The introduction of two-dimensional and three-dimensional endorectal ultrasonography has increased the diagnostic accuracy in staging and follow-up of anal and rectal tumors. As a consequence of the recent and continuous developments in diagnostic imaging, major advances have also been made in the field of surgery, with the advent of laparoscopic, robotic and microscopic transanal interventional techniques, and in oncology with the utilization of neoadjuvant chemotherapy and intraoperative radiotherapy. Written by internationally renowned experts in the field of endoanal and endorectal ultrasonography, this atlas provides a complete overview of different neoplasia and will be a useful companion in everyday clinical practice. The chapters are divided into three main parts illustrating: - the basic principles of ultrasonography, techniques of endoanal and endorectal ultrasonography, and surgical and endosonographic anatomy of the anal canal and rectum; - the ultrasonographic staging of anorectal tumors with numerous endoscopic, radiologic, operative, and histological illustrations; - surgical and oncological therapeutic strategies. Considering the wide range of topics covered, the volume is of interest to surgeons, coloproctologists, radiologists, gastroenterologists, oncologists and radiotherapists.