LAKE BUENA VISTA, FLA. – Ultrasound expedites clinical decision making and often dictates the next step to pursue when managing children in the emergency department.
"It makes sense to use ultrasound for pediatric patients, but there’s been a delay in picking up this idea. Only now is (the use of bedside ultrasonography) becoming more prevalent in pediatric emergency medicine, Dr. Stephanie J. Doniger said at a meeting sponsored by the American College of Emergency Physicians and the American Academy of Pediatrics.
"Among the advantages is that we really never have to perform sedation, and the absolutely most important thing, we don’t need to use ionizing radiation," said Dr. Doniger, director of emergency ultrasound at Children’s Hospital and Research Center, Oakland, Calif.
Still, she said, there are no clear guidelines for ultrasonography’s use in pediatric emergencies. No one body oversees the quality in training or in outcomes. In 2009, ACEP updated its guidelines on bedside ultrasound in the emergency department. The group gave a nod to pediatric use, calling ultrasonography "an ideal diagnostic tool for children ... As in adult patients, emergency ultrasound in children can be life saving, time saving, [can] increase procedural efficiency, and [can] maximize patient safety."
The document says ultrasound is particularly useful in performing the FAST exam, and for bladder evaluations prior to instilling a catheter in infants. Dr. Doniger noted a number of other applications as well.
Ultrasonography is valuable for assessing dehydration by providing a look at the inferior vena cava. "We’re looking here for collapsibility during inspiration. Collapsibility of more than 50% correlates with dehydration."
Appendicitis is tough to image, radiographs are unreliable, and "CTs aren’t great, but we do them if we have to." But ultrasound provides a very good look into what lies beneath, and is one more way to reduce a child’s cumulative radiation dose.
A 2008 study found that a 5-minute bedside ultrasound had a sensitivity of 65% and a specificity of 90% for appendicitis. The positive predictive value was 84%, and the negative predictive value, 76%.
"That might not sound great, but it is a good result to rule in disease. If you have a high suspicion of appendicitis, then use it; if a low suspicion, then don’t."
When looking for an infected appendix, start at the point of maximal tenderness and move to the right while the child is in an oblique position. "It helps if you prop up the hip with some towels," Dr. Doniger said. "The bowel will move away and you’ll have a better view when you compress."
Look for a noncompressible tubular structure with a diameter greater than 6 mm.
The probe can also help find intussusception – a condition that x-rays identify 40%-90% of the time. The ultrasound image of intussusception is target- or doughnut-shaped – a figure formed when the bowel retracts back into itself. A study found that even beginning sonographers can identify this classic sign. Their exams had a sensitivity of 85%, a specificity of 97%, a positive predictive value of 85%, and a negative predictive value of 97%.
Even something that seems innocuous on the surface – like a splinter – will give up its secrets under the ultrasound probe. Foreign bodies may or may not show up on an x-ray, but they are obviously hypoechoic on ultrasound, she said.
Dr. Doniger presented the case of a 13-year-old who thought he got a splinter under his fingernail, but wasn’t sure. He came to the emergency department after his finger became stiff and a little painful. Ultrasound identified the culprit as splinter of wood that was more than 1 inch long.
Guiding the needle during an evaluation for painful hips for effusion is another great use for ultrasound, she said. A 2009 study determined that, compared with ultrasound alone; sonography-guided arthrocentesis for symptomatic hips had 90% sensitivity and 100% specificity, with a 100% positive predictive value and a 92% negative predictive value.
Ultrasound also provides valuable assistance in identifying the landmarks for successful needle placement when performing a spinal tap. A 2007 study equally randomized 46 children to finding the landmarks by palpation or with ultrasound. There were six failed attempts in the palpation group and one in the ultrasound group. Ultrasound was particularly helpful in obese children; four of seven palpation placements failed, compared with no failures in the ultrasound group.
None of the authors declared any financial relationships. The study was funded by the Lynn Sage Cancer Research Foundation, the Avon Foundation, and a private contribution.