Precautions Needed to Prevent Hematoma After Thyroid Surgery

CHICAGO — Neck hematomas following thyroid surgery, though rare, are highly associated with key factors including comorbid hypertension and blood pressure changes, underscoring the need for strict precautions in managing patients before and after surgery, new research shows.

“Based on our study, we recommend diligent pre-operative blood pressure control for all patients undergoing thyroid surgery,” said first author Emily Ajit-Roger, of the Faculty of Medicine and Health Sciences, at McGill University, in Montreal, Quebec, Canada, in presenting the findings at the American Thyroid Association 2024 Meeting.

Furthermore, “careful selection of patients for outpatient thyroid surgery is essential,” she added.

Strong consideration is especially needed for “the chronic changes of poorly controlled hypertension that cannot be fixed by immediate, fast-acting antihypertensives that are given in the perioperative setting,” she added.

Research indicates that post-thyroid surgery hematomas occur only at rates of about 0.7%-5.0%, but their positioning in the neck can be highly determinantal, causing potential airway restriction, asphyxiation and death.

While hematomas typically develop within several hours of a surgery, some can take longer, therefore, if a patient is being treated as an outpatient, as is increasingly common, the identification of those at a higher risk for a hematoma has added importance in flagging patients who may possibly require overnight admission.

To better identify such risk factors, Ajit-Roger and her colleagues conducted a retrospective study of all neck hematomas requiring surgical intervention occurring at Jewish General Hospital, McGill University in Montreal, between 2009 and 2024.

Over the study period, they identified 5502 thyroid surgeries, among which 30 (0.55%) hematomas occurred that required a return to the operating room, where all were successfully treated.

The mean hematoma onset time was 2.8 hours post-surgery, with 18 (60%) occurring in the post-anesthesia care unit.

Patients developing hematomas had a mean age of 53.6; 70% were women, and their average body mass index (BMI) was 26.86.

Other characteristics included that 5 (16.7%) were smokers, nearly half (13; 43.3%) had hypertension; four of the patients (13.3%) had type 2 diabetes, and all with diabetes had comorbid hypertension. Four patients (13.3%) had Graves’ disease.

More than half (53.3%) had a central neck dissection, while 40% had a total thyroidectomy. Five patients (16.7%) had prior thyroid surgery, and 8 cases involved unintended parathyroidectomy.

In the preoperative setting, nearly half of patients had systolic blood pressure that was above 160 mmHg (44.8%), in the intraoperative setting, the rate was 31%, and postoperatively, the rate was 34.5%.

Eight (26.7%) of the hematoma cases involved an unintentional parathyroidectomy, including two occurring more than 6 hours after surgery.

Hematomas occurring later, at least 6 hours post-surgery, were associated with a longer hospitalization (P = .024), and with larger nodules, with a mean size of 2.5 cm in hematomas developing in less than 6 hours vs a mean of 2.8 cm among those developing after 6 hours. 

There were also higher rates of total thyroidectomy, central neck dissection, and parathyroidectomy. Ajit-Roger suggests that delayed hematoma presentation may be “associated with larger surgical cavities, potentially masking earlier signs of bleeding.”

Comparisons With Cases Not Developing Hematomas

In a case-control analysis comparing the 30 patients who had postoperative hematomas, with 90 patients who did not develop hematomas after thyroid surgery, there were no differences based on BMI; however, those developing hematomas had higher rates of smoking, hypertension, type II diabetes and prior thyroid surgery.

The study found that total thyroidectomy surgery was associated with a lower postoperative hematoma risk, which surprised the authors. “It’s well established in the literature that total thyroidectomy increases the risk for postoperative hematoma. This makes sense intuitively, the more thyroid tissue is removed, the more vessels could bleed,” said Ajit-Roger.

Compared with those who did not have hematomas, those who did had significantly higher rates of pre-induction blood pressure above 160 mmHg (odds ratio [OR], 3.04) and had higher rates of intraoperative and postoperative episodes of hypertension requiring an antihypertensive. Interestingly, patients with hematoma were more likely to have a non-significant change in blood pressure after the administration of a fast-acting antihypertensive, typically Labetolol (OR, 6.25).

Further, the combination of comorbid hypertension and a postoperative heart rate below 90 bpm showed a strikingly high OR of 26.67 of developing a hematoma.

Speculating on the causes, Ajit-Roger noted that “we know that hypertension causes vascular dysfunction, and a reduced heart rate could indicate an impaired autonomic response, whether it be from a beta blocker or not.”

“[The combination] could potentially compromise the patient’s ability to adequately maintain hemostasis,” she said, noting that further investigation is needed to confirm the theory.

Overall, the findings suggest that “patients with suspected well-controlled hemodynamics and no significant history of hypertension may be better suited for outpatient thyroid surgery,” Ajit-Roger said.

That being said, “at our institution we’re starting to change the practice of stopping ACE [angiotensin-converting-enzyme] inhibitors on the day of surgery unless the surgery is expected to last over 2 hours, which it rarely does,” she noted.

“We also suggest having a discussion with the internist who performed the preoperative risk assessment in order to optimize blood pressure control weeks before surgery.”

The dramatically high odds of developing a hematoma with comorbid hypertension and a low postoperative heart rate below underscore that clinicians should “consider the chronic changes of poorly controlled hypertension that really cannot be fixed by immediate fast-acting per needed antihypertensives that are given in the perioperative setting,” Ajit-Roger added.

Furthermore, patients requiring an extensive thyroid surgery and planned as outpatients “probably should be scheduled among the first cases of the day, considering that a presentation of the hematoma could be delayed.”

Further commenting to Medscape Medical News, senior author Richard Payne, MD, of the Department of Otolaryngology — Head and Neck Surgery, Jewish General Hospital, McGill University, noted that awareness of the increased risk of hematomas with increased blood pressure is “intuitive, but probably not formally understood by many.”

In terms of thyroid cancer, “the surgeries needed to be performed, [but] it is another variable that needs to be accounted for.”

In a comprehensive review of Complications of Thyroid Surgery, published by Medscape’s eMedicine, further recommendations for the prevention of bleeding following thyroid surgery include:

• Avoid traumatizing the thyroid tissue during the procedure
• Provide good intraoperative hemostasis
• Avoid the use of neck dressings, as dressing that covers the wound may mask hematoma formation
• No definitive evidence suggests that drains prevent hematoma or seroma formation

The authors of the study and the eMedscape article had no disclosures to report.