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Clinical Observations |
1 Department of Radiology, Hospital of the University of Pennsylvania, 3400
Spruce St., Philadelphia, PA 19104.
2 Department of Surgery, Hospital of the University of Pennsylvania,
Philadelphia, PA 19104.
3 Department of Medicine, Hospital of the University of Pennsylvania,
Philadelphia, PA 19104.
Received January 31, 2005;
accepted after revision March 2, 2005.
Address correspondence to M. S. Levine
(marc.levine{at}uphs.edu).
Abstract
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CONCLUSION. Steep oblique or lateral spot images routinely should be obtained during upper gastrointestinal radiographic studies after gastric bypass surgery to optimize detection of strictures at the gastrojejunal anastomosis.
Keywords: fluoroscopy • gastric bypass surgery • gastrointestinal radiology • obesity • stomach
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Laparoscopic Roux-en-Y gastric bypass surgery (LRGBS) involves creation of a gastric pouch (15-30 mL in size) by transecting and stapling a small gastric segment from the remainder of the stomach. The pouch is anastomosed side-to-side with a loop of proximal jejunum that has been transected, creating a gastrojejunal anastomosis with a short, blindending jejunal stump. A loop of more distal jejunum is then anastomosed side-to-side with the diverted duodenum and jejunum (i.e., the Roux limb), creating a second jejunojejunal anastomosis. Weight loss occurs because the gastric pouch produces early satiety, limiting oral intake, and because the Roux limb bypasses a segment of small bowel, inducing a degree of malabsorption [3, 4].
A frequent complication of LRGBS is the development of strictures at the gastrojejunal anastomosis [5]. Affected individuals typically present 4 weeks or more after surgery with nausea, vomiting, and regurgitation after meals [6]. Prompt recognition of this complication is important because the strictures can be effectively treated by endoscopic balloon dilatation procedures [6].
Upper gastrointestinal radiographic studies have an important role in the evaluation of patients with both early and late complications of LRGBS [7, 8] and can reveal strictures at the gastrojejunal anastomosis in symptomatic patients who may benefit from endoscopic dilatation procedures [8]. It has been our impression that detection of these strictures on barium studies is highly dependent on radiographic projection because of the surgical anatomy. The purpose of our study, therefore, was to determine the optimal radiographic projections for the detection of strictures at the gastrojejunal anastomosis after LRGBS.
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Examination Technique
The radiographic examinations were all performed as single-contrast upper
gastrointestinal studies using digital fluoroscopy equipment. Three patients
initially were given a water-soluble contrast agent (diatrizoate meglumine and
diatrizoate sodium [Gastroview, Mallinckrodt]). These three patients and the
remaining 15 were then asked to ingest varying volumes of a 50%-weight/volume
(w/v) barium suspension (Entrobar, Lafayette Pharmaceuticals), a 250%-w/v
high-density barium suspension (E-Z-HD, E-Z-EM Company), or both.
Water-soluble contrast media were not used for the latter 15 patients because
they had no clinical signs of perforation and had been eating at home. Digital
spot images were obtained with the patients in semiupright or upright frontal,
left posterior oblique (LPO), right posterior oblique (RPO), or lateral
positions. If patients exceeded the weight limit of the fluoroscopic table,
the footboard was removed, and the study was obtained with the patient
standing on the floor beside the tabletop. All of the studies were performed
by one of three attending gastrointestinal radiologists (mean experience, 23.7
years; range, 20-29 years) or by radiology residents, and all studies were
interpreted by the attending radiologists.
Image Review
The radiographic images from these 18 radiographic studies were reviewed
retrospectively by a consensus of two authors (both gastrointestinal
radiologists) who were blinded to the original radiographic interpretations.
The images were reviewed for the presence or absence of a stricture at the
gastrojejunal anastomosis. Our bariatric surgeon creates a staple line at the
gastrojejunal anastomosis that has a luminal diameter of 12-15 mm. Anastomotic
strictures were therefore defined as anastomoses with a luminal diameter of
less than 10 mm. When strictures were present, we assessed the location of the
strictures in relation to the pouch, and we assessed their diameter and length
using a 12-mm barium tablet as a standard to correct for magnification on
small, medium, and large fields of view for the image intensifier on the
fluoroscope. We also assessed whether there was dilatation of the pouch. The
radiologic reports subsequently were reviewed by a third author to determine
whether an anastomotic stricture had been detected at the time of the barium
study and whether there was delayed emptying of barium from the pouch into the
jejunum or reflux of barium from the pouch into the esophagus.
