An erythropoietin-producing uterine myoma was first reported in 1953 by Thomson and Marson . The prevalence of erythropoietin-producing tumors, which are mainly detected in renal cell carcinoma or hepatocellular carcinoma, is very low in secondary erythrocytosis; the prevalence of erythropoietin-producing uterine myoma is even lower, accounting for only 0.02–0.5% of all uterine myoma cases . There are a few case reports of erythropoietin-producing uterine myoma investigated only from a gynecologic perspective [9, 10]. Polycythemia vera also occurs so rarely that there is currently insufficient evidence to establish a standard anesthetic management strategy. However, a few reports regarding anesthetic management of polycythemia vera can be found [3, 4], suggesting that specific measures are required for this disease. Therefore, we took several steps to prevent arterial and venous thrombosis, in accordance with some of those reports.
Phlebotomy has been used for many years and remains an efficient approach to dilute the concentration of red blood cells with few complications. It was previously reported that the use of phlebotomy to maintain the hemoglobin and hematocrit levels below 16 g/dl and 45%, respectively, reduces polycythemia vera-related complications [11, 12]. We performed phlebotomy in our patient, with a consequent decrease of the hemoglobin level. However, that decrease was insufficient to achieve the target value. With the assumption that hemoglobin and erythropoietin levels would remain low following myoma removal, we chose to proceed with the surgery, rather than repeat phlebotomy. Postponing the surgery would have extended the duration of polycythemia, increasing the risk of complications. Moreover, acute normovolemic hemodilution is helpful in cases that involve the potential for massive bleeding, as it reduces the essential amount of bleeding and avoids the risk of transfusion-related infections. In the present case, we used this method to dilute the concentration of red blood cells. It is ideal to use as thick a catheter as possible for collecting 800 ml of blood effectively without occlusion by thrombus. Although the thickest catheter we could place was 22 G because of the size of the artery, we were able to achieve the target hemoglobin level, as mentioned above.
The administration of low molecular weight or unfractionated heparin is also effective in reducing the risk of arterial and venous thrombosis associated with polycythemia vera, especially during the postoperative period . In addition, anticoagulants including direct oral anticoagulants are recommended for the prevention of postoperative deep vein thrombosis rather than aspirin. In the present case, we administered fondaparinux, a selective inhibitor of factor Xa, instead of heparin. Notably, once daily injection of fondaparinux 2.5 mg has been demonstrated to reduce the relative risk of venous thrombosis in orthopedic surgeries by 50% compared to low molecular weight heparin . In this case, favorable postoperative analgesia was achieved by means of epidural anesthesia. However, from the perspective of thrombosis prevention during the postoperative period, it may be reasonable to perform the ultrasound-guided transversus abdominis plane block and begin using heparin early in the postoperative period without the insertion of an epidural catheter.
Bleeding is reported as a major complication in polycythemia vera . Patients with polycythemia vera can exhibit high platelet counts due to the influence of myeloproliferative disorder; bleeding tends to occur among patients with high platelet count [6, 16]. In contrast, erythropoietin-producing uterine myoma secretes only erythropoietin; therefore, it is not associated with changes in platelet count. Accordingly, our patient’s platelet count remained within the normal range. We also decided to place the epidural catheter into the epidural space for postoperative analgesia. LevGur and Levie suggested the possibility of bleeding in erythropoietin-producing uterine myoma, due to marked consumption of coagulation factors, which led to a deficiency of these factors . This study further supports the use of fondaparinux. Fondaparinux is only associated with factor Xa inhibitory activity, whereas heparin also causes direct inactivation of thrombin. We believe that this characteristic of fondaparinux can lead to a lower incidence of bleeding compared with heparin. Mehta et al. reported 22% reduction in the relative risk of bleeding in the fondaparinux group compared to the unfractionated heparin group . After careful consideration, the epidural catheter was successfully placed and removed without major bleeding, contributing to favorable analgesia.
By using phlebotomy, isovolemic hemodilution, and subcutaneous fondaparinux, successful anesthetic management of a patient with erythropoietin-producing uterine myoma was performed. This successful management suggests the possible application of polycythemia vera-specific therapies to this disease, as well as to the prevention of arterial and venous thrombosis.