Anticoagulants sharply increase hematoma risk after thyroid, parathyroid surgery

Key clinical point: Clopidogrel and anticoagulants are risk factors for hematoma after thyroid or parathyroid surgery.

Major finding: The odds of hematoma were 5.6 times higher with clopidogrel use and 7.5 and 29.5 times higher with oral and injectable anticoagulant use, respectively.

Data source: A retrospective study of 4,514 patients undergoing thyroid or parathyroid surgery.

Disclosures: Dr. Oltmann disclosed that she had no relevant conflicts of interest.




SAN FRANCISCO – Patients undergoing thyroid or parathyroid surgery have a sharply higher risk of postoperative hematoma if they are on clopidogrel or anticoagulants – even if these agents are stopped in advance – researchers reported at the annual clinical congress of the American College of Surgeons.

“Patients with multiple factors considered high risk for postoperative hematoma formation after parathyroid or thyroid surgery should probably undergo a period of observation,” recommended lead investigator Dr. Sarah C. Oltmann, who at the time of the study was the director of endocrine surgery at Parkland Memorial Hospital, University of Texas Southwestern Medical Center, Dallas.

Dr. Sarah Oltmann
Dr. Sarah Oltmann

“The need specifically for anticoagulation in the perioperative period should really be carefully assessed, and decisions regarding their use in the perioperative period need to be made very cautiously,” she added. “This is particularly important when considering the need for an injectable bridge [anticoagulant], and discussions with the patient’s primary care provider or cardiologist should be prompted because obviously a hematoma risk of 11% [seen with injectable anticoagulants] is not insignificant.”

The researchers retrospectively studied 4,514 patients who underwent thyroid or parathyroid surgery at the center between 1994 and 2013. Most of the operations were performed by high-volume surgeons.

Overall, 25% of patients were using an antiplatelet agent and 3% were using an anticoagulant agent, defined in the study as current use or use up to 5-7 days before surgery. “We felt that there may be some alteration of hemostasis both at the time of surgery and in the days following surgery if they were resumed on their home meds,” explained Dr. Oltmann, who is now a clinical instructor of surgery at the University of Wisconsin–Madison.

Overall, 0.5% of patients developed a postoperative hematoma, with the majority of these events occurring in the first 24 hours. Three-fourths of the affected patients had to undergo repeat surgery.

In multivariate analyses, clopidogrel (Plavix) users had 5.6 times the odds of developing a hematoma. But neither lower-dose aspirin (less than 325 mg daily) alone nor higher-dose aspirin alone was associated with this complication.

Hematoma odds were elevated by an even greater extent, 7.5 and 29.5 times, for patients using oral and injectable anticoagulants, respectively. (Subcutaneous heparin was not included among injectable anticoagulants because surgeons at the center seldom use it in this setting, according to Dr. Oltmann.)

Patients also had increased odds of hematoma if they underwent thyroid surgery as compared with parathyroid surgery (odds ratio, 7.9), and had a bilateral procedure as compared with a unilateral one (OR, 4.9).

“Additional studies are needed to better clarify both the risk-benefit ratio of injectable anticoagulation in this patient population and potentially being able to better risk-stratify which patients would be better served with a period of overnight observation,” Dr. Oltmann concluded.

Dr. Raymon H. Grogan
Dr. Raymon H. Grogan

Invited discussant Dr. Raymon H. Grogan, director of the endocrine surgery research program at University of Chicago Medicine, commented, “I think this work represents a level of detail and granularity in regard to anticoagulants that we haven’t seen before in this literature, so it’s really important for us to see these data.

“We tend to get lulled into a false sense of security when we talk about complications related to thyroidectomy because they are so rare. But the truth of the matter is that this is a complication that causes deaths. A recent Nationwide Inpatient Sample study showed that about 1.3% of people who developed a hematoma will actually die in the United States, which is not an insignificant number of people who will die from a complication that’s directly caused by something we’ve done as surgeons,” he said.

Patients often have other risk factors for hematoma, Dr. Grogan noted. Therefore, he wondered, “Who can actually be sent home as a same-day patient after thyroidectomy? … When you combine your … people on these medications, along with all these other risk factors, as well as the risk of significant hypocalcemia postop, it starts to get to the point where, is it really safe to send anyone home the same day after thyroidectomy, given this overwhelming number of different factors that could cause problems?”

“That’s something we all struggle with to a certain degree, trying to be able to best determine who is safe to go home at night and who is not,” Dr. Oltmann replied, noting that risk in the study was greatest for the small proportion of patients on anticoagulants. “So I think a patient who is on some form of anticoagulant, I would definitely have significant reservations about sending home on the same day. They would be somebody I would at least want to keep overnight.”

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