The Congenital Pulmonary Airway Malformation
 Volume Ratio (CVR)

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The Congenital Pulmonary Airway Malformation Volume Ratio (previously known as Congenital Cystic Adenomatoid Malformation (CCAM) Volume Ratio)  is a sonographic indicator that has been proposed for the evaluation of fetuses at risk for hydrops and possible intervention. The Congenital Pulmonary Airway Malformation Volume Ratio (CVR) is the volume of the mass normalized for gestational age.

The CPAM volume is estimated using the formula for a prolate ellipse
  •  CPAM volume= (Length X Height X Width  X 0.52 )
The CVR is obtained by dividing  the CAM volume by the head circumference (measured in cm)
  • CVR = (Length X Height X Width  X 0.52 )/Head Circumference

A CVR of <= 1.6 at presentation suggests that the risk of hydrops developing is low in the absence of a dominant large cyst*  Lung lesions with a CVR <1.2 may be followed on a weekly basis. Lesions with a CVR of 1.2 - 1.6  twice per week depending on the gestational age and CVR ratio at initial evaluation

A CVR > 1.6 or a CPAM with a dominant large cyst* increases risk of developing hydrops.  Lesions with a CVR of > 1.6 may be followed 2 to 3 times per week.

*The cyst is dominant if it constitutes greater than a third the size of the CPAM.  These cysts may increase rapidly in size from fluid accumulation.

The calculator below may be used to estimate the CVR.

Enter in centimeters:
Mass Width 

Mass Length

Mass Height
Fetal Head Circumference


Congenital Pulmonary Airway Malformation Volume = cm 3
Congenital Pulmonary Airway Malformation Volume Ratio (CVR) =
cm 2

1. Cass DL, et al. Prenatal diagnosis and outcome of fetal lung masses. J Pediatr Surg. 2011 Feb;46(2):292-8.PMID: 21292076
2. Crombleholme TM, Cystic adenomatoid malformation volume ratio predicts outcome in prenatally diagnosed cystic adenomatoid malformation of the lung.J Pediatr Surg. 2002 Mar;37(3):331-8.
PMID: 11877643
3. Adzick NS, Flake AW, Crombleholme TM. Management of congenital lung lesions. Sem Pediatr Surg. 2003;12:1016.
Di Prima FA, Bet al., Antenatally diagnosed congenital cystic adenomatoid malformations (CCAM): Research Review.
J Prenat Med. 2012 Apr;6(2):22-30.PMID: 22905308

All calculations must be confirmed before use. The suggested results are not a substitute for clinical judgment. Neither nor any other party involved in the preparation or publication of this site shall be liable for any special, consequential, or exemplary damages resulting in whole or part from any user's use of or reliance upon this material.

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