What is the normal diameter of the main portal vein (MPV)?

What is the normal diameter of the main portal vein (MPV)?

• A. 13 mm
• B. 5 mm
• C. 20 mm
• D. 8 mm

Answer: (A)

The main portal vein in a healthy adult normally measures about 1.0 to 1.3 cm in diameter, with the commonly cited upper limit being 13 mm. When performing the exam, you measure the inner luminal diameter on a transverse view near the porta hepatis. A diameter at or approaching 13 mm is considered normal up to that threshold; anything larger suggests portal hypertension or other pathology. A 20 mm measurement would be clearly enlarged, while 5 mm would be smaller than expected for the MPV in an adult, and 8 mm is within normal range but does not reflect the upper normal limit as clearly as 13 mm. Therefore, 13 mm is the best single normal reference.

The main portal vein in a healthy adult normally measures about 1.0 to 1.3 cm in diameter, with the commonly cited upper limit being 13 mm. When performing the exam, you measure the inner luminal diameter on a transverse view near the porta hepatis. A diameter at or approaching 13 mm is considered normal up to that threshold; anything larger suggests portal hypertension or other pathology. A 20 mm measurement would be clearly enlarged, while 5 mm would be smaller than expected for the MPV in an adult, and 8 mm is within normal range but does not reflect the upper normal limit as clearly as 13 mm. Therefore, 13 mm is the best single normal reference.