Which type of congenital diaphragmatic hernia is most commonly observed?

The most commonly observed type of congenital diaphragmatic hernia is left-sided. This condition typically occurs due to a developmental defect in the diaphragm, which allows abdominal contents, like the stomach and intestines, to move into the thoracic cavity. This defect is more frequently located on the left side for several anatomical and developmental reasons, including the position of the liver which provides more space on the left for herniation.

In most cases, the left-sided hernias are associated with more severe complications, such as pulmonary hypoplasia, due to the effects of the herniated structures on lung development. Therefore, the left-sided hernia is a critical focus in both diagnosis and management in clinical settings.

Other options, such as right-sided or ambilateral hernias, are much less common and do not show the same prevalence in clinical cases. Additionally, a non-specific choice would not provide insight into the prevalence of congenital diaphragmatic hernias, which is specifically addressed by identifying the left-sided versions as the most frequently encountered.