Guide to Clinical

Ultrasonography in

Emergency Medicine

North Shore/Long Island Jewish

Emergency Medicine

Authors:

Justin Zhao, M.D

Aaron Johnson, M.D

Peer Reviewer: Nicole Li, M.D

Table of Contents

1. Cardiac

2. Pulmonary

3. Abdominal

a. Gallbladder

b. Renal (Bladder, Kidneys)

c. Appendix

d. Bowels

4. Reproductive

a. Female

i. Fetal HR

ii. Gestational age

iii. Ovarian sono

b. Male

i. Testicular sono

5. Vascular

a. Aorta

b. Lower extremity DVT

6. Ocular

7. Trauma: FAST exam

8. Soft tissue

9. MSK

Cardiac Ultrasound

Evaluation for:

1. Pericardial effusions or tamponade

2. Estimates of ejection fraction (i.e. during concern for cardiogenic shock)

3. Evaluation of contractility or wall motion abnormalities (chest pain patient, concern for PE)

Basic anatomy

● 4 different views: parasternal long axis, parasternal short axis, apical four chamber, and subxiphoid

● Right ventricle to left ventricle ratio of 0.6:1 (if RV is larger, think PE, pulmonary hypertension, etc)

● Inferior vena cava should vary in size with respiration, if it does not it is dilated (plethoric)

Pericardial effusion

● Can utilize parasternal long, apical four chamber view or subxiphoid

● Range in size from small (<1cm), moderate (1cm-2cm), to large (>2cm)

● Size of the effusion has less effect on physiology than the speed at which it accumulated

● Acute effusions can lead to tamponade with even very small amounts

Cardiac tamponade

● Occurs when the pressure of the pericardial sac exceed the right ventricular pressure

● First sign is right atrial collapse in systole

● Right ventricular collapse in diastole will follow, visualized as scalloping of the apex in 4 chamber view

● D sign: septum bulges into the LV, making the LV look like the letter "D" on parasternal short

● Mitral inflow variation > 25% during inspiration

Right heart strain using 4 different views

● Parasternal long

○ RV dilation (>2/3 of LV) → ↑ RV size → concerning for strain ○ Plethoric IVC/+sniff test with no variation with inspiration

○ Evaluate for tricuspid regurg

○ Evaluate for clot

○ McConnell’s sign: RV hypokinesis with sparing of the apex in the 4 chamber view

● Parasternal short: interventricular septum bow into left ventricle, aka “D sign”

● Subxiphoid: ⅓ RV and ⅔ LV width of the heart

● Apical: ventricles appear first, compare the ratio of two chambers

● Can use TAPSE for evaluation for prognosis of pulmonary embolism, NOT diagnostic

IVC:

● If the IVC is non-collapsible - needs to consider RH strain

● IVC size: Normal:1.5-2.5 cm

● Dilated IVC is called "plethoric"

● To measure respiratory variation - use M-mode

IVC (cm) Respiratory Changes CVP (cm H2O) Fluid responsive

< 1.5 Total collapse 0-5 Yes

1.5-2.5 >50% collapse 6-10 Yes

1.5-2.5 <50% collapse 11-15 Maybe

>2.5 <50% collapse 16-20 Maybe

>2.5 <50% collapse >20 No

Parasternal Long: Able to visualize aortic & mitral valves & aortic outflow and evaluate systolic function

● Size of aortic outflow (<4cm), LV and LA (<4cm)

● Differentiate between pleural and pericardium effusion

○ Pleural effusion will have anechoic/hypoechoic collection deep to the descending aorta

○ Pericardial effusion will have anechoic/hypoechoic collection between the heart chambers and the

descending thoracic aorta

● EPSS (E point septal separation): the distance between the mitral leaflet to the septal wall

○ <7mm is normal and >10 is reduced ejection function

Parasternal short: evaluate at three levels aortic, mitral, apex level

● Fan the probe to identify the papillary muscles, mitral valve, and aortic valve

