Pocket-sized ultrasound for DVT: Not just for EDs anymore

Just as he was about to be discharged from the hospital’s internal medicine department, the 71-year-old patient reported swelling in one of his legs. When the patient had presented to the hospital several days before, he was diagnosed with acute renal failure and probable retroperitoneal fibrosis. But the obstructive nephropathy had since resolved and he was pre-scheduled for further workup and treatment for the retroperitoneal fibrosis.

So, why did he have this unexpected unilateral leg swelling?

“The symptoms were highly suspicious for deep vein thrombosis,” noted internal medicine physician Michael Wagner, MD, of the University of South Carolina School of Medicine and Palmetto Health hospital, Columbia, SC.

Because accurate and timely diagnosis and treatment best prevents morbidity and mortality in deep vein thrombosis (DVT), Dr. Wagner—along with fourth-year medical student Elizabeth Baker—used a pocket-sized ultrasound (PSU) device to perform a limited compression ultrasound of the patient’s common femoral and popliteal veins.

The patient’s veins weren’t compressible, they found, and the PSU showed echogenic material inside the lumen. They cancelled the patient’s discharge and started him on anticoagulation therapy immediately. A formal duplex ultrasound later confirmed the diagnosis of lower extremity DVT.

“The rapid diagnosis of deep vein thrombosis allowed treatment initiation and coordination of outpatient management a day prior to the formal study and shortened overall hospitalization,” they wrote in a Letter to the Editor about this case, published in The American Journal of Medicine.

Feasible and accurate

Currently, point-of-care ultrasound is used mostly in emergency and surgical settings to get a faster jump on treatment. But interest is growing among hospitalists and internists due to the device’s portability and convenience at bedside, Dr. Wagner noted.

“Dozens of medical schools now include ultrasound teaching at the undergraduate level, and we would expect popularity of PSU to increase over time,” he said. “As it becomes integrated into learning at all levels, the PSU could become as ubiquitous as the stethoscope—though this is likely several years away.”

Previous research has shown that PSUs are feasible and accurate, with 100% sensitivity and specificity compared to standard ultrasound for imaging DVT in the iliac, femoral, and/or popliteal veins.

In addition, “PSU units have been refined in the past decade, coming down in price while the image quality and ease of use has improved,” Dr. Wagner said.

Limited compression ultrasound for DVT is simple to perform and usually takes less than 2 minutes per limb, he added.

“Our program will detect about 5 or 6 DVTs with a PSU in a given academic year, in both the inpatient and outpatient settings,” he said.

Appropriately trained physicians—including internists and hospitalists—can use PSUs to benefit their patients.

“Familiarity with arterial and venous anatomy as well as proper training is essential,” Dr. Wagner explained. “More awareness of the potential of this emerging technology is needed in specialties like internal medicine, and we should work with our medical societies, nationally and locally, to ensure these training opportunities exist.”

Indeed, the only thing delaying more widespread use of PSUs is not machine cost or portability, he noted, but training in their use.

For internists looking for courses and training in point-of-care ultrasound, Dr. Wagner suggested:
• Society of Ultrasound in Medical Education (SUSME)
• American Institute of Ultrasound in Medicine (AIUM)
• Society of Hospital Medicine (SHM)
• American College of Physicians (ACP)

The University of South Carolina School of Medicine also offers a 2-day CME course as an introduction to primary care ultrasound, he added.

Dr. Wagner and Ms. Baker received no support nor have any financial interest in companies that manufacture pocket-sized ultrasound devices.