Browse Stanford University | Stanford Profiles

John V. Gahagan, MD, FACS, FASCRS

Clinical Associate Professor, Surgery - General Surgery

BioJohn V. Gahagan MD is a Clinical Associate Professor in Colon & Rectal Surgery. He leads the Colon & Rectal Surgery residency program as Program Director and serves as Chief of Surgery and the Medical Director of Supply Chain at the Stanford Tri-Valley Hospital. He joined Stanford in 2019 to build the Stanford Colon & Rectal Surgery practice in the East Bay at Stanford Tri-Valley in Pleasanton and at Stanford Health Care – Emeryville. He has training in advanced minimally invasive surgical techniques including robotic and laparoscopic surgery. He has authored several textbook chapters and original articles in peer-reviewed journals. His clinical practice is focused on the surgical treatment of colon and rectal cancers, inflammatory bowel disease (ulcerative colitis and Crohn’s disease), and benign colon and anorectal diseases (diverticulitis, hemorrhoids, fistulas, fissures). He believes in patient-centered care and multi-disciplinary approach to the treatment of diseases of the colon, rectum and anus.

Dr. Gahagan is passionate about surgical education. He serves as an Associate Program Director of the Stanford General Surgery Residency Training Program. In that role, he oversees resident evaluation and feedback. He led the revamp of the program’s evaluation process and Clinical Competency Committee – work that has been presented at the Association of Program Directors in Surgery (APDS) and the Accreditation Council for Graduate Medical Education (ACGME). In 2021, he established the Stanford General Surgery Endoscopy rotation, giving general surgery residents an opportunity to gain endoscopy experience by collaborating with faculty gastroenterologists and fulfilling their graduation requirements. In 2026, he established the Colon & Rectal Surgery residency program at Stanford and serves as the Program Director. At the time of accreditation, this program was the only ACGME accredited Colon & Rectal Surgery residency program in Northern California. In addition, he is the General Surgery Rotation Director for the Stanford Tri-Valley Family Medicine Residency. On a national level, he is an associate question writer for the American Board of Colon & Rectal Surgery and serves on the USMLE Step 3 Test Development committee and the USMLE Management Committee.

He also serves in various administrative roles, including as Chief of Surgery at the Stanford Tri-Valley Hospital. In 2025, he was appointment Medical Director of Supply Chain for the Stanford Tri-Valley Hospital. He is a member of the Stanford Medicine Partners Quality and Credentialing Committee, the Stanford Tri-Valley Operating Room Committee and the Stanford Tri-Valley Medical Executive Committee.