Research: Calculating Observed-to-Expected Total Fetal Lung Volume in CDH Fetuses in Twin Gestation: Is There a Better Way?

Fetal Diagn Ther. 2019 Dec 20:1-9. doi: 10.1159/000504510. [Epub ahead of print] https://www.ncbi.nlm.nih.gov/pubmed/31865353

Calculating Observed-to-Expected Total Fetal Lung Volume in CDH Fetuses in Twin Gestation: Is There a Better Way?

Kim AG1,2Mon RA1Karmakar M1Kreutzman J1,2Ladino-Torres M2,3Treadwell MC2,4Mychaliska GB1,2Perrone EE5,6.

Author information

Abstract

BACKGROUND:

Congenital diaphragmatic hernia (CDH) is a potentially lethal birth defect, and identifying prenatal predictors of outcome is important. Observed-to-expected total fetal lung volume (o/e TFLV) has been shown to be a predictor of severity and useful in risk stratification but is variable due to different TFLV formulas.

OBJECTIVES:

To calculate o/e TFLV for CDH patients part of a twin gestation using the unaffected sibling as an internal control and comparing these values to those calculated using published formulas for TFLV.

METHODS:

Seven twin gestations with one fetus affected by CDH were identified between 2006 and 2017. The lung volume for each twin was calculated using magnetic resonance imaging (MRI), and o/e TFLV was calculated using the unaffected twin’s TFLV. This percentage was then compared to the o/e TFLV calculated using published formulas.

RESULTS:

Lung volumes in the unaffected twins were within normal ranges at the lower end of the spectrum. No single TFLV formula was found to correlate perfectly. Intraclass correlation coefficient estimate was most consistent for o/e TFLV calculated with the Meyers formula and supported by Bland-Altman plots.

CONCLUSIONS:

O/e TFLV measured in CDH/non-CDH twin gestations using the unaffected sibling demonstrated agreement with o/e TFLV calculated using the Meyers formula. We urge the fetal community to standardize the method, use, and interpretation of fetal MRI in the prenatal evaluation of CDH.

© 2019 S. Karger AG, Basel.

KEYWORDS:

Congenital diaphragmatic hernia; Fetal magnetic resonance imaging; Total fetal lung volume; Twin gestationPMID: 31865353 DOI: 10.1159/000504510

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