● Able to evaluate the contractility at different aspects using SALPI: septal, anterior, lateral, posterior and

inferior

● Aortic level: able to visualize RV, RA, aortic valve, LA, LV

● Mitral level: able to visualize RV, mitral valve

● Apex level: able to visualize RV, LV, papillary muscles

● Good view for RV dilation and hypertrophy

Apical (4 chamber): color doppler

● ventricles appear first, compare the ratio of two chambers

● RV, LV, RA, LA, tricuspid, mitral

● Can use to measure TAPSE (tricuspid annular plane systolic excursion) for R ventricular contractility

● TAPSE < 16mm is concerning for dysfunction and less than <10mm is severe

Subxiphoid view: using liver as an acoustic window to evaluate the heart

● View through the liver → RV → LV

● Great for pericardial effusion, view for FAST exam

● Normal sizing: ⅓ RV and ⅔ LV width of the heart

Pulmonary Ultrasound

Evaluation for:

● Pleural effusions, pulmonary edema, pneumothoraces

Basic anatomy

● Four lung fields per side generally accepted as our standard (see figure 1)

○ Anterior parasternal

○ Lateral

○ RUQ and LUQ views for the bases of the lungs for effusions just superior to the diaphragm

Pulmonary edema / effusions

● A-lines - horizontal air artifact in normal lung parenchyma

○ Pneumothorax can have A -lines

○ A line is a replication of the pleural line and is an artifact

● B-lines - vertical air artifacts lines that go directly downward in the lung space and

represent fluid

○ > 3 B-lines in one intercostal field is pathologic

● Spine sign: able to visualize the spine at the bases due to significant effusion where

the fluid allows sound waves to reach the spine and leaves a white, hyperechoic line

behind the lung field itself

Pneumothorax

● With utilization of M-mode an operator can visualize:

○ Seashore sign which indicates lung motion (negative for pneumothorax)

○ Barcode sign which indicates a lack of lung sliding (therefore a positive

study)

● Lung Point: when moving along different quadrants to find points which have no

lung movement

○ Most sensitive and specific for pneumothorax

● Pleural adhesion and bleb can give false positive for pneumothorax

● Absence of lung sliding can be due to: Atelectasis, ARDS, adhesions, main stem intubation (when

paralyzed), bleb

Abdominal Ultrasound: Gallbladder/Common bile duct Evaluation for: cholelithiasis, cholecystitis, inference of cholangitis, etc

Basic anatomy

● Visualization of the gallbladder (in long & short axis), common bile duct (connect to the gallbladder by the

main lobar fissure), portal vein, inferior vena cava

● Patient starts in a supine position. If having difficulty visualizing, place patient in left lateral decubitus view

and utilize inspiration hold (instruct patient to inhale and hold their breath) in order to improve

visualization

● Curvilinear probe is standard but consider phased array probe to visualize between ribs

Gallbladder

● The gallbladder and portal vein are connected by the main lobar fissure

(MLF), which you can use to find an obscure gallbladder or portal vein if

only one of the two is visible

● Stones visualized within the gallbladder leave posterior shadow

● Gallbladder mimics:

○ Adenomyomatosis: remnants of sinus rokitansky, may look like

polyp but has comet tail artifact

○ Aortic and duodenal bulb: use doppler to identify possible flow

● Acute cholecystitis criteria on ultrasound:

1. Hydropic Gallbladder: >10 cm x 5 cm (width> 5 cm is more

specific)

2. Anterior gallbladder wall thickening > 4 mm (can also be caused by hepatitis, pancreatitis, ascites,

post-prandial pseudothickening, CHF, HIV, malignancy)

a. Measure the anterior wall because the posterior wall is often falsely thicker due to

posterior enhancement artifact

3. Pericholecystic fluid (can also be caused by hepatitis, pancreatitis, ascites)

4. SIN sign: Stone impacted in the neck

5. Gallbladder wall edema

6. Sonographic Murphy's sign

● Wall Echo Shadow (WES) sign: when the

gallbladder is so full of stones - only able to

see the anterior wall and shadow artifact

behind it

○ Can also be seen in "porcelain

gallbladder"

