What is the normal size of the liver in the mid-clavicular line on ultrasound?

Normal Liver Size on Ultrasound in the Mid-Clavicular Line

The normal liver size measured in the mid-clavicular line on ultrasound is approximately 14.0 ± 1.7 cm (range 9.4-21.3 cm), with men averaging 14.5 ± 1.6 cm and women averaging 13.5 ± 1.7 cm. 1

Factors Affecting Liver Size

• The liver size is influenced primarily by body mass index (BMI) and body height, with sex, age, and alcohol consumption (in males) also playing significant roles 1
• Only 11.5% of individuals have a liver size exceeding 16 cm in the mid-clavicular line 1
• There is no significant difference in liver size between males and females in neonates, though this changes as individuals age 2
• Liver size increases progressively from birth through childhood, with accelerated growth in the first year of life 3

Measurement Technique

• A general-purpose curved array abdominal probe with frequency range of 2-5 MHz is typically used for liver measurement 4
• The liver is scanned systematically in real-time through all tissue planes in at least two orthogonal directions 4
• For mid-clavicular line measurement:
  • The probe is placed high in the epigastrium with the indicator in a cephalad orientation 4
  • The probe is swept laterally while being held immediately adjacent to the costal margin 4
  • The liver margin should be maintained within the field of view on the screen 4
  • Asking the patient to take and hold a deep breath often improves visualization 4

Alternative Measurement Approaches

• When the liver margin cannot be visualized below the costal margin, an intercostal approach becomes necessary 4
• For intercostal approach:
  • The transducer is oriented with the plane of the probe parallel to the ribs 4
  • The indicator is directed toward the vertebral end of the rib 4
  • This plane is approximately 45 degrees counter-clockwise from the long axis of the patient's body 4
  • The probe is swept laterally from the sternal border to the midaxillary line until the liver is located 4

Clinical Correlation

• A strong correlation exists between physical examination estimates of liver size and ultrasound measurements 5
• When comparing physical examination findings with ultrasound measurements, a correction factor of approximately 1.6 can be applied to the percussed liver span in the mid-clavicular line to predict the transaxial liver span 5
• In cases where subcostal measurement is difficult due to obesity or excessive bowel gas, midaxillary line measurements can provide an accurate alternative determination of hepatic size 6

Pitfalls and Considerations

• The normal liver is highly variable in size, shape, axis, and location 4
• In some patients, the fundus may extend several centimeters below the costal margin; in others, the liver may be high in the hilum, almost completely surrounded by hepatic parenchyma 4
• To avoid confusing the liver with fluid-filled tubular structures, the entire extent of the organ should be scanned in real time in both long and short axes 4
• A combination of subcostal and intercostal windows allows for views from multiple directions and may help in examining difficult-to-visualize areas 4