Ultrasound/MRI Strategy Diagnoses Appendicitis in Kids Without Radiation

By Will Boggs MD

March 04, 2014

NEW YORK (Reuters Health) - Ultrasound followed selectively by MRI can diagnose appendicitis accurately in children, a retrospective study suggests.

"Ultrasound does not expose patients to radiation and should be the first imaging test," Dr. Gudrun Aspelund from Morgan Stanley Children's Hospital and Columbia University Medical Center in New York City told Reuters Health by email. "However, ultrasound is more user dependent than CT or MRI and its sensitivity to diagnose appendicitis is variable. If a diagnosis is still uncertain after history, physical exam, and ultrasound, then an MRI should be considered."

CT has been considered the gold standard for diagnosis of appendicitis, which is the most common indication for acute abdominal surgery in children. MRI has been used in combination with ultrasound for diagnosing appendicitis in adults, but reports of this strategy in children are lacking.

Dr. Aspelund and colleagues reviewed the outcomes of 662 patients under age 18 who came to their emergency department with abdominal pain. An early group - 265 patients - presented when CT was the primary imaging modality. A second group - 397 patients - were seen after ultrasonography followed by MRI for equivocal findings was the standard approach.

In the CT group, 55.4% were positive for appendicitis, of which 19.4% were complicated cases. In the second group, ultrasound was positive for appendicitis in 19.7%. MRI identified an additional 62 cases, seven of which (11.3%) were complicated.

Rates of false-positive imaging (i.e., negative appendectomies) were similar in the first and second groups (2.5% vs 1.4%). There were no false-negatives in either group.

There were no significant differences between the groups in mean overall length of hospital stay, time to antibiotic administration, time to appendectomy, or perforation rate, according to the March 3rd Pediatrics online report.

"Physicians should consider using MRI for the diagnosis of acute appendicitis in children when ultrasound is non-diagnostic," Dr. Aspelund concluded.

"Availability of the various imaging tests at a particular institution and experience with their use and interpretation can affect choice of tests or possible transfer to a different institution," Dr. Aspelund said. "MRI cannot in general be used in children than cannot lie still for long enough (usually children six years old and older can cooperate with the test, which takes about 30 minutes). For the youngest children an ultrasound, followed by CT as needed, would still be used."

Dr. Leann E. Linam is chief of pediatric radiology at Arkansas Children's Hospital, University of Arkansas for Medical Sciences, in Little Rock. She told Reuters Health, "Ultrasound should definitely be the first line imaging modality for the evaluation of possible appendicitis in children. At our institution, we have a protocol that starts with ultrasound."

"Clinical examination by a surgeon is performed before we proceed with any other imaging," Dr. Linam said. "Currently, our next imaging is done with CT. MRI is more expensive, is not immediately available at night and on weekends (our techs take call from home for MRI, whereas CT techs are in-house), and requires sedation in young children."

"Radiation needs to be considered, but in a young child, sedation can be as great a risk," Dr. Linam said.

SOURCE: http://bit.ly/1fCyimX

Pediatrics 2014.

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