Peter William Callen

1947 - 2025

Peter William Callen
08/08/1947 - 12/14/2025
Peter W. Callen, MD August 8, 1947 - December 14, 2025
Peter W. Callen, MD, of Mill Valley, California, passed away on December 14, 2025. He was 78 years old.
Born on August 8, 1947, Peter dedicated his life to his family, as well as to medicine, education, and the service of patients and learners alike. After earning his medical degree from the University of California, San Francisco, in 1973, he completed his residency in Diagnostic Radiology and fellowship training at UCSF, where he spent the rest of his career.
A respected radiologist, teacher, and scholar, Peter helped define the field of obstetric and gynecologic ultrasound through decades of clinical practice, research, and teaching. His work focused on improving sonographic detection of abnormalities and reducing false positive diagnoses, with a particular interest in fetal imaging. He authored more than 200 peer-reviewed articles and 65 book chapters, advancing clinical understanding across generations of clinicians. He was perhaps best known for his textbook Ultrasonography in Obstetrics and Gynecology, a seminal clinical reference that became one of the most widely used resources in its field worldwide.
Beyond his professional accomplishments, Peter was cherished for his generosity, kindness, sense of humor, and genuinely disarming presence. Despite his many accolades and influence on the field, he was humble to the core, the kind of person who made everyone around him feel at ease, whether in clinical teaching, scholarly discussion, or everyday conversation.
He is survived by his loving wife, Karen Callen; his children, Melanie Callen, Brooke Callen, Andrew Callen, and Daniel Callen; his grandchildren, Lula McMullin, Liam Callen, Jackson Callen, and Rory Callen; and his older brother, John Callen.
Peter's legacy lives on not only in the many clinicians and students he taught, but in the generosity of spirit he showed every day of his life.
Services will be held in Marin County, California, with details to be shared by the family.