IVC: How to measure?

One of the most common questions I receive while teaching at various POCUS courses, either in the US or in Japan, is "Where should we measure the diameter of the inferior vena cava (IVC)?"

Well, there are recommendations from the guidelines, but they are slightly different from one to another. Let us first take a look at this guideline from ASE in 2010.

Rudski LG, Lai WW, Afilalo J, Hua L, Handschumacher MD, Chandrasekaran K, Solomon SD, Louie EK, Schiller NB. Guidelines for the echocardiographic assessment of the right heart in adults: a report from the American Society of Echocardiography endorsed by the European Association of Echocardiography, a registered branch of the European Society of Cardiology, and the Canadian Society of Echocardiography. J Am Soc Echocardiogr. 2010 Jul;23(7):685-713; quiz 786-8.
doi: 10.1016/j.echo.2010.05.010. PubMed PMID: 20620859.

When you read the guideline above, they say (page 692, figure 4) "The diameter (solid line) is measured perpendicular to the long axis of the IVC at end-expiration, just proximal to the junction of the hepatic veins that lie approximately 0.5 to 3.0 cm proximal to the ostium of the right atrium (RA)."

Given above, we could divide the way we measure IVC diameter into four components.

(1) timing of the measurement (2) Axis of the measurement (3) point of the measurement (4) point of the measurement 2

So I guess the article above explains these four points as below:

(1) Timing: End-expiration
(2) Axis: Perpendicular to the long axis of the IVC
(3) Point1: Just proximal to the junction of the hepatic veins
(4) Point2: 0.5 to 3.0 cm proximal to the ostium of the right atrium

Then let us take a look at the next guideline, again from ASE, but in 2015.

Lang RM, Badano LP, Mor-Avi V, Afilalo J, Armstrong A, Ernande L, Flachskampf FA, Foster E, Goldstein SA, Kuznetsova T, Lancellotti P, Muraru D, Picard MH, Rietzschel ER, Rudski L, Spencer KT, Tsang W, Voigt JU. Recommendations for cardiac chamber quantification by echocardiography in adults: an update from the  American Society of Echocardiography and the European Association of Cardiovascular Imaging. J Am Soc Echocardiogr. 2015 Jan;28(1):1-39.e14. doi: 10.1016/j.echo.2014.10.003. PubMed PMID: 25559473.

When you read this article, then the point of measurement is slightly different.

"the diameter of the IVC should be measured in the subcostal view with the patient in the supine position at 1.0 to 2.0 cm from the junction with the right atrium, using the long-axis view."

(4) Point4: 1.0 to 2.0 cm from the junction with the right atrium

Last, not the least, a recent article from again ASE, published this year (note Epub is in 2018).

Mitchell C, Rahko PS, Blauwet LA, Canaday B, Finstuen JA, Foster MC, Horton K, Ogunyankin KO, Palma RA, Velazquez EJ. Guidelines for Performing a Comprehensive  Transthoracic Echocardiographic Examination in Adults: Recommendations from the American Society of Echocardiography. J Am Soc Echocardiogr. 2019 Jan;32(1):1-64. doi: 10.1016/j.echo.2018.06.004. Epub 2018 Oct 1. PubMed PMID: 30282592.

Now, when you read this most recent guideline from the article, the point of the measurement is the same as the guideline in 2015, but the timing is slightly different. 

"The measurement should be made 1 to 2 cm proximal to the junction of the IVC and right atrium. The IVC diameter should be measured at its maximum dimension, usually during expiration."

(1) Timing: should be measured at its maximum dimension, usually during expiration

So, with all these said, I would summarize the guidelines as follows

(1) Timing: measure when it is at its maximum dimension, usually during expiration
(2) Axis: Perpendicular to the long axis of the IVC
(3) Point: 1 to 2 cm proximal to the ostium of the right atrium