The transverse diameter of the chest on routine radiographs reliably estimates gestational age and weight in premature infants.

BACKGROUND

Prior to digital radiography it was possible for a radiologist to easily estimate the size of a patient on an analog film. Because variable magnification may be applied at the time of processing an image, it is now more difficult to visually estimate an infant's size on the monitor. Since gestational age and weight significantly impact the differential diagnosis of neonatal diseases and determine the expected size of kidneys or appearance of the brain by MRI or US, this information is useful to a pediatric radiologist. Although this information may be present in the electronic medical record, it is frequently not readily available to the pediatric radiologist at the time of image interpretation.

OBJECTIVE

To determine if there was a correlation between gestational age and weight of a premature infant with their transverse chest diameter (rib to rib) on admission chest radiographs.

MATERIALS AND METHODS

This retrospective study was approved by the institutional review board, which waived informed consent. The maximum transverse chest diameter outer rib to outer rib was measured on admission portable chest radiographs of 464 patients admitted to the neonatal intensive care unit (NICU) during the 2010 calendar year. Regression analysis was used to investigate the association between chest diameter and gestational age/birth weight. Quadratic term of chest diameter was used in the regression model.

RESULTS

Chest diameter was statistically significantly associated with both gestational age (P < 0.0001) and birth weight (P < 0.0001).

CONCLUSION

An infant's gestational age and birth weight can be reliably estimated by comparing a simple measurement of the transverse chest diameter on digital chest radiograph with the tables and graphs in our study.