Pectus excavatum is the most common congenital deformity of the anterior wall of the chest, in which several ribs and the sternum grow abnormally. This produces a caved-in or sunken appearance of the chest. It can either be present at birth or not develop until puberty.
Pectus excavatum is sometimes considered to be cosmetic; however, depending on the severity, it can impair cardiac and respiratory function and cause pain in the chest and back. People with the abnormality may experience negative psychosocial effects, and avoid activities that expose the chest.
Pectus excavatum is sometimes referred to as cobbler’s chest, sunken chest, funnel chest or simply a dent in the chest.
Pectus excavatum is initially suspected from visual examination of the anterior chest. Auscultation of the chest can reveal displaced heart beat and valve prolapse. There can be a heart murmur occurring during systole caused by proximity between the sternum and the pulmonary artery. Lung sounds are usually clear yet diminished due to decreased base lung capacity.
Many scales have been developed to determine the degree of deformity in the chest wall. Most of these are variants on the distance between the sternum and the spine. One such index is the Backer ratio which grades severity of deformity based on the ratio between the diameter of the vertebral body nearest to xiphosternal junction and the distance between the xiphosternal junction and the nearest vertebral body. More recently the Haller index has been used based on CT scan measurements. An index over 3.25 is often defined as severe. The Haller index is the ratio between the horizontal distance of the inside of the ribcage and the shortest distance between the vertebrae and sternum.
Cross sectional scan of a chest with pectus excavatum
Chest x-rays are also useful in the diagnosis. The chest x-ray in pectus excavatum can show an opacity in the right lung area that can be mistaken for an infiltrate (such as that seen with pneumonia). Some studies also suggest that the Haller index can be calculated based on chest x-ray as opposed to CT scanning in individuals who have no limitation in their function.
Pectus excavatum is differentiated from other disorders by a series of elimination of signs and symptoms. Pectus carinatum is excluded by the simple observation of a collapsing of the sternum rather than a protrusion. Kyphoscoliosis is excluded by diagnostic imaging of the spine, where in pectus excavatum the spine usually appears normal in structure.