Weight limits restrict imaging needs of obese gastric bypass patients

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CHICAGO, Nov. 27—Weight limits of CT and fluoroscopy imaging systems need to be increased to address the needs of obese gastric bypass patients, according to a study presented today at the 93rd annual meeting of the Radiological Society of North America (RSNA). The study findings show that patients who suffer complications after gastric bypass surgery may face further health risks because of their weight exceeds the limits of diagnostic imaging equipment.

"When patients weigh more than 450 pounds, standard diagnostic imaging often cannot be used," said Raul N. Uppot, MD, an assistant radiologist at Massachusetts General Hospital (MGH) and instructor of radiology at Harvard Medical School in Boston. "In these cases, physicians must resort to other means of diagnosis such as exploratory surgery or using less accurate or more invasive techniques."

According to the Centers for Disease Control and Prevention, nearly one-third of the American population is obese. Along with the rise in obesity has come an increase in the number of gastric bypass procedures performed. Like any surgical procedure, gastric bypass is not without risks. Most common complications include suture tears and leaks, pulmonary embolism, pneumonia and infection and serious complications tend to be more prevalent among the severely overweight.

Uppot and his colleagues at MGH conducted an eight-year retrospective study of all patients weighing more than 450 pounds who underwent a gastric bypass procedure at the hospital between June 1999 and April 2007. Patient imaging usage and clinical course were tracked using electronic health records and evaluated to determine the outcomes of those who, based on their weight, were denied their physicians' first choice of imaging. The maximum weight limit for a CT table at the time of the study was 450 pounds, although at least one vendor now has a CT table that can accommodate a 650 pound patient.

The results show that 12 (27 percent) of the 44 patients who weighed more than 450 pounds required postsurgical imaging due to a clinical condition, but were denied because their weight exceeded the limit for the imaging equipment. Four patients who could not be evaluated with imaging for suspected leaks had to return to the hospital for surgery and two additional patients with suspected lung blood clots could not undergo a chest CT. Of two patients who came in with nonspecific abdominal pain, one was evaluated with ultrasound and the other one had a barium swallow test. Because imaging was not an option, one patient who suffered trauma underwent exploratory surgery in lieu of noninvasive imaging. Another patient was denied a chest CT and received no further imaging evaluation, according to the findings.

"When obese patients cannot be diagnosed using standard-of-care imaging techniques, then other diagnostic measures have to be instituted," Uppot said. "Patient care may be ultimately affected due to a compromised diagnosis."