What alternatives are available for preoperative Deep Vein Thrombosis (DVT) prophylaxis in a patient with a porcine (pork) allergy undergoing gastric bypass surgery?

From the Guidelines

For preoperative DVT prophylaxis before gastric bypass surgery in a patient with pork allergy, I recommend using direct oral anticoagulants (DOACs) like rivaroxaban (Xarelto) 10 mg daily or apixaban (Eliquis) 2.5 mg twice daily, as they have been shown to reduce major bleeding compared to conventional anticoagulation 1. When considering the options for DVT prophylaxis, it's essential to prioritize the patient's safety and minimize the risk of allergic reactions. Since the patient has a pork allergy, it's crucial to avoid using porcine-derived products.

• Synthetic low molecular weight heparins (LMWHs) like fondaparinux (Arixtra) are a viable option, but the most recent evidence suggests that DOACs may be a better choice due to their reduced risk of major bleeding 1.
• Traditional unfractionated heparin (UFH) at 5000 units subcutaneously every 8-12 hours is another option, as most modern UFH is produced synthetically, but it may not be the best choice given the availability of DOACs.
• Mechanical prophylaxis with sequential compression devices should also be used in conjunction with pharmacological methods to further reduce the risk of DVT. The choice between these options should consider the patient's renal function, bleeding risk, and comorbidities, as well as the most recent evidence available 1.
• It's also important to note that the evidence on major bleeding, all-cause mortality, and VTE-related mortality is uncertain for some of the options, which is why it's essential to prioritize the most recent and highest-quality studies 1.
• In this case, the study by Li et al. (2023) and Wang et al. (2023) provide the most recent and relevant evidence, showing that DOACs probably have a similar effect to conventional anticoagulants in preventing recurrent VTE, DVT, and death, while reducing major bleeding 1.

From the FDA Drug Label

2.2 Deep Vein Thrombosis Prophylaxis Following Abdominal Surgery In patients undergoing abdominal surgery, the recommended dose of fondaparinux sodium injection is 2.5 mg administered by subcutaneous injection once daily after hemostasis has been established. Administer the initial dose no earlier than 6 to 8 hours after surgery.

• Fondaparinux can be used for preoperative DVT prophylaxis before gastric bypass surgery.
• The recommended dose is 2.5 mg administered by subcutaneous injection once daily after hemostasis has been established.
• The initial dose should be administered no earlier than 6 to 8 hours after surgery.
• Since fondaparinux is not derived from pork, it can be used in patients allergic to pork 2.

From the Research

Preoperative DVT Prophylaxis Options

For a patient allergic to pork, the following options can be considered for preoperative DVT prophylaxis before gastric bypass surgery:

• Low molecular weight heparin (LMWH) alternatives, such as fondaparinux, rivaroxaban, and dabigatran, as discussed in 3
• Direct-acting oral anticoagulants (DOACs) like rivaroxaban and apixaban, which have been studied in patients with major gastrointestinal resection or bypass, as reported in 4 and 5

Considerations for Patients with Food Allergies

Patients with a history of food allergies, including those allergic to pork, should be carefully evaluated before undergoing gastric bypass surgery, as the surgery may exacerbate food allergic reactions, as seen in 6

• The disruption of protein digestion from stomach bypass surgery may result in dietary proteins large enough to elicit immune responses being presented to the immune-rich intestinal mucosa
• Additional consideration should be given to patients with a preexisting history of food allergic reactions undergoing RYGB surgery

Bioavailability of DOACs after Gastrointestinal Tract Surgery

The bioavailability of DOACs may be affected by gastrointestinal tract surgery, with rivaroxaban being more affected than apixaban, as reported in 5

• Peak plasma concentrations of rivaroxaban and apixaban were assessed in patients who received these medications after GIT surgery
• The results suggest that surgical resection or bypass of the upper GIT could affect DOAC absorption and subsequently peak plasma concentrations

Gastrointestinal Symptoms after RYGB Surgery

Patients who undergo RYGB surgery may experience increased gastrointestinal symptoms and food intolerance, as reported in 7

• The prevalence of gastrointestinal symptoms and food intolerance was assessed in a large cohort of morbidly obese patients before and after RYGB surgery
• The results show that patients who underwent primary RYGB had increased gastrointestinal symptoms and food intolerance compared to the preoperative state