Congenital diaphragmatic defects: proposal for a new classification based on observations in 234 patients.

Congenital diaphragmatic defects (CDDs) are a common group of birth defects, yet we presently know little about their pathogenesis. No systematic study documenting the detailed morphology of CDD has been performed, and current classification schemata of diaphragm phenotypes incompletely capture the location and extent of diaphragmatic involvement. To define the range of CDD anatomy, diaphragmatic pathology was reviewed from an examination of 181 autopsy records of children with CDDs at Children's Hospital Boston between 1927 and 2006. Defects were classified according to several parameters, including type (communicating versus noncommunicating) and location (anterior, posterior, etc.). The information permitted development of a phenotyping worksheet for prospective use on patients undergoing diaphragmatic repair at Children's Hospital Boston or MassGeneral Hospital for Children. Fifty-three patients who died between 1990 and 2006 had a total of 63 defects. Thirty-nine had a "classic" CDD phenotype (64% posterolateral, 18% hemidiaphragmatic aplasia, and 18% anterior). The remaining 19 defects, not fitting classical descriptions, were located in the posteromedial, anterolateral, or lateral regions of the diaphragm. Prospective data collected during surgical repair revealed posterolateral defects in 34 of 41 cases that demonstrated wide phenotypic variability in size, location, shape, type, and extent of organ displacement. Congenital diaphragmatic defects display significant phenotypic variation. Because rigorous anatomic evaluation and documentation are important steps towards elucidating the developmental biology of these disorders, we suggest establishment of a new and more precise classification using the model presented herein.