New signs of gastric band slippage identified

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A study of patients with a slipped gastric band has found two previously undescribed radiographic signs of the complication that could be used to help diagnose affected bariatric patients.

The new signs include inferior displacement of the superolateral gastric band margin from the diaphragm by more than 2.4 cm and the presences of an air-fluid level above the gastric band on an upright frontal radiograph obtained before barium ingestion, according to the study published in the July issue of American Journal of Roentgenology.

Authors David W. Swenson, MD, of the Alpert Medical School of Brown University in Providence, R.I., and colleagues added that the two newly identified signs of gastric band slippage are actually more sensitive and specific than previously identified signs.

Laparoscopic adjustable gastric banding accounted for up to 42 percent of bariatric surgery in 2008, and while it’s been shown to result in weight loss with favorable morbidity rates, band slippage is a complication that’s been reported variously in 2-36 percent of adjustable gastric banding patients, according to Swenson and colleagues.

There were previously two telltale radiographic signs indicating a slipped gastric band is more likely: an abnormal vertical or horizontal orientation relative to the midsagittal plane through the thoracic spine (the phi angle), and when the band’s central lumen is more likely to be visualized than its superimposed sides (known as the “O sign”).

Swenson and colleagues compared these known signs to the newer radiographic signs by retrospectively identifying 21 patients with a surgically proven slipped gastric band along with 63 randomly selected asymptomatic gastric band patients who had undergone barium swallow studies.

Results showed inferior displacement of the superolateral band margin by more than 2.4 cm from the diaphragm was 95 percent sensitive and 97-98 percent specific, while the presence of an air-fluid level was 95 percent sensitive and 100 percent specific. This trumps the traditional signs, as an abnormal phi angle lacks specificity, while the O sign has a low sensitivity for band slippage.

The authors noted that even though imaging evaluation for gastric band slippage typically involves a barium swallow study, all four signs of gastric band slippage are evident on upright frontal scout radiographs. “Although our study did not evaluate the performance of frontal radiographs alone for the diagnosis of gastric band slippage, this observation is significant given that some patients with gastric bands may present as outpatients or in an emergency department setting with symptoms that prompt clinicians to order chest or abdominal radiography,” wrote Swenson and colleagues.