One aspect of the present invention relates to a method to control biological fluid flow at a site in a mammal by use of an in situ formed polymer plug. In certain embodiments, the present invention relates to a method to control bleeding following a catheterization procedure, a method to control leakage of cerebral spinal fluid following a lumbar puncture, a method to seal a fistula, or a method to control the flow of serous fluid after a lymphadenectomy. In certain embodiments, the polymer plug is generated in situ by temperature changes, pH changes or ionic interactions. In certain embodiments, the polymer plug comprises at least one optionally purified reverse thermosensitive polymer.
