I grew up in a small town in Northern New York, and joined South Shore Hospital and Brigham and Women's Hospital in 2012. I completed my undergraduate and medical education as well as my general surgical training and surgical critical care fellowship at the University of Rochester in Rochester, NY. I am also fellowship trained in minimally invasive and bariatric surgery from Dartmouth Hitchcock Medical Center. I have had a long-standing passion in bariatric and weight-loss surgery and my goal in joining the South Shore Hospital team was to bring that expertise and opportunity to the South Shore community. The hospital has been very supportive in this endeavor and over the past few years we have created a collaborative team of providers from across institutions to start the South Shore Hospital Center for Metabolic and Bariatric Surgery. As medical director it has been my pleasure to help the program grow into a strong clinical component  of the department of surgery and create more outreach into the community. I am also actively engaged as a trauma surgeon and have a busy general surgery practice taking care of a variety of disease processes including the minimally invasive management of gallbladder disease, hernia, GERD, hiatal hernias, as well as the surgical management of a variety of other gastrointestinal disorders. When I am not working, I enjoy the simple things in life like relaxing by a large campfire or spending the day at the beach with my family. 

My goal is to help patients and families manage the acute illness that lead to hospitalization and transition to a healthy life outside the hospital environment.

I am passionate about effective management of acute medical issues while providing clear and concise medical information. In addition to clinical practice, I am interested in using technology innovations to improve patient health.

Outside of work, I am an avid SCUBA diver. 

It has been my privilege to practice medicine and to have made a difference in the lives of my patients over the past 21 years. I enjoy the challenges of practicing internal medicine in a hospital setting and working as part of a team with our excellent hospitalist providers, consultants, nursing and ancillary staff. I served as Medical Director of the Hospitalist Department from 2009-2015 and am proud to say that we have an amazing program with dedicated clinicians who genuinely enjoy the care of hospitalized patients and are committed to excellence in their every day work. I enjoy giving back by participating in the Pan Mass Challenge which raises critical funds for cancer research and the Multiple Sclerosis cycling events. I enjoy boating, hiking and camping, and long distance bicycling and, most importantly, spending time with my family.

My philosophy is to engage patient is their own care.

I completed my residency at Cambridge Health Alliance in Cambridge, MA, often caring for underserved populations and immigrants.  I believe in engaging the patient in their own care and understanding any difficulty they may have in caring for themselves.

I graduated from Colegio Nacional de San Isidro in Buenos Aires, Argentina and completed my medical degree at Buenos Aires University School of Medicine. My surgical and urological residency were spent at the Hospital Italiano in Buenos Aires. I was an attending Urologist at Hospital Roffo in Buenos Aires until I came to the United States. At that point I was a Urology Fellow working on a research project at the Children’s Hospital and Harvard Medical School in Boston. I completed my American residencies in urology and surgery at the University of Massachusetts.

I enjoy spending time with my wife and three children.

As an admitting hospitalist, my focus is to facilitate a smooth transition between the emergency department and the inpatient  admission. 

Waiting to be admitted to the hospital can be nerve wracking, emotional, and even scary. My goal is to ease  your transition from waiting in the ER to being admitted, explain your condition, and answer all questions you may have. Raised and educated locally, it is my pleasure to serve this wonderful community of people who call the South Shore home. In my free time, I enjoy traveling, spending time with family and friends, and exploring/discovering all that the area has to offer.   

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 have been a proud member of the Hospitalist group at South Shore Hospital since its inception in 2000. I believe that patients can benefit from a dedicated group of hospital physicians who work in conjunction with the primary care physicians and specialists in the community.  

Outside of work, I enjoy most sports and outdoor life with my family on a small farm in Southern New Hampshire.

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.