title: Incidental physiological sliding hiatal hernia: a single center comparison study between CT with water enema and CT colonography.
abstract: OBJECTIVE
  Hiatal hernia is a well-known factor impacting on most mechanisms underlying gastroesophageal reflux, related with the risk of developing complications such as erosive esophagitis, Barrett's esophagus and ultimately, esophageal adenocarcinoma. It is our firm opinion that an erroneous reporting of hiatal hernia in CT exams performed with colonic distention may trigger a consecutive diagnostic process that is not only unnecessary, inducing a unmotivated anxiety in the patient, but also expensive and time-consuming for both the patient and the healthcare system. The purposes of our study were to determine whether colonic distention at CT with water enema and CT colonography can induce small sliding hiatal hernias and to detect whether hiatal hernias size modifications could be considered significant for both water and gas distention techniques.
  
  
  METHODS
  We retrospectively evaluated 400 consecutive patients, 200 undergoing CT-WE and 200 undergoing CTC, including 59 subjects who also underwent a routine abdominal CT evaluation on a different time, used as internal control, while a separate group of 200 consecutive patients who underwent abdominal CT evaluation was used as external control. Two abdominal radiologists assessed the CT exams for the presence of a sliding hiatal hernia, grading the size as small, moderate, or large; the internal control groups were directly compared with the corresponding CT-WE or CTC study looking for a change in hernia size. We used the Student's t test applying a size-specific correction factor, in order to account for the effect of colonic distention: these "corrected" values were then individually compared with the external control group.
  
  
  RESULTS
  A sliding hiatal hernia was present in 51 % (102/200) of the CT-WE patients and in 48.5 % (97/200) of the CTC patients. Internal control CT of the 31 patients with a hernia at CT-WE showed resolution of the hernia in 58.1 % (18/31) of patients, including 76.5 % (13/17) and 45.5 % (5/11) of small and moderate hernias. Comparison CT of the 28 patients with a hiatal hernia at CTC showed the absence of the hernia in 57.1 % (16/28) patients, including 68.8 % (11/16) and 50 % (5/10) of small and moderate hernias. The prevalence of sliding hiatal hernias in the external control group was 22 % (44/200), significantly lower than the CT-WE and CTC cohorts' prevalence of 51 % (p < 0.0001) and 48.5 % (p < 0.0001). After applying the correction factors for the CT-WE and the CTC groups, the estimated residual prevalences (16 and 18.5 %, respectively) were much closer to that of the external control patients (p = 0.160 for CT-WE and p = 0.455 for CTC).
  
  
  CONCLUSIONS
  We believe that incidental findings at CT-WE and CTC should be considered according to the clinical background, and that small sliding hiatal hernias should not be reported in patients with symptoms not related to reflux disease undergoing CT-WE or CTC: When encountering these findings, accurate anamnesis and review of medical history looking for GERD-related symptoms are essential, in order to address these patients to a correct diagnostic iter, taking advantage from more appropriate techniques such as endoscopy or functional techniques.
authors.affiliation: Department of Radiology, E.O. Ospedali Galliera, Mura delle Cappuccine 14, 16128, Genoa, Italy, matteorevelli@gmail.com.
authors.forename: Matteo
authors.initials: M
authors.lastname: Revelli
authors.forename: Manuele
authors.initials: M
authors.lastname: Furnari
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Bacigalupo
authors.forename: Francesco
authors.initials: F
authors.lastname: Paparo
authors.forename: Davide
authors.initials: D
authors.lastname: Astengo
authors.forename: Edoardo
authors.initials: E
authors.lastname: Savarino
authors.forename: Gian Andrea
authors.initials: GA
authors.lastname: Rollandi
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D023881:Colonography, Computed Tomographic / Q000009:adverse effects*; D003287:Contrast Media; D004733:Enema / Q000009:adverse effects; D005260:Female; D006551:Hernia, Hiatal / Q000000981:diagnostic imaging / Q000209:etiology*; D006801:Humans; D033162:Incidental Findings; D007472:Iohexol / Q000031:analogs & derivatives; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed / Q000009:adverse effects*; D014867:Water
chemical_list: D003287:Contrast Media; D014867:Water; C093233:iobitridol; D007472:Iohexol