Question 4 of 5
(demo test)
Product Demo for BASIC Exam
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A 60-year-old man with a history of atrial fibrillation on anticoagulation underwent 2 stages of Mohs micrographic surgery followed by a ____ repair (shown) for a basal cell carcinoma of the right nasal ala. At his one week follow up visit for suture removal, a small and hard hematoma is palpated at the base of the pedicle. Recent literature suggest ____ anticoagulants as single agents are the most frequently implicated in postoperative bleeding complications in large reconstructions in Mohs micrographic surgery?
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Surgical Dermatology
Basics of Mohs Micrographic Surgery
U
B
The flap shown is a nasolabial interpolation flap. See below for flap classification breakdown. When compared to other single anticoagulant agents, the newer generation oral thrombin inhibitors (rivaroxaban, apixaban, and dabigatran) are more likely to lead to postoperative bleeding complications in dermatologic surgery. Of course, the use of 2 or more anticoagulants is associated with higher bleeding side effects (Eilers et al. Dermatol Surg 2018). See below for review of anticoagulants encountered in dermatologic surgery.
A commonly used flap classification method is dividing them into the 4 categories below:
- Advancement flaps: Utilize laxity adjacent to the wound. An incision is made on either side of the wound and tissue is moved in a linear fashion to cover the defect
- Rotation flaps: Utilize tissue at a distant site, which is then rotated and draped over the wound
- Transposition flaps: Move donor tissue over normal tissue to the site of the defect. All transposition flaps create a secondary defect which requires closure
- Interpolation flaps: Two-stage flaps in which the base of the flap is not immediately adjacent to the recipient site. They can tunnel under or bridge over normal skin
Another classification system for flaps also breaks them down into 4 major categories:
1. Burow’s triangle displacement flaps: (Tissue advancement, requires extensive undermining, depends on skin laxity and tissue elasticity)
- Burow’s flap (Single tangent advancement flap)
- O to T flap (Bilateral single tangent advancement flap)
- A to T flap (Bilateral single tangent advancement flap)
- U flap (Double tangent advancement flap)
- H flap (Bilateral double tangent advancement flap)
- Curvilinear tangent advancement flap (Rotation, Karpandzic, Mustarde)
2. Defect reconfiguration flap: (Island pedicle flaps, tissue advancement depends on pedicle movement, blood supply from pedicle)
- Island pedicle flap (Kite flap, V to Y advancement flap, myocutaneous pedicle flap)
3. Tissue reorientation flaps: (Reorientation of adjacent skin in area of laxity)
- Rhombic transposition flap (Limberg, Dufourmentel, Webster’s)
- Bilobed transposition flap
- Nasolabial transposition flap (Melolabial fold flap)
- Spear’s flap
4. Tissue importation flaps: (Covering large wounds, cover avascular defects, two stages)
- Paramedian forehead flap (Indian flap)
- Nasolabial interpolation flap
- Retroauricular pedicle flap (Pin back flap)
- Modified Hughes flap
- Abbe cross-lip flap
Bleeding complications in dermatologic surgery are low, even with newer generation anticoagulants (rivaroxaban, dabigatran and apixiban) and combination therapy with oral thrombin inhibitors, warfarin, and anti-platelet medications. These medications should be continued to avoid life-changing thrombotic events (Otley et al. May Clin Pro 2003, Kovich et al. JAAD 2003, Chang et al. Dermatol Surg 2015, Eilers et al. Dermatol Surg 2018).
However, in clinical practice where surgery is being planned on a large tumor or where there is an anticipated large and complex reconstruction anticipated in patients on multiple anticoagulants, many surgeons will choose to discuss discontinuing one or more of the anticoagulants in consultation with the patient’s cardiologist prior to surgery. Unless there are extenuating circumstances, consultation with cardiology is not needed, as anticoagulants are generally continued in dermatologic surgery.
The newer generation anticoagulants (rivaroxaban, apixaban, and dabigatran) appear to be much more likely to be associated with hemorrhagic complications in dermatologic surgery than any other single agent (Eilers et al., Dermatolog surg 2018).
In the above cited study of 1800 patients, 1.4% developed a postoperative bleed. The newer generation oral inhibitor anticoagulants (rivaroxaban, apixaban and dabigatran) were 7 times more likely to be associated with one of these bleeding events than the risk from all other single agents combined, with a statistically significant p-value of 0.037.
Prior to this study, the risks of bleeding from aspirin, clopidogrel, and warfarin were studied and reported. One recent study showed that more complex repairs, clopidogrel, and coumadin were all risk factors for increased risks of minor bleeding complications (Bordeaux et al. JAAD 2011). Moreover, they reported that the risks of bleeding were increased by 28 times, 7 times, and 40 times for clopidgrel, coumadin, and combination therapy, respectively, in their study population.
In dermatologic surgery, the evidence is clear. Continue all anticoagulants as prescribed. With coumadin, the desired INR range is typically between 2 and 3. Of note, while many dermatologic surgeons check INR in patients on coumadin to ensure a reasonable level (between 2 and 3) the following studies show no difference in rates of bleeding complications between controls and patients on warfarin with an INR <3.0 (Shalom et al, Am Surg 2008), <3.5 (Alcalay et al. Dermatol Surg 2001), <4.0 (Harbottle et al. Br J Or Max Surg 2014, Sugden et al. Surg 2008), and unspecified INR (Isted et al. J Plast Recon Aesth Surg 2018).
Platelet aggregation and adhesion inhibitors include clopidogrel and aspirin.
Vitamin K antagonist is warfarin.
Many over the counter agents can thin the blood. Some consider fish oils through their omega affects as anticoagulants.
Risks of bleeding complications are highest in the first 48 hours. When encountering a hematoma, the first assessment to be made is whether the bleeding has caused a stable hematoma or an ongoing expanding hematoma.
- Stable hematoma - Non-expanding, small, ecchymotic, firm to fluctuant mass. Typically, no surgical intervention is needed. Observation and warm compresses to hasten the resorption recommended
- Expanding hematoma - Pain is a key sign (typically throbbing). Surgical intervention needed to prevent adverse events
The evolution of a hematoma progresses through 4 phases:
- First stage - Early development: typically occurs within 48 hours, and if not removed then the latter phases occur
- Second stage - Gelatinous phase: hematomas quickly become gelatinous with physiologic clotting. At this point, observation is generally recommended
- Third stage - Organization: At this stage, several days have passed and the clot begins to feel hard and rubbery. These are more difficult to remove. Intervention should be deferred to next phase
- Fourth stage - Liquefaction: After 7-10 days, the organized hematoma begins to liquefy and eventually undergoes resorption. This is the time when one can needle aspirate the liquefaction
Clinical pearl: Identification of closures performed and possible associated complications are important for the BASIC Exam. While you may not be able to identify the specific flap, for the purpose of the BASIC Exam, you should recognize that this is an interpolation flap. As a general rule, anticoagulants are continued in patients undergoing dermatologic surgery. More advanced learners (including those preparing for the CORE & APPLIED Exams) will understand the risks of continuing/discontinuing various anticoagulants, what circumstances justify discontinuation prior to surgery, and which consultants should weigh in prior to doing so.
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