Study Design
When strictures were identified on the radiographic examinations, the
images were reviewed to determine whether the strictures were visible on
frontal, shallow LPO or RPO (defined as < 45° of obliquity), steep LPO
or RPO (defined as > 45° of obliquity), or lateral projections. The
degree of obliquity was determined by assessing the relative projection of the
spinous processes and pedicles of the overlying vertebral bodies. The data
were then analyzed to determine which projections were most useful for
detecting strictures at the gastrojejunal anastomosis. A Fisher's exact test
(S-Plus4, MathSoft) was also performed to determine whether there were
significant differences in stricture detection rates in these various
projections. Endoscopic and medical records were also reviewed by one author
to determine the clinical presentation, treatment, and course.
Institutional Review Board Approval
Our institutional review board approved all aspects of this retrospective
study and did not require informed consent from any patients whose records
were included in our study.
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Seventeen (94%) of the 18 patients with anastomotic strictures after LRGBS underwent endoscopic balloon dilatation procedures. One patient did not undergo a dilatation procedure because of a concomitant marginal ulcer at the gastrojejunal anastomosis. The strictures were dilated to a mean diameter of 13 mm (range, 7-20 mm). Fifteen (88%) of these 17 patients had a marked clinical response with improvement or resolution of their symptoms during a mean follow-up period of 50 weeks (range, 3-150 weeks).
Radiographic Findings
Seventeen (94%) of the 18 patients with endoscopically proven strictures at
the gastrojejunal anastomosis had strictures on barium studies based on the
findings of the original radiologic reports. In retrospect, our review of the
images also revealed a stricture on the barium study in the one patient in
whom a stricture was not mentioned on the original report. There were no other
discrepancies between the original radiologic reports and our retrospective
review of the images in this group of patients.
The strictures had a mean luminal diameter of 4 mm (range, 2-8 mm) and a mean length of 5 mm (range, 2-11 mm). There was delayed emptying of barium from the gastric pouch into the proximal jejunum in nine patients (50%); the pouch was dilated in six of these patients and nondilated in the remaining three. There also was reflux of barium from the pouch into the esophagus in 10 patients (56%). The one patient in whom the stricture was not mentioned on the original radiologic report had no evidence of pouch dilatation or delayed emptying of barium from the pouch.
The gastrojejunal anastomoses were located on the anterior wall of the gastric pouch in 15 (83%) of the 18 patients with anastomotic strictures (Figs. 1A, 1B, 2A, and 2B), on the inferior wall in two (11%) (Fig. 3), and on the anteroinferior wall in one (6%). The strictures were visible on frontal or shallow oblique projections of the anastomotic region in only three (17%) of the 18 patients because of overlap between the pouch and proximal jejunum in these projections (Figs. 1A and 2A). In contrast, the strictures were visible on steep oblique or lateral projections of the anastomotic region in all 16 patients (100%) in whom these projections were obtained (p < 0.0001) (Figs. 1B and 2B). Two patients (11%) could not be placed in steep oblique or lateral positions because of their large body habitus. Thus, strictures at the gastrojejunal anastomosis were significantly more likely to be detected on steep oblique or lateral spot images than on frontal or shallow oblique spot images. All 15 patients with strictures missed on frontal or shallow oblique projections had anteriorly located anastomoses (Figs. 1A, 1B, 2A, and 2B), whereas the three patients with strictures detected on frontal or shallow oblique projections had anastomoses located inferiorly or anteroinferiorly (Fig. 3).
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Upper gastrointestinal radiographic studies are frequently performed for the detection of strictures at the gastrojejunal anastomosis after LRGBS because these examinations are capable of showing even subtle areas of anastomotic narrowing. In a previous study, Blachar et al. [7] described the appearance of strictures at the gastrojejunal anastomosis on barium examinations. To our knowledge, however, the importance of projection for optimizing detection of these strictures on radiographic examinations has not been addressed previously in the radiology literature.
