and authoritative tome in the grand tradition of Philip Gordon and Santhat Nivatvongs. Building on the widely acclaimed previous editions' reputation for superb quality and reader-friendliness, the fourth edition includes contributions from an expanded cadre of internationally known experts. Significant advances have been made in this field since the third edition was published. The latest diagnostic modalities are highlighted such as MRI, CT angiography, and enterography. The first section covers essentials such as anatomy, physiology, diagnosis, colonoscopy, and patient management. Sections two through four discuss a full spectrum of anorectal diseases, colorectal disorders, trauma, unexpected challenges, and complications. Among the additions are expanded sections on transanal total mesorectal excision, genetics, personalized medicine, "wait and watch" principles, outpatient management of anorectal surgery, and large bowel obstruction.