● Balk's 4 reasons for why you can't visualize

the gallbladder:

1. Patient had cholecystectomy

2. Patient just ate, so his gallbladder is

contracted (may also result in

appearance of wall thickening, but

measurement will be normal)

3. GB is full of stones that occupy the

entire lumen, resulting in the WES

sign

4. You're not looking hard enough

CBD (common bile duct)

● normal width is <4 mm, with age adjusted normal: >40 y.o. add 1 mm per decade of life (i.e. 5mm for 50-

59, etc)

● Post cholecystectomy: CBD can be consider normal up to 1 cm

● Mickey Mouse sign: a transverse view of the portal triad, with the portal vein as the head, CBD and proper

hepatic artery as the ears.

a. Put on color Doppler to distinguish the CBD from the blood vessels

Dilated CBD can be due to:

● Choledocholithiasis: Stones can migrate to the common bile duct, causing dilation

● Klatskin tumor (cholangiocarcinoma at the confluence of the right and left hepatic bile ducts)

● Mirizzi: large stone in neck of the gallbladder compressing CBD

● Pancreatic head tumor

● Post-cholecystectomy CBD: can measure up to 1 cm in patients with cholecystectomy

● Age (add 0.1 cm for every decade >40)

● Cholangiocarcinoma

Abdominal Ultrasound: Renal and Bladder Evaluation for: hydronephrosis / hydroureter, renal stones, bladder volume

Basics: visualize the bilateral kidneys and bladder in longitudinal and transverse views. Identify the calyces of the

kidneys and evaluate for hydronephrosis. Normal kidney length 11 +/- 2 cm in the long axis.

Hydronephrosis

● Mild: dilation limited to the renal pelvis

● Moderate: Bear Paw Sign from moderate dilation

of the renal pelvis and major calyces

● Severe: significant compression of the renal

pyramids (essentially appear gone), cortical thinning

Renal cysts

● Vary in size/number, can lead to false positive

FAST exam or misdiagnosis of hydronephrosis

● 50% of people over age 50 can have renal cysts

● Concerning when “complex” ie. septations, internal echoes, not circular

Bladder volume measurements

● Measure the internal diameter of the bladder in vertical/horizontal, then switch to sagittal measure the

width

● On transverse view of the bladder, look for bilateral ureteral jets on color Doppler mode- presence of jets

excludes complete obstruction

Abdominal Ultrasound: Appendix Evaluation for: appendicitis

Basic Anatomy: visualize the appendix, paracolic gutter, cecum, psoas, iliac fossae

Normal Findings

● Outer diameter < 6 mm

● Non-peristalsing tubular structure with closed end

● Located anterior to the psoas, often near the right iliac vessels

Appendicitis Findings

● Non-compressible appendix

● Outer diameter >6 mm

● Appendicolith (look for shadowing)

● Periappendiceal fluid

● Target appearance on the short axis

● Soft Signs: hyperemic or periappy fluid

Tips

In thin patients use the linear probe (it only goes down to 6 cm but has higher frequency and subsequently much

better clarity), if you are able to see the psoas muscle then you know you have enough depth, if not you may have to

use a curvilinear (or just order the CT / MR)

Abdominal Ultrasound: Bowels Evaluation for: small bowel obstruction, large bowel obstruction, diverticulitis

Basics

Reproductive: Fetal Heart Rate Evaluation for: Fetal heart rate (FHR) in setting of recent trauma, sepsis, or other concerning syndrome

Basics: At 20 weeks the fetus is typically near the umbilicus; at 4-6 weeks it is anterior to the bladder. Based upon

estimated weeks vs LMP you will have to adjust the placement of the probe.

