Factor X (FX) deficiency is a rare autosomal recessive congenital bleeding disorder. The clinical presentation is among the most severe among the rare coagulation defects. Thus, majority of diagnosed patients will receive factor replacement therapy before surgical manipulation. However, the diagnosis of FX deficiency may be overlooked because it is a rare entity. This is a case report of a 15-year-old male patient who was diagnosed with FX deficiency after developing post-operative complications. With regular fresh frozen plasma infusion given, the patient responded well and recovered. However, had he been diagnosed earlier pre-operatively, the post-operative complication could have been prevented. Therefore, pre-operative coagulation screening should be performed in patients with significant bleeding history in both emergency and elective situations to prevent surgical morbidity related to post-operative bleeding.