In our study, strictures at the gastrojejunal anastomosis after LRGBS were visible on frontal or shallow oblique (< 45°) spot images from upper gastrointestinal radiographic examinations in only three (17%) of 18 patients (Figs. 1A and 2A). In contrast, anastomotic strictures were visible on steep oblique (> 45°) or lateral spot images in all 16 patients (100%) in whom these projections were obtained (p < 0.0001) (Figs. 1B and 2B). Thus, strictures at the gastrojejunal anastomosis were significantly more likely to be detected on steep oblique or lateral spot images than on frontal or shallow oblique spot images.
The importance of radiographic projection in detecting anastomotic strictures relates to the surgical anatomy in these patients. The gastrojejunal anastomosis is often created via an antecolic, antegastric approach, with the anastomosis located on the anterior wall of the lower end of the gastric pouch because this approach decreases the risk of postoperative internal hernias in comparison with a retrocolic, retrogastric approach [12]. Because of this surgical anatomy, on barium studies strictures can be difficult or impossible to visualize on frontal or shallow oblique spot images as a result of overlap between the lower end of the gastric pouch and adjacent jejunal loops.
In contrast, steep oblique or lateral spot images permit visualization of these anteriorly located gastrojejunal anastomoses in profile, so the strictures are no longer obscured by overlap of the gastric pouch and proximal jejunal loops. In our study, all 15 patients in whom anastomotic strictures were missed on frontal or shallow oblique projections (but visualized on steep oblique or lateral projections) had anteriorly located anastomoses (Figs. 1A, 1B, 2A, and 2B), whereas the three patients in whom the strictures were visible on frontal or shallow oblique projections had anastomoses located inferiorly or anteroinferiorly (Fig. 3), allowing the strictures to be visualized even in these projections.
Unfortunately, obtaining spot images of obese patients in steep oblique or lateral positions after LRGBS can be problematic because the large body habitus of these individuals may cause technical problems in obtaining adequate radiographic penetration for the images and may even prevent the patients from fitting between the fluoroscopy tower and table in a true lateral position. In fact, two (11%) of the 18 patients in our study could not be placed in steep oblique or lateral positions because of their large body habitus. Nevertheless, the radiologists performing the procedures should make every effort to place these patients in the steepest obliquities possible to minimize overlap of the gastric pouch and adjacent jejunum that could obscure strictures at the gastrojejunal anastomosis.
In our study, one or more ancillary signs of obstruction at the gastrojejunal anastomosis (delayed emptying of barium from the pouch into the proximal jejunum and dilatation of the pouch) were detected on barium studies in only nine (50%) of the 18 patients with anastomotic strictures. The one patient in our series in whom the stricture was not mentioned on the original radiographic report had no evidence of pouch dilatation or delayed emptying. It therefore is important to recognize that strictures frequently develop at the gastrojejunal anastomosis after LRGBS in the absence of ancillary signs of obstruction on barium studies. Thus, steep oblique or lateral spot images should be obtained to rule out anastomotic strictures even when there is no other radiographic evidence of obstruction.
Our investigation has the inherent limitations of a retrospective study, including selection bias (we only included patients with proven anastomotic strictures on endoscopy) and interpretation bias (all of the patients whose radiographic images were reviewed had known anastomotic strictures on endoscopy). Nevertheless, the purpose of our investigation was not to determine the sensitivity of barium studies for detecting anastomotic strictures in comparison with endoscopy but rather to determine the value of steep oblique or lateral spot images for showing these strictures. We also recognize that some surgeons who perform LRGBS prefer a retrocolic, retrogastric approach that places the gastrojejunal anastomosis on the posterior wall of the pouch. However, similar overlap between the pouch and proximal jejunum would still be expected on frontal or shallow oblique spot images in patients with a posteriorly located anastomosis, so optimal detection of anastomotic strictures presumably would still be obtained on steep oblique or lateral spot images. Other surgeons occasionally may use surgical techniques in which the gastrojejunal anastomosis is better visualized on shallow oblique or even frontal projections. Thus, the radiographic technique for obtaining an optimal postoperative study ultimately depends on the manner in which the gastric bypass surgery was performed.
In conclusion, our experience indicates that steep oblique or lateral spot images routinely should be obtained during upper gastrointestinal radiographic studies after LRGBS to optimize detection of strictures at the gastrojejunal anastomosis. In patients with antecolic, antegastric anastomoses, such views significantly improve detection of anastomotic strictures by showing the strictures in profile and avoiding overlap between the gastric pouch and adjacent proximal jejunum that could obscure these strictures.
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