Normal Findings

● FHR 110-180, you may have some variation to extremes of this as well

Use of the M-mode and avoidance of b-mode/color doppler

● Doppler may cause harm to first trimester fetuses due to production of thermal energy, so use M-mode

when calculating FHR

● Make sure the depth of the heartbeat waveform is equal to the depth of the heartbeat movement on B-mode

General tips

After you estimate fetal age, try and position the probe in the horizontal axis and scan at the sites where you believe

the fetus will be located. Once you find the fetus you may facilitate the use of the zoom feature to enlarge the chest

and look for movement. Then turn on m-mode and align the reading line over the area of cardiac movement and then

hit the measure button. Freeze the screen and then use the calculate button and select fetal heart rate, and measure

one full complex, you may alternatively measure multiple beats and divide (see below) to try and get an averaged

heart rate.

Reproductive: First trimester pregnancy Evaluation for: New pregnancies

Basics:

At 4-6 weeks the fetus is typically posterior to the bladder. Perform a crown rump length (from the apex of the skull

to the base of the buttocks). CRL has an accuracy of 5 +/- 2 days up to 14 weeks of gestation. Variations can differ

more significantly depending on the degree of spinal flexion that the fetus is displaying.

Normal findings

● Gestational sac +/- double decidual sign

● Gestational sac is the first ultrasonographic sign of pregnancy

● The gestational sac should be surrounded by at least 8 mm of endomyometrium. If less than 8

mm, then suspect an interstitial ectopic pregnancy (located within the uterine wall)

● Yolk sac by 5-6 weeks

● Fetal pole/embryo attached to the yolk sac at 5-6 weeks

● Crown Rump length: These can be correlated with a quantitative beta hCG or LMP depending

upon the situation.

● Cardiac activity- should be visualized when embryo is 6 weeks or Crown Rump Length of 5 mm

Ectopic Pregnancy Ultrasound Criteria:

● Possible- elevated beta and no signs if IUP

● Probable- presence of extrauterine gestational sac containing a yolk sac or embryo, tubal ring,

complex mass, or free fluid

● Definite- presence of extrauterine embryo with cardiac activity

● Ovary looks like a chocolate chip cookie, yolk sac looks like a Cheerio

Reproductive: Testicles Evaluate for: testicular trauma, mass or swelling, pain, inflammation

Basics:

● Use high frequency linear probe 8-10MHz to examine both testicles in long axis and short axis for

comparison

● Use B-mode to identify the testicles and evaluate for fluid collection and/or signs of trauma

● Use Power Doppler to evaluate both arterial and venous blood flow

● Examine the patient in supine, elevate the testicles with gauze/towel, move the penis away from the

testicles

● Sensitivity is low in torsion, evaluate further if pain persists

Normal findings:

● Testicle size 2-3 x 3 x 4-5, homogeneous in appearance

● Most testicles are vertical orientation

● Arterial flow rate approximately .05-.07 m/s

● Venous flow rates .03-.05 m/s

● Go over how to measure the flow rate

Torsion

● Twisting of the testicle on it’s vascular axis/pedicle

● Most reliable sign “whirlpool sign” - defined as an abrupt change in the course of the spermatic cord with a

spiral twist at the external inguinal ring or in the scrotal sac

● Testicular heterogeneity indicates late torsion and testicular nonviability

● The epididymis is usually enlarged

Inflammation

● Orchitis – infection/inflammation of the testicles (eg. Mumps) have increased flow (hyperemic) to the

testicle

● Epididymitis – infection of the epididymis, may mimic torsion, due to hyperemic flow to epididymis

appears to be heterogeneous echogenicity and lobular structure containing radiating hypoechoic bands

Fluid filled

Hydrocele – fluid collection between visceral and parietal tunica vaginalis

Varicocele – dilation of pampiniform plexus veins (99% left sided)

Hematoma

Vascular: Descending Aorta Evaluation for: abdominal aortic aneurysm, descending dissection, undifferentiated abdominal pain age >50

Basics:

