A vaginal probe includes a metal detection sensor for detecting the presence of ferrous-laden endometriotic tissues. The probe is electrically connected to external electronic circuitry for interpreting the readings taken by the sensor and for providing a qualitative or quantitative measurement of the amount of endometriotic tissues present. The probe is inserted in either the vagina or peritoneal cavity of a patient to detect the location and the relative amounts of iron or ferrous-laden tissues in the pelvic area of the patient. Using the probe and monitoring the readings over time as part of pelvic exams assists in determining the early onset or progression of endometriosis and/or the response to one or more therapies being provided to the patient to treat the disease.