LETTER TO THE EDITOR Re: Colonic perforation during screening CT colonography using automated CO 2 insufflation in an asymptomatic adult Emanuele Neri, 1 Andrea Laghi, 2 Daniele Regge 3 1 Diagnostic and Interventional Radiology, University of Pisa, Via Roma 67, 56100 Pisa, Italy 2 Radiology Unit (ICOT/Latina), Department of Radiological Sciences, University of Rome ‘‘La Sapienza’’, Rome, Italy 3 Radiology Unit, Institute for Cancer Research and Treatment, Candiolo, Turin, Italy Dear Editor, We would like to comment on the article by Bassett et al. [1] on a case of perforation occurred after auto- matic insufflation of CO 2 , in an asymptomatic patient with diverticular disease. The authors report that the insufflation was carried out by delivering approximately 11 L of CO 2 with pressure at the equilibrium of 25 mmHg. We believe the delivery of such a large volume of gas must be carefully assessed in these patients. The presence of diverticula represented certainly a risk factor. Diverticula are saclike protrusions in the colonic wall that develops as a result of herniation of the mucosa and the submucosa through ‘‘points of weakness’’, where the vasa recta penetrate the muscular layer; they are more common in the sigmoid colon (in 5%–10% of cases the whole colon is involved). Diverticula represent closed chambers of the colonic lumen delimited by a thin mucosal wall with low resistance to stretching; therefore, in this specific case perforation more likely occurred within a diverticulum, as the authors report. The inci- dence of diverticula is around 30% in patients over 50 years of age [2]; most people with uncomplicated colonic diverticulosis are asymptomatic; therefore, the risk of perforation cannot be estimated before CTC (except in patients that underwent previous colon imaging tests). In summary we believe that even in asymptomatic patients perforation cannot be totally excluded (even if very rare) and careful bowel distension must be adopted.A further important aspect is the operator (who performs the insufflation). In this case it was a technologist. While the technologists, can be trained to perform safely the pro- cedure, we believe that in risk patients a medical doctor should monitor the patient directly in the CT room and even more take directly the responsibility to perform the insufflation. Especially in patients with symptoms of a possible partially obstructing colonic lesion, known hernia that might involve the colon, recent colonic pol- ypectomy or biopsy, known underlying colon disease, difficulty in inserting the rectal tube, and elderly or frail patient status, would be appropriate for medical radiol- ogist to assess the patient during the procedure [3]. In our institutions, the insufflation is made by the radiologist or by the resident, using however much smaller volumes than those reported in the case of Bassett et al., ranging from 3 to 4 L. During the insufflation the abdomen of the patient is palpated and the degree of tension and abdominal distension is evaluated. At the same time the patient is asked to report any symptom that occur and provide a tolerance feedback. We would finally point out that the insufflation can cause vaso-vagal reactions linked to stimulation of the vagus nerve, which follow the stretching of the vagi fibers. It comes obvious that the administration of large volumes of gas may increase the risk of vaso-vagal reactions, characterized by hypoten- sion, bradycardia, nausea, vomiting, to the most serious cases of syncope; these events should be immediately recognized and treated by the radiologist, as they represent a true medical emergency [4]. The authors reported the case of an asymptomatic patient, evaluated under a screening program. Submitting the case appears very appropriate because the increasingly wide use of CT colonography for screening programs certainly will increase the risk of complications. We agree with the authors that CT colonography is safe with a low incidence of complications such as perforation and, as the authors emphasize, the advantage of CTC compared Correspondence to: Emanuele Neri; email: neri@med.unipi.it ª Springer Science+Business Media, LLC 2008 Published online: 11 June 2008 Abdominal Imaging Abdom Imaging (2008) 33:748–749 DOI: 10.1007/s00261-008-9429-z