Side holes at the tip of chronic hemodialysis catheters are harmful.

Side holes at the inflow tip are necessary for acute hemodialysis catheters without inflow end-hole. Most catheters for chronic dialysis, both single and dual lumen, are also provided with side holes. There are no data in support of the notion that side holes improve blood flow or prolong the life of chronic catheters. The opposite may be true. Firstly, the side holes are created by drilling and have rough edges as can be seen in scanning electron microscopy. Secondly, many times, while removing chronic catheters, either electively or because of obstruction, a clot is found at the tip of the catheter and anchored in the side hole(s). Such a clot is difficult to strip by a snare in situ. Thirdly, a difficult to remove clot is formed on the outer surface of the catheter and extends to the inside lumen. If so, the holes have no role in extending the life of the catheter. Fourthly, the heparin or other anticoagulant, which is instilled to the catheter lumen at the end of dialysis, may not reach the catheter tip and/or be leached out in the period between dialyses, thus, predisposing to clot formation at the tip of the lumen. Finally, if the inflow bore is occluded and the blood flows through the side holes, it is likely that the vein intima is sucked into the holes, becomes damaged and causes formation of the mural thrombus. In such a case these holes would not be beneficial in prolonging catheter life, but may even preclude the possibility of inserting another catheter into the same vein at a later date.