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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 maximal length of the CPAM in sagittal view is used to measure the length. Perpendicular to this axis at the maximal width of the lesion, the width and height of the CPAM are measured [2]The CVR is obtained by dividing the CPAM 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.
REFERENCES:
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;12:10–16.
4.
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
Design and Javascript created by Mark Curran, MD
, FACOG
All calculations must be confirmed before use. The
estimated results are not a substitute for clinical
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