Is pectus excavatum scary? In a normal person, the thoracic transverse diameter and anteroposterior diameter have a normal ratio. For example, in normal individuals, this ratio of the transverse diameter to the anteroposterior diameter is less than 2.5. However, some children, due to congenital or acquired reasons, may have a sternum that is concave inward in the middle. In such cases, the concavity of the sternum significantly reduces the anteroposterior diameter, and the ratio of the transverse to anteroposterior diameter then becomes greater than 2.5. For pectus excavatum where the ratio is between 2.5 and 3.5, we suggest conservative treatment or observation, and a pectus excavatum suction cup can be used. If the ratio is greater than 3.5, the pectus excavatum is very pronounced, and we recommend surgical treatment. In severe cases of pectus excavatum, where the ratio of the transverse to anteroposterior diameter is greater than 4, there are instances where the chest is almost touching the back, with only a few millimeters of space between the anterior chest wall and the spine during surgery. In such severe cases, the heart is completely pushed to the left side of the patient, significantly affecting both cardiac and pulmonary function, impacting the patient’s physical development. In severe cases, it can also cause significant psychological issues, including severe feelings of inferiority, lack of self-confidence, poor social skills, and even severe depression or suicidal tendencies. Therefore, severe pectus excavatum can indeed be quite frightening.