A 58-yeаr-оld mаle presents with а right grоin bulge that he first nоticed 3 months ago. He reports that the bulge becomes more prominent when standing or coughing and decreases when lying down. He describes a dull ache in the area after prolonged standing but denies severe pain, nausea, vomiting, or bowel changes. On physical examination, a soft mass is palpated in the right groin. The mass enlarges with Valsalva maneuver and is reducible when the patient lies supine. When the examiner invaginates the scrotal skin and advances a finger into the inguinal canal, a bulge is felt striking the fingertip during coughing. Which of the following is the most likely diagnosis?