I am originally from Cambridge, Massachusetts. I practiced in Quincy for 30 years before coming to South Shore Medical Center in 2002. I am experienced in abdominal surgery, trauma, and management of skin and soft tissue tumors. 

I graduated from Tufts University and received my medical degree from Albany Medical College in Albany, NY. I completed my surgical and urological residencies at Massachusetts General Hospital. I am certified by the American Board of Urology and I strive to provide the highest quality patient care in a warm compassionate environment.

William Tollefsen, MD is the EMS and MIH Medical Director for South Shore Health. Dual-boarded in Emergency Medicine and EMS Medicine, Dr. Tollefsen works clinically as an Emergency Physician at South Shore Health in addition to his role as EMS Medical Director.

One of few physicians in the country to receive the prestigious "FAEMS" recognition, Dr. Tollefsen is also the Medical Director for OEMS Region IV, serving 61 cities and towns of the Metro-Boston EMS Council. As the current EMS Medical Director for eight municipal and three private ambulance services on the South Shore, Dr. Tollefsen interacts and provides oversight for over 400 Paramedics.

Dr. Tollefsen graduated from New York Medical College and completed residency training in Emergency Medicine at Harvard University, Brigham and Women's, and Massachusetts General Hospital. He completed a fellowship in Emergency Medical Services and Critical Care Transport at the University of Massachusetts, where he worked as an Emergency Physician and Flight Physician for UMASS LifeFlight. He completed an MBA at the Isenberg School of Management at UMASS Amherst, and holds a Master of Medical Science degree from the Boston University School of Medicine.

A former pre-hospital provider, he is actively involved in EMS system design, paramedic education and Critical Care Transport Systems. He works closely with multiple EMS, Fire and Law Enforcement agencies throughout Massachusetts.

His research interests include systems of care, resuscitation, airway management, and paramedic education.

I love caring for children and their families, whether it be supporting parents as they learn how to care for their newborns or helping a sick child recover from an acute illness. I believe in shared decision-making and incorporating each family's individual needs and goals into their child's care. Outside of work, I enjoy spending time with family, running, and traveling.

My treatment philosophy and focus is to diagnose and treat patients ages 15 – 100 whom have a variety of breast issues including but not limited to infection, pregnancy related breast issues, genetic risk for cancer, abscesses, skin disorders, abnormal breast imaging, breast lumps, and past or current personal history of breast cancer.

I've been an RN since 1981, working in Internal Medicine, Oncology, and Ventilator Care. I've been a NP since 1996. I'm a graduate of Columbia University in Adult Health and Oncology. I worked in New Jersey for 20 years in Internal Medicine and combined Oncology prior to relocating to Massachusetts in 2003.

Certified by ANCC, ONCC, ANCC.