5 Minute Sono Soft Tissue - Click to Learn More

5 Minute Sono MSK - Click to Learn More

Clinical Indication

Abscess, cellulitis, joint effusion (Arthrocentesis), suspected cyst

Probe Selection

Linear for soft tissue and MSK, Curvilinear for Abdomen and Thorax

Tips

• Measure fluid collection if present, use transverse and longitudinal views to get a 3-dimensional measurement for total volume. 

• Use a surgical marking pen to indicate your needle insertion point based on your scan.

• Use more gel and less pressure when scanning an abscess as these are very painful.

• Consider water bath for painful/superficial structures

• Can also use IV bag or glove filled US gel or water to create an acoustic stand-off pad

Notes

• Cellulitis

  • Will appear as thickened hyperechoic skin with echogenic subcutaneous tissue

  • Cobblestoning: Reticular hypoechoic edema traversing subcutaneous fat

    • Very sensitive, but not specific for cellulitis

    • Can look at lymph nodes to see if you have increased flow to clue into possible reactive edema

• Abscess

  • Sonographic fluctuance: gentle pressure will show movement of pus

    • pathognomonic for abscess

  • Pearl: use color flow before you cut to ensure that there is no vessels in close proximity or the structure of interest is not vascular

  • Special Considerations: Breast

    • Warrants referral for MRI, Mammogram, comprehensive US as this is a unique glandular structure. It may be beneficial to look with POCUS, but needs further evaluation

    • Cancerous lesions will appear complex, vascular, have calcifications

• Necrotizing Fasciitis

  • Subcutaneous air: appears hyperechoic with dirty shadowing

  • STAFF exam for necrotizing fasciitis: subcutaneous air and free fluid

• Foreign Bodies

  • Complications: Can migrate and cause delayed injury

  • POCUS has sensitivity near or better than that of combined radiography, PHx, and PE for soft tissue FBs

    • can detect radiolucent objects (organic matter such as wood), including surrounding structures

    • can be used to remove soft tissue FBs

  • Visualization and Findings: FB usually hyperechoic to soft tissue

    • NOTE: bone, scar tissue, and articular surfaces appear hyperechoic

    • Wood and plastic cause shadowing (posterior acoustic shadowing)

    • Metal causes reverberation/comet tail artifacts

    • Determine depth and size with measure function

  • Localization in GI Tract

    • There have been cases where pocus used in the ED to detect ingested FBs

    • Similar process to soft tissue

    • May see some reverberation artifact

  • Hip Ultrasound Notes

    • septic arthritis: spread IVDU, hematogenous, joint surgery, trauma risk factors: age, DM, immunocompromised, prosthetic joint, alcoholics, sepsis, previous injections, * GN will not have high cell count

      • pain +/- fever, limp, bacteria infection, S.aureus

      • DX: gold standard arthrocentesis fluoroscopy

        • Leukocyte count > 50,000 w/ neutrophil predominance, gram stain, culture, microscopic analysis

      • Adult POCUS technique

        • supine pt: with affected leg placed in “ frog leg” positioning

        • curvilinear probe placed inferior to the inguinal ligament, lateral to the femoral vessels and angled 30-40 degrees toward umbilicus

        • scan and fan until you get your image

        • alternatively, can place the probe over the femur and trace it proximally until visualize the femur lost and then angle the probe marker to the longitudinally capture the femur, continuing the rotation until 30-45 towards the umbilicus and the femoral neck and head come into view.

        • >7 cc in adults is pathologic

      • Peds

        • Dxx peds limp: transient synovitis (3-8 years old mostly males, 45-85% effusions) septic arthritis, osteomyelitis, legg-calve, avascular necrosis, fx, muscle strain, juvenile RA, myositis

        • 98% specific in dx hip effusions

        • too much pressure from probe can lead to a false negative. 0-1yr 1-2 cc

        • Peds >4 or >2 difference b/w the two sides.

        • want to measure at femoral neck

        • will appear convexed instead concave.

      • Arthrocentesis

        • ID femoral vessels

        • prepare a sterile field with probe cover

        • anesthetize superficially and deep

        • affix and 18 G spinal needle to 20 cc syringe

        • advance under direct visualization into joint capsule

        • aspirate the appropriate amount of fluid and send analysis

        • use smaller syringe (5CC), keep in syringe and run to lab