Convert ICD-10-CM K40.90 to ICD-9-CM

ICD-10-CM K40.90 converts directly to:

2015 ICD-9-CM 550.90 Inguinal hernia, without mention of obstruction or gangrene, unilateral or unspecified (not specified as recurrent)

Source: 2020 ICD-10-CM CMS General Equivalence Mappings.