4 zone protocol, 3 B-lines in one zone = pathologic
2 zones bilaterally is a diffuse B-line pattern

Pericardial effusion
Measure in end-diastole
Size: trivial (seen only in systole), small (<10mm), moderate (10-20mm), or large (>20mm)

Tamponade
Dilated non-compliant IVC is sensitive but not specific
RA systole collapse - 1/3 cardiac cycle = 100% Sn and Sp
RV diastole collapse

LV function
Normal: EPSS <7-10mm, Fractional shortening >25%

RV function
Free wall thickness ≥5mm suggests chronic

IVC
Normal: IVC < 2.1cm and ≥50% collapsible = RAP 3mmHg;
Either abnormal = 5mmHg; both = 8mm Hg

Rules of 4 / Dim Sum Rules
AS severe when Doppler velocity ≥4m/s
LV diameter filling in diastole at least 4cm
LV fractional shortening: 1/4 (25% = normal)
Aortic root size normal <4cm
LA diameter normal ≤4cm
RA diameter normal ~4cm

AAA >3cm, or iliac 1.5cm

IUP = bladder-uterine juxtoposition, myometrial mantle ≥8mm, gestational sac & yolk sac/fetal pole in uterus

Gallbladder
Cholecystitis: Gallstones with ≥3mm thick anterior wall, sonographic Murphy, pericholecystic fluid
Dilated lumen >4cm
Dilated intrahepatic ducts are >2mm and 40% diameter of adjacent portal vein
Dilated CBD≥7mm, more more specific ≥10mm; normal increases with age (first digit of age, starting age 70)

Appendicitis
>6mm, non-compressible, blind ended tubule
Appendicolith (with shadowing), Hyperemia, Local ileus, local FF

SBO
Dilation>25-30mm, back and forth peristalsis, FF/tanga sign, edema (wall >3mm), transition pt

Normal Organ Measurements
Renal: Normal length 9-12cm, width 4-5cm, cortex 1-2cm
Spleen: <13cm craniocaudal
Liver: <13cm midclavicular or <16cm midhepatic

Signs of Pneumonia
Consolidation >1cm specificity approaches 100% for bacterial pneumonia
Sub-centimetre consolidations are common in viral illness and bronchiolitis (non-specific)
Other signs: Focal B-lines, Irregular pleural line, Air bronchograms or fluid bronchograms

Pyloric Stenosis
Abnormal = pi “3.14”
Pyloric muscle thickness 3mm (single, measure hypoechoic only – no hyperechoic mucosa)
Pyloric muscle length 14mm
Antral nipple sign
Target sign in transverse (similar to intussusception)

Mesenteric Adenitis
3 or more lymph nodes in RLQ view ≥5mm

Intussusception
Target sign
Check flow for ischemia
2.5-3cm for ileocolic or colic-colic measured outer wall to outer wall in transverse (Can be smaller in young/premie/small bowel-small bowel intussusception)

EFAST
Check 3 rib spaces in paeds for PTX
Bladder >2cm across = enough for successful cath

Papilledema / Optic Disc Elevation:
0.33mm is 100% Sn, 50% Sp;
0.84mm is 48% Sn, 100% Sp;

Hip effusion
Distance from femoral neck - >5mm total or >2mm difference from contralateral side
Lack of effusion does not r/o septic joint