● visualize the descending abdominal aorta by measuring aorta in three

locations

○ Proximal: level of celiac trunk (commonly located at the xiphoid)

○ Middle: level of superior mesenteric artery

○ Distal: level of bifurcation of the iliac (just superior to umbilicus)

● Differentiate from IVC via compression and respiratory variation

● Ensure you obtain sagittal views to rule out saccular aneurysms

● Scan the patient in supine position

● Flex the hips and bring the heels to the buttock to dilate the aorta and

improve visualization

Normal Measurements: outer wall to outer wall

● Proximal: Celiac trunk - which branches into the common hepatic and

splenic arteries (also the left gastric artery) producing the "seagull" sign

○ Seagull Sign: right branch common hepatic and left branch

splenic artery

○ Normal size <2.2cm

● Middle: Superior mesenteric artery

○ Pie in the Sky involving the splenic vein, SMA, and left renal

vein

○ Normal size <2.2cm

● Proximal to bifurcation of iliacs

○ Normal size <1.8cm

Abnormal measurements / clinical implications:

● Ectatic aorta 2-3cm

● Aneurysmal >3cm

● Possible surgical intervention at >5cm

Types of aneurysms

● Fusiform (most common, is a uniformly enlarging

aneurysm, circumferential)

● Saccular aneurysm (i.e. outpouching,

asymmetric,classic example is a berry aneurysm)

● Torturous

Signs of aortic rupture:

● Free fluid around aorta

● Elevation psoas (retroperitoneal fluid collection)

● Turbulent flow in aorta

● Break in aorta

Tips:

● Locate the spinal shadow

● Graded compression from the left to minimize and move

bowel gas

● Keep the probe perpendicular to the patient’s abdomen

● Cut off the far field to maximize the information in the

field

Vascular: Deep Vein Thrombosis Evaluation for: clots in the deep venous system of the lower extremities

Basic Anatomy:

● Saphenofemoral junction (figure 1) - even though the saphenous vein is superficial, a clot at the

junction has a high likelihood of embolizing into the common femoral vein

● Common femoral vein - move 1 cm proximal to the SFJ

● Bifurcation of deep and femoral veins (figure 2) - both are considered deep vein

● Popliteal vein & trifurcation into the peroneal vein, anterior tibial vein, & posterior tibial vein

Signs DVT:

● Visualization of clot

● Failure to completely compress the venous walls

● No color on Doppler flow

● Lack of augmentation: suggests clot obstruction distal to the probe

○ Augmentation: use color doppler on the common femoral vein and squeeze the calf for ↑ flow

○ Enlarged lymph nodes can be mistaken for DVTs

● Lack of respiratory variation suggests clot obstruction proximal to the probe

● Lack of augmentation suggests clot obstruction distal to the probe

General tip:

● To improve visualization of leg veins, lift the head of the bed more, or have the patient hang their

leg off the edge of the bed

● If scan is negative for DVT, patient should still get a formal repeat US in 5-7 days

● ED focused 2 point compression DVT study is limited because it doesn't assess for DVTs of the

calf and thigh (DVTs of the thigh are called Focal Segmental)

Figure 1 Figure 2

Ocular Evaluation for: increased intracranial pressure, retinal/vitreous abnormality, trauma

Basic Anatomy:

● From anterior to posterior: anterior chamber → lens → vitreous fluids → retina → optic nerve

● The lens should be hyperechoic

● Vitreous fluids should be homogeneously anechoic

● Optic nerve is linear anechoic structure posterior to the retina

Technique:

● Apply large tegaderm over the closed eyes, remember to use copious

amount of gel

● Use linear high frequency probe with maximal gain to scan the eye gently

with minimal topical pressure

● For each eye, scan in transverse and sagittal then proceed to scan while the

patient is moving his/her eyes up, down, left and right.

