In this age of specialization most patients with diseases of the hind gut and anus are still managed by general physicians or surgeons. The speciality of coloproctology has grown from the art of 'anology', a study of conditions limited to that distance from the anal verge that could be inspected easily by torch- or candlelight or with the aid of a simple speculum. Two centuries ago many proctological ills were often treated by itinerant quacks, partly because the physician considered himself rather too grand to meddle around the anus and the medical profession in general tended to look down on those who studied anal disease. Today, in certain countries, coloproctology has become a speciality every bit as exclusive as urology or orthopaedic surgery, with its own training programme and examinations, usually undertaken after the end of general surgical training. Such super-specialization has undeniable advantages with rapidly advancing technology and therapeutic possibilities. There is no doubt that for the patient suffering from a low rectal carcinoma or severe inflammatory bowel disease there are advantages in being treated by surgeons who are dealing with several cases in a year rather than by a general surgeon who sees such problems relatively rarely. Such specialized colorectal surgery units makes good sense medically and economically in large centres of population with good communications.

2-D and 3-D anal ultrasound are among the most recent and advanced tools available for both the diagnosis and the management of anorectal diseases. They are neither expensive nor harmful for the patients and progressively replaced anal mapping with EMG electrodes for the diagnosis of sphincter's defects and anismus, which represents nearly 50% of the cases of chronic constipation. Anal US may provide the clinician with useful information for both classification, diagnosis and management of anorectal sepsis, anal incontinence and anorectal-perineal chronic pain. Almost any case presented in this Atlas shows both imaging and clinical pictures, thus allowing both the radiologist and the clinician to assess the reliability of the exam and the outcome of the selected treatment.