A Case of Factor XIII Deficiency Identified by Recurrent Postoperative Bleeding After Tonsillectomy.

Postoperative bleeding is a well-known complication of tonsillectomy. Although inadequate hemostasis and vascular injury are common causes, occult coagulation disorders may also contribute. Factor XIII deficiency is an extremely rare condition that is particularly difficult to detect preoperatively because PT and APTT typically remain normal. A 27-year-old man underwent bilateral tonsillectomy for a recurrent peritonsillar abscess. Despite normal coagulation screening, the patient developed repeated postoperative hemorrhages requiring surgical management. Further evaluation revealed reduced Factor XIII activity (36%). After Factor XIII concentrate administration, bleeding ceased, and the postoperative course stabilized. Factor XIII deficiency should be considered in patients with recurrent postoperative bleeding despite normal routine coagulation tests. Early recognition and timely replacement therapy may prevent severe complications.