Abstract: An apparatus for transcervical sterilization or transcatheter embolization with a controlled bipolar RF catheter for creating thermal lesions in the fallopian tubes or thrombosing vessels has a catheter elongate along an axis thereof with a patient end. The catheter is circular and sized for transcervical insertion into the fallopian tube or transcatheter vessel insertion, respectively. A connector on an end of the catheter opposite the patient end has the terminations for RF and monitoring and is shaped for the surgeon to manipulate during placement and withdrawal. Two or more bipolar electrodes on the patient end are placed so each electrode is spaced from another with each circumscribing the catheter. A mucosa or thrombus sensor responsive to applied RF energy passing between the two or more bipolar electrodes determines the condition of the transmural formation of a lesion or the thrombus between each of the electrodes.