Findings

Elevated ICP

● Scan through the eye to visualize the optic nerve sheath diameter

● Measure the width of the

optic nerve 3 mm posterior to

the globe from the inner wall to

inner wall

● Normal diameter < 5mm,

obtain the diameter at its

greatest width

● Dilated optic nerve is concerning for increased intracranial pressure

Retinal detachment vs Vitreous detachment vs vitreous hemorrhage

● Retinal detachment can be seen as a hyperechoic membrane/structure within the vitreous chamber and

typically tethered to optic nerve

● Distinction between retinal and vitreous detachment can be subtle since both can occur simultaneously

○ Retinal detachment tends to be thicker and more hyperechoic and less mobile compare to vitreous

detachment

● Vitreous hemorrhage can be similar to retinal detachment but tends to be less hyperechoic and may have V

shape appearance

Lens dislocation

● Biconvex or round hyperechoic structure behind the anterior chamber is displaced

Intraocular foreign body

● Bright, echogenic entity with associated shadowing or reverberation

Trauma: E-FAST (Extended Focused Assessment with

Sonography for Trauma) Evaluation for: lung and cardiac injuries, free intraperitoneal fluids, i.e liver, spleen, kidneys, and bladder

Basic Anatomy:

● Patient would be supine to be examined at 5 different areas for possible traumatic injury

● Able to detect intraperitoneal fluid volume >200ml

● Any sign of free fluid would be concerning for possible surgical intervention

Locations:

● Hepatorenal space - place curvilinear probe at the anterior axillary line of the right inferior thoracic cage to

visual Morrison pouch and the right kidney

○ Scan thoroughly to evaluate for intraperitoneal free fluid which will be black/hypoechoic stripe

○ Make sure to visual the tip of the liver and the inferior pole of the kidney

○ Scan cephalad to evaluate for the pleural space for possible pleural effusion

● Splenorenal Space - place curvilinear probe at the anterior axillary line of the left inferior thoracic cage to

visualize the spleen and the left kidney

○ Scan for intraperitoneal free fluid around the spleen and the left kidney

○ Note possible splenic or renal hematoma

○ Scan caudally to evaluate the pleural space for possible pleural effusion

● Bladder - place curvilinear probe at the pubic bone and scan caudally for possible free fluid in the anterior

and posterior bladder (refer to abdominal/bladder section for further details)

○ Scan in both longitudinal and transverse plane to fully visualize the whole bladder

○ No need for bladder volume

● Lungs - using high frequency linear probe to evaluate for pneumothorax

○ Place probe at the anterior parasternal and scan down 2 ribs spaces for sign of pneumothorax

(please refer to pulmonary section for further details)

● Cardiac - using phased array probe to visual apical 4 chamber view and subxiphoid view (please refer to

the cardiac section for further details)

○ Evaluate for pericardial effusion and contractility

Musculoskeletal Evaluation for: Fracture, muscular/ligament tear, joint effusion

Location: usually at the point of maximal tenderness and compare with

the contra-lateral limb

Anatomy

● Subcutaneous fat: hypoechoic and thin septations

● Muscle: striated hypoechoic tissue w. Hyperechoic surrounding fascia

● Bones: Hyperechoic w. Posterior shadowing

● Tendons: Denser hyperechoic and narrower striations than muscle

● Cartilage: thin hypoechoic line along the bony cortex

● Bursa: space between tendons and muscles, can be collapsed

● Nerves: hyperechoic and honeycomb appearance in transverse view, located between muscles

● Anisotropy: reduced reflectivity simulates false defect

Rib fractures

Elbow fractures: look for posterior fat pad elevation

Nerve Block Quad tendon rupture

● Contraindication: hepatic failure, allergy, compartment syndrome

● Injection: around the nerve (NOT directly into the nerve)

● Tendon injuries: look for fiber discontinuation, irregularity, or hematoma

Reference:

1. Zhang Z, et al. Ultrasonographic measurement of the respiratory variation in the inferior vena

cava diameter is predictive of fluid responsiveness in critically ill patients: systematic review

and meta-analysis. Ultrasound Med Biol. 2014. May; 40(5):845-53.