There is provided a microcatheter with a tapering wall thickness shaft having varying stiffness/flexibility along its length from proximal end near the medical practitioner to the distal end near the target site in the patient, such as with at least three segments. The shaft is prepared of a thermoplastic material having varying composition along its length. The distal end may be shaped according to the required use just prior to the medical procedure. The microcatheter is particularly adapted for the delivery of microspheric compositions for treatment of tumors or fibroids by embolization of peripheral blood vessels of the tumor or fibroid.
