An anchoring system for securing a catheter to a patient includes an anchor pad and a retainer. The retainer is supported by the anchor pad and includes a base and a cover. A groove upon the base is arranged to receive a branching site of a catheter where the lumens merge distal to the insertion site. One or more posts also protrude from the base to the cover at a position which will be disposed between the two distal branches of the catheter. The cover closes over the base, securing the branching site between the groove and the posts. The contact between the retainer and catheter thereby inhibits inadvertent motion of the catheter upon the patient. A latch mechanism is disposed upon the retainer to maintain the cover in a closed position over the branching site of the catheter on the base.