should be kept in mind that venous obstruction causes microcirculatory thrombosis, platelet trapping, and stasis. Thus, even after successful reanastomosis by leeches, secondary changes in the microcirculation can persist and prevent adequate outflow from being reestablished. 7. Side Effects and Contraindications Modern leech therapy is generally recognized as a relatively safe and well-tolerated treatment modality. A patient who refuses to sign the consent form, refuses prophylactic treatment with antibiotics, or refuses blood transfusion should not be treated with leeches. Although the bite of a leech is felt as a slight pain on the intact skin, this is not relevant in the case of recently reattached digits and flaps, where the skin is anesthetic. Slight localized itching of the Y-shaped bite site (Figure 4) persisting for several hours and up to 3 days is the most common (37.3–75%) adverse effect of leech therapy. Use of 5% potassium permanganate, cold compresses, 10% baking soda paste, Golden Star balm, or Fenistil gel on the affected skin areas can be for more pronounced cases. In severe cases of generalized itching, topical corticosteroids and oral antihistamines should be prescribed. Y-shaped leech bite and the surrounding skin reaction. Signs of regional lymphadenitis, slight swelling, and pain of regional lymph nodes on the side of leech application and subfebrile temperature can occur in 6.4–13.4% of the treated patients and usually appears after 3-4 leech applications. Apparently, such adverse reactions never appear when leeches are applied on oral, nasal, or vaginal mucosa. In very rare cases, allergic skin reactions have been observed. When leeches are applied to the esthetically important areas with thin skin and thin layers of subcutaneous tissue scarring after a leech bite could be a cosmetic problem. In some cases, application to a nearby mucosal surface could avoid these complications [33]. Symbiotic bacteria such as Aeromonas hydrophila and Aeromonas veronii, living in the intestinal tract of the leech, may cause infections in 4–20% of the patients, whose flaps or replanted digits are treated with leeches [40]. Leech-borne Serratia marcescens infections were also reported [24]. Accordingly, prophylactic treatment with antibiotics is necessary. Aeromonas infections can occur acutely (within 24 hours) or in a delayed fashion (up to 26 days) after the beginning of leech therapy. Clinical manifestations of Aeromonas infection vary from a minor wound infection to extensive tissue loss. It is important to stress that leech related Aeromonas infections more frequently develop in very sick and immunosuppressed patients. When applied on intact skin, for example, in patients treated for osteoarthritis, local pain, arterial hypertension