Marcus Oosenbrug, MD

Provider is directly employed by MedStar Health

Marcus Oosenbrug, MD, FRCSC, is a double-board-certified colorectal surgeon at MedStar Georgetown University Hospital, where he provides advanced surgical care for patients with benign and malignant diseases of the colon, rectum, and anus.

Dr. Oosenbrug treats the full spectrum of colorectal conditions, including colorectal cancer, inflammatory bowel disease (Crohn’s disease and ulcerative colitis), and diverticulitis; anorectal conditions, in particular hemorrhoids, fissures, fistulas, and anal dysplasia; and pelvic floor disorders such as rectal prolapse and fecal incontinence. Trained in minimally invasive techniques, including laparoscopic and robotic approaches, he strives to help patients recover more quickly and with less pain, while preserving normal function whenever possible.

Dr. Oosenbrug's clinical interests include complex inflammatory bowel disease and sphincter-preserving procedures such as J-pouch surgery. He is also passionate about LGBTQ+ health, and the early detection and treatment of anal dysplasia using high-resolution anoscopy (HRA), a proven method for reducing the risk of anal cancer in vulnerable populations. He is also trained in sacral nerve stimulation therapy (MedTronic Interstim™) for fecal incontinence.

Originally from Canada, Dr. Oosenbrug completed his medical degree at McGill University in Montreal and general surgery residency at the University of Toronto. Before joining MedStar Health, he completed a fellowship in Colon & Rectal Surgery, as well as an additional year of further advanced surgical training in minimally invasive and complex reoperative colorectal surgery at the Cleveland Clinic in Florida.

A strong advocate for patient-centered care, he is dedicated to fostering an inclusive, affirming, and respectful environment for all patients and works closely with multidisciplinary teams of gastroenterologists, oncologists, and gynecologists to deliver comprehensive, coordinated care.

Having adopted Washington, D.C. as his home, he enjoys traveling, exploring new restaurants, and discovering everything the diverse capital city has to offer.

Philosophy of Care

“I strive to treat every patient with the same honesty, compassion, and attention I would give my own family. Trust and continuity of care are essential in my field, and I want patients to know that I’m here to support them throughout their entire healing journey. I see myself as an advocate for my patients, and my goal is to create a welcoming environment where people from all walks of life can feel heard, supported, and empowered to make informed decisions about their care.”