Complex sentence: He completed an internship in general surgery at St. Vincent's Hospital and Medical Center, after which he completed his surgical residency in otorhinolaryngology at the New York Eye and Ear Infirmary.
Split into simpler sentences: He completed an internship in general surgery at St. Vincent's Hospital and Medical Center. He then completed his surgical residency in otorhinolaryngology at the New York Eye and Ear Infirmary.