Evaluating risk factors for re-exploration due to postoperative neck hematoma after thyroid surgery: a nested case-control study.

ABSTRACT

PURPOSE: Postoperative bleeding after thyroid surgery remains a potentially lethal complication. Outpatient thyroidectomy is an increasing trend in the high volume centers. There is a need to identify risk factors for postoperative bleeding in order to select proper patients for outpatient thyroidectomy. This study aimed to investigate this issue using a national population-based register. MATERIAL AND METHOD: A nested case-control study on patients registered in the Swedish national register for endocrine surgery (SQRTPA) was performed. Patients with postoperative bleeding were matched 11 by age and gender to controls. Additional information on cases and controls was obtained from attending surgeons using a questionnaire. Risk factors for postoperative bleeding were evaluated with logistic regression and are presented as odds ratios (ORs) with 95% confidence intervals (CIs). The time of bleeding in relation to surgery was also investigated. RESULTS: There were 9494 operations, and 174 (1.8%) of them involved postoperative bleeding. In the whole cohort, patients with postoperative bleeding were older, 58 (46-69) vs. 49 (37-62) years, than patients without, p < 0.01. Male patients had a higher risk of bleeding, OR 2.18 (95% CI 1.58-2.99). In the case-control cohort, drain was an independent risk factor for bleeding, OR 1.64 (1.05-2.57). Two-thirds of patients bled within 6 h after surgery. The incidence of bleeding after 24 h was 10%. CONCLUSION: High age, male gender, and drain are independent risk factors for bleeding after thyroid surgery. Even with careful patient selection, prolonged observation might be necessary in thyroid surgery.