attempted to facilitate the baby©s further management. By mistake, this catheter (size 3.5 F as well) was inserted into the left umbilical artery because the umbilical blood vessels were repeatedly manipulated during the initial attempt at placing a catheter. After being inserted approximately 2.5 cm it merged with the first catheter in the right umbilical artery and with the tip at the same position, between L3 and L4 (Figs.1, 2). Erroneous insertion of a catheter into the wrong umbilical artery is a common complication of umbilical blood vessel catheterization. A false track of the catheter through the first arterial vessel wall, the jelly of Wharton, and the second arterial vessel wall is possible, although unlikely for the following reasons. The umbilical arteries are maximally contracted after birth to prevent blood loss. External manipulation of the arteries and sufficient oxygenation contribute to further vasoconstriction. Since the tip of the catheter is blunt, it is unlikely to penetrate an arterial vessel wall from outside. With one catheter inserted there would not be enough space for a second in a constricted blood vessel. Perforation of an umbilical artery near the peritoneum usually leads to hemorrhage into the connective tissue sheath or diffuse suffusion of the abdominal wall with blood, which our patient did not experience. Gross accumulation of intraabdominal blood with shock after umbilical arterial rupture can occur [1]. With a perforation of the umbilical vein even the umbilical venous blood pressure can be high enough to extravasate considerable amounts of blood into the abdominal cavity [2]. In some situations a perforation of the umbilical vessel wall is sealed as long as the catheter remains in place [3]. Perforation into the right umbilical artery would be expected to occur perpendicularly and probably incompletely, predisposing to perivascular dissection, dissection into the subintimal space, or invagination of the tunica intima. However, on the X-ray the two catheters appear to merge beneath the abdominal wall as the arteries turn caudally in their sheaths between the abdominal wall and the peritoneum. We speculate that the catheter from the left side entered the right umbilical artery via a communicating blood vessel between the two arteries. (Definitive contrast studies at the time of catheterization were impossible because of the baby©s poor clinical condition, with hypotension, oliguria and DIC.) Cord vessels often fork or divide and rejoin, sometimes causing irregular nodularities or false knots over the whole length of the umbilical artery [4]. Furthermore, additional vessels can exist and may be artery, vein (possibly persistent right umbilical vein) or remnants of the vitelline duct. Vitelline vessels are not supposed to have direct communications with the umbilical vessels. In our case examination of the placenta showed normal weight and size, markedly disrupted cotyledons (previa) and a normal vascular pattern with a three-vessel umbilical cord at Pediatr Radiol (1997) 27: 618--621  Springer-Verlag 1997 LETTERS TO THE EDITOR