Ultrasound basics

Abdomen

Gallbladder Wall: <3mm

Gallbladder Size: 4cm transverse

Intrahepatic Bile Duct: <2mm

Common Bile Duct

Normal < 6mm

Intermediate 6-8mm

Abnormal > 8mm

Post cholecystectomy < 10mm

Spleen: <13cm length, <6cm thick

Kidneys: average 11cm (9-13cm)

Liver:

<17cm sagittal length

Diffusely Hyperechoic: Fatty liver, Hemochromatosis, fibrosis

Diffusely Hypoechoic: congestion, acute hepatitis, amyloidosis

Head and Neck

Thyroid Lobes: 4-6cm in length, <2cm in AP or transverse diameter

Thyroid Isthmus: <4mm thick

OB/GYN

Endometrial Stripe

Includes the uterine canal and two layers of endometrium

At the end of menses meaures 2-3mm thick

Proliferative Phase (between the start of menses and ovulation measures) <8mm

Secretory Phase (from ovulation to start of menses) can be 15mm or thicker.

Post menopausal greater than 5mm if bleeding, greater than 11 mm if asymptomatic warrents biopsy

Post menopausal on Tamoxifen should be less than 8 mm

Uterus

Nulliparous: 7x5x3cm

Multiparous: (2-3) 9x6x4

Ovaries:

Premenopausal 18-22 cc

Postmenopausal: depends on age and hormone status but late menopause < 5cc

Ovarian Follicles

Less than 2.5-3 cm

Ovulation occurs when dominant follicle reaches 2.0 cm

Ovarian Cysts

Persistent simple nonfunctioning cyst less than 5 cm is almost always benign but should be followed to confirm stability

If the cyst is more than 5 cm and persists, the likelihood of malignancy increases.

See Also

• Ultrasound artifacts
• Doppler ultrasound