Analysis of APTT Values, Factor VIII Activity, Factor IX Activity, and Clinical Manifestations in Pediatric Hemophilia Patients at RSUD Dr. Soetomo Surabaya Muhammad Sabilal Ma’ruf1, Paulus Budiono Notopuro2,3*, Mia Ratwita Andarsini4,5, Yulia Nadar Indrasari6 Abstract Background: Hemophilia is a blood clotting disorder caused by a deficiency of blood clotting factors,