Bedside Ultrasound

Extended Focused assessment with sonography for trauma (E-FAST)

    • Visualize abdominal free fluid (place patient in Trendelenburg to increase sensitivty):
      • LUQ
        • Caudal liver tip / inferior pole of kidney
        • Hepatorenal interface (Morrison's Pouch)
      • RUQ
        • Diaphragm-Spleen interface from 6 to 9 o'clock
        • Splenorenal interface
      • Pelvic
        • Rectovesicular space (behind bladder), recto-uterine pouch (Pouch of Douglas)
      • Tip: Fluid accumulates outside kidney, anechoic within kidney = perinephric fat
    • r/o pericardial effusion
      • Subxiphoid view of heart (Must visualize inferior RV wall and septum to apex to r/o pericardial effusion)
        • RV most anterior
        • Epicardial fat pad anterior (often have echogenicity) vs. pericardial effusion posterior
          • Not related to obesity
        • Pericardial effusion anterior to descending thoracic aorta vs. pleural effusion posterior
        • r/o Tamponade
          • Diastolic RV collapse
          • Systolic RA collapse
          • Fixed IVC
          • *Clinical picture
    • Extended
      • Lung sliding or comet tails to r/o pneumothorax at this area

Advanced Cardiac

  • Assess
    • Pericardial effusion
    • Ejection fraction
    • Right heart strain
  • Consider circle survey (move around in circles) to find better window
  • Parasternal Long-Axis
    • Along sternal border at 3rd-6th ICS (can begin at nipple line), marker right shoulder
      • Ideal for LV ejection fraction, suspect dysfunction if any of the three following:
        • Fractional shortening ([LVIDd-LVIDs]/LVIDd) <30% = LV systolic dysfunction (measured at papillary chordae mid-LV endocardium to endocardium)
        • LV dilation >5.2cm
        • Distance frommitral valve to septum (EPSS) >1cm
      • Effusion posterior to aorta = pleural effusion (anterior = pericardial)
  • Parasternal Short-Axis
    • 3rd-5th ICS , marker to left shoulder
    • Aorta (Mercedez Benz sign) -> Mitral -> Apex
      • Ideal for pericardial effusion, and wall-motion abnormalities
  • Apical four chamber
    • Apex (usually 1-2 ICS below left nipple), marker to right flank and aim beam to right shoulder (may ask patient to lie on left side)
      • Ideal for RV strain
        • RV >2/3 LV consider R heart strain

IVC

  • Long axis IVC
    • Subxiphoid, marker to head
      • Consider assessing "size" at around 1cm for hepatic vein or 2-3cm from RA
        • Consider flat and collapsible (>50% collapsibility with respiration) vs. full and fixed (>2.5cm)
  • Note: No consensus for measurements, sniff test not validated, unlikely helpful for fluid-responsiveness
  • May be useful with cardiac/lung views to differentiate causes of shock
    • PTX = Absent lung sliding / N or ↑ contractility / ↑ IVC
    • Distributive (Sepsis/Anaphylaxis) = ↑ contractility / ↓ IVC
    • MI/CHF = Cardiac contractility / ↑ IVC / B-lines
    • Tamponade = RA/RV collapse, pericardial effusion / ↑ IVC
    • PE = RV strain (RV>LV) / ↑ IVC
      • McConnell's sign: Akinesia of the RV mid free wall but normal motion at the apex

Pelvic

First trimester pain/bleeding (Rule out Ectopic Pregnancy)

  • Rule out shock (vitals), FAST (free fluid)
  • Rule in IUP to rule out ectopic
    • Rare cases 1:10,000 of heterotopic pregnancy
      • Careful in IVF as heterotopic pregnancy can be 1:100
      • Careful in high risk patients (pregnant with IUD/prior tubal surgery)
  • Expect to see IUP
    • Transabdominally bhCG 6500 mIU (6w)
    • Transvaginally bhCG 1500 mIU (5w)
  • Transabdominal
    • Place probe longitudinal above pubic symphysis, identify bladder juxtaposed to uterus, endometrial stripe
  • Transvaginal
    • Endocavitary probe, sterile gel
    • Sagittal plane, identify bladder, then uterus
      • Sweep coronally
  • Interpretation
    • Criteria for IUP (6)
      • Pregnancy criteria (3):
        1. Gestational sac (may have pseudogestational sac in ectopic)
        2. Decidual reaction
        3. Yolk sac or fetal pole with visible fetal heart
      • Intrauterine criteria (2):
        • Bladder-uterine juxtaposition
        • Vaginal-uterine continuity (longitudinal plane only)
      • Safety criteria (1): r/o interstitial (cornual ectopic)
        • Adequate myometrial mantle (can be 5mm or 7mm if you have risk factors)
    • NDIUP (no definitive intrauterine pregnancy) if any of criteria not met
      • r/o ectopic
      • r/o free fluid
      • Note: Gestational sac > 2.5cm or irregular shape without yolk sac/fetal pole is likely nonviable pregnancy
    • Live IUP if FHR >100 (usually expected at 6-7w)

Bladder Volume

  • Height X Length X Depth X Correction coefficient = Bladder volume in mL
    • Correction coefficient:
      • 0.66 for triangular prism
      • 0.81 for ellipsoid
      • 0.89 for cuboid shapes

Small Bowel Obstruction

  • Curvilinear/Linear probe
    • Midline abdomen usually gassy, approach lateral above the pelvis
    • >2.5cm fixed bowel loop, non-collapsible, may have back-and-forth stool movement


Intussusception

  • Pediatric intussusception suspected with target/donut/pseudokidney sign
    • >2.5cm suggests ileocolic intussusception
    • <2.5cm suggests ileoileal intussusception

Gallbladder (r/o cholecystitis)

  • Approaches (subcostal sweep, X-7, posterolateral)
  • Landmark "! sign" (portal vein and main lobar fissure)
  • Optimize image in LL decubitus (differentiate stones/polyps by shifting)
  • Findings of cholecystitis
    • Sonographic Murphy's sign
    • Gallstone (hypoechoic shadowing behind hyperechoic stone)
    • Gallbladder anterior wall thickening >4mm or edema (double wall sign)
      • GB wall thickening can be also due to Ascites, CHF, Nephrotic syndrome, HIV, Renal Failure, Multiple myeloma
    • Pericholecystic fluid
  • Additional findings
    • CBD measurement (inner to inner)
  • Pitfall
    • Misidentification of duodenum

Appendicitis

  • Curvilinear probe
    • Can ask patient to cross right leg over left leg to bring appendicitis closer
    • Start at point of maximal tenderness, look for blind-ended fluid-filled structure
    • Landmark of box to look for appendix
      • Iliac artery (medial)
      • Iliac crest (lateral)
      • Psoas muscle (posterior)
    • Transverse, find ascending colon (gas-filled bumpy), follow gas caudally to cecum where gas shadow ends
      • Longitudinal, and look for fat-stranding, appendix (blind-ending structure with tip), appendicolith (usually at base)
    • Look for iliac artery (appendix may be over), ileum medially
    • Consider switch to linear for more detail
      • Consider more compression, left lateral decubitus
  • Positive ultrasound
    • Non-compressible
    • >6mm (outer-outer wall)
    • No peristalsis
    • Appendicolith
    • Mesenteric fat stranding
    • Surrounding edema/free fluid
    • "Ring of Fire" with Colour Doppler
  • False positive - eg. hydroureter
  • False negative up to 50% of appenticitis cases!

Hip Effusion

  • Linear or curvilinear probe
    • Perpendicular 90 degrees to inguinal folds (longitudinal with femoral head)
    • Compare both sides
      • Hip Effusion if >5mm or >2mm difference between both sides

Testicle

  • Linear probe ("Small parts probe")
  • Patient sitting with good padded support underneath for testicle
  • Place penis fold onto abdomen with towel covering
  • Place probe on testicle
    • Start on normal testicle (adjust brightness and colour gain on normal testicle)
    • Longitudinal plane (probe marker head), and transverse plane
    • Colour flow (or power doppler as direction not important) in testicle and compare to abnormal side
      • Consider squeezing testicle together and can compare both testicles at same time
        • Decreased flow
          • Spermatic cord torsion -> Surgery (and try to manual detorse)
        • Increased flow
          • Testicle - Orchitis
          • Epididymis - Epididymitis (supero-posterior to testicle, scan with marker to head)
        • Irregular heterogenous testicular margins in trauma
          • Ruptured testicle -> Surgery
      • To rule out early testicular torsion, know that venous flow disappears first
        • Spectral Doppler pulse wave (look for arterial AND venous)
    • If normal/increased flow, rescan later (or consult radiology/urology)!
      • Rare cases of intermittent torsion lasting 15 minutes

Ocular Ultrasound

  • Do NOT put globe pressure on eye trauma
    • Use Tegaderm and heaped up gel
  • As usual scan in two planes
  • Use linear probe
  • Stabilize hand on nasal bridge/forehead

Optic nerve sheath diameter (ONSD)

  • Angle probe to ensure lens/iris in transverse plane where optic nerve seems the widest (often slightly lateral and angulating nasally)
    • Measure outside diameter of optic nerve 3mm deep to posterior segment retina
      • In adults (limited data in pediatrics), >5-6mm suggests abnormal ICP (>20mmHg)
        • More accurate with ocular papilledema (optic disc >0.6-1mm)

Vitreous hemorrhage

  • "Snow globe" appearance (blood accumulates on dependent parts of retina), may only see if gain set to very high

Retinal detachment

  • Distinct hyperechoic line always firmly attached to optic nerve sheath
    • As opposed to detached vitreous body loosely adherent (clothes in a dryer) which may not be anchored at the optic nerve sheath, and will move freely with eye movements
    • If macula-on, ie. attached just lateral to optic nerve sheath = OPTHALMOLOGIC emergency (can still save macula)