Ultrasound Reference Values
Bladder – LxWxHx0.75 >100mL = urinary retention
Pregnancy:
Fetal Heart Rate – 120-160 (can be a bit higher in early pregnancies)
Abnormal IUP
Absence of yolk sac if mean sac diameter (MSD) >10mm
Absence of fetal pole (FP) if MSD >18mm
No fetal heart motion if FP >5mm on transvaginal ultrasound
Gestational sac >2cm without yolk sac or fetal pole (Blighted ovum)
When you should see stuff on ultrasound:
Gestational sac @ 4-6 weeks
Yolk sac @ 5-7 weeks
Fetal pole >7 weeks
Ocular – Width >5mm measured 3mm behind globe (think 3.x5 card) = Abnormal
FAST –
0.5 cm stripe at Morrison pouch ~ 500cc of fluid
1 cm stripe at Morrison pouch ~ 1,000cc of fluid
Aorta
>3cm abnormal
>5cm with hypotension = ruptured AAA until proven otherwise
Small Bowel Obstruction
Abnormal bowel diameter = >2.5cm
Abnormal bowel wall thickness = >4mm
Appendix – >6mm + non-compressible = suspicious for appendicits
Pylorus –
Muscle wall thickness >3mm = abnormal
Length >14mm = abnormal
Gallbladder –
Common Bile Duct
>7mm abnormal
>10mm abnormal in pts without GB
Rule of thumb = CBD should be less than the first number of patients age.
Anterior gallbladder wall >4mm abnormal
Liver – Hepatomegaly = >15.5cm in superior-inferior dimension
Spleen –
Normal values –
<12 cm longitudinal
<8 cm transverse
<4 cm thick (deep)
Pancreas
Abnormal size = >3cm in anterior/posterior dimension
Abnormal pancreatic duct size = >2 mm
Pleural effusion –
Maximal distance in supine patient at end-expiration in cranio-caudal dimension
mL of pleural fluid = mm x 20
Pleural thickness <2mm = normal (reference)