Initial Influence of Right Versus Left Lateral Recumbency on the Radiographic Finding of Duodenal Gas on Subsequent Survey Ventrodorsal Projections of the Canine Abdomen

Abstract

Identification of the duodenum and potential abnormalities on survey abdominal radiographs is often difficult unless it contains gas. This study investigated the effect of patient positioning on the presence of duodenal gas in survey abdominal radiographs. One hundred dogs receiving a three-view survey abdominal radiographic study were enrolled in a prospective, randomized study where all dogs were divided into two groups. Group A (n = 51) dogs had a left lateral projection first, followed by a ventrodorsal projection, ending with a right lateral projection. Group B (n = 49) dogs had a right lateral projection first, followed by a ventrodorsal projection, ending with a left lateral projection. The presence of gas within the duodenum and level of distribution of gas throughout the duodenum were recorded for all three projections. In addition, the presence or absence of duodenal pseudoulcers was evaluated on all three projections for each dog. The results for the two groups were compared using Chi-square analysis with a P-value of less than 0.05 being considered significant. Results showed that dogs first placed in left lateral recumbency were significantly more likely to have duodenal gas on the subsequent ventrodorsal and right lateral radiographic projections compared to dogs first placed in right lateral recumbency (P-value < 0.0001). Pseudoulcers were seen in 11 dogs that had duodenal gas making the visualization of pseudoulcers on survey abdominal radiographs somewhat commonplace. This study emphasizes the benefit of using initial left lateral abdominal projections prior to other views for subsequent evaluation of the duodenum.

Clinical findings and results of diagnostic imaging in 82 dogs with gastrointestinal ulceration

“…A gastric or intestinal ulcer is unlikely to be visible in survey radiographs but duodenal pseudoulcers may be observed in survey radiographs, particularly in dogs positioned in left lateral recumbency (Vander Hart & Berry ). These structures, which may also be identifiable in ultrasound and CT images, may be distinguished from true ulcers because they are normally multiple, evenly spaced and occur on the anti‐mesenteric border of the descending duodenum, whereas the majority of duodenal ulcers occur near the cranial duodenal flexure and pyloric canal (Stanton & Bright ).…”

Utility of two‐view vs. three‐view abdominal radiography in canines presenting with acute abdominal signs

“…This is particularly surprising as most subjects presented here had gastrointestinal foreign material with or without mechanical ileus and a prior collection of case reports demonstrated the increased diagnostic utility of the left lateral view, in addition to the right lateral view, for a selection of similar cases . Authors of a recent study comparing the distribution of gas within the duodenum based on initial right‐ vs. left‐ lateral recumbency speculated that the new two‐view standard abdominal radiographic study could include left lateral and ventrodorsal views for cases where gastrointestinal obstruction is suspected or needs to be ruled out . Our findings would support this as it seems any previously inferred increased diagnostic accuracy for such cases is more likely related to having obtained a left lateral view at all (i.e., as part of a two‐view examination), rather than in addition to initial right lateral and ventrodorsal views.…”

“…Variability in the appearance of the stomach and particularly the pylorus with regard to laterality of the acquired images has been demonstrated . A recent publication demonstrated that the order in which radiographs are obtained also changes the typical distribution of gas within the gastrointestinal tract and hence would be implied to affect the ability to identify lesions and arrive at a correct diagnosis . Differences in the appearance of organs, such as the spleen, have also been noted.…”

“…While a few veterinary academic institutions have transitioned to a standard three‐view abdominal radiographic study protocol (personal communication with veterinarians familiar with imaging sections at University of Florida, University of Georgia, University of Illinois, and others), obtaining only two views of the canine abdomen remains the most common abdominal protocol in veterinary practices. The authors speculate this change from two‐ to three‐view studies of the abdomen is partly based on available data, but mostly on anecdotal information as a recent online search (Pubmed and Google Scholar using the key words “comparison”, “accuracy”, “2‐view”, “two view”, “3‐view”, “three view”, “abdom*”, “radiograph*”, “canine”, “dog”, “left lateral”, “right lateral”, “thoracic”, and “thorax” from 1963 to present) revealed no statistical analysis conducted to prove the increased accuracy or confidence of the reviewer in diagnosing gastrointestinal disease, or any other disease, with three‐view abdominal radiography. If three‐view abdominal radiography increases the diagnostic accuracy of detection of common gastrointestinal diseases, this may decrease the need for more expensive and less available alternative imaging techniques, such as computed tomography or ultrasound, or potentially avoidable surgical intervention to achieve a diagnosis.…”

Performing both lateral abdominal radiographs may not improve the visualization of gas in the gastric outflow tract of cats

“…Some evidence in dogs support acquiring both the right and left lateral recumbent views, making three‐view radiographic studies increasingly common . Inclusion of a left lateral view as part of the standard protocol in dogs improves visibility of the gastric outflow tract due to positioning of gas within its non‐gravity dependent lumen to allow better assessment of diameter as well as the presence of any nonmobile radiopaque luminal content such as foreign bodies to be highlighted by gas serving as negative contrast . It was additionally shown in canine patients that gas is best distributed to the pyloric antrum and duodenum when the left lateral view is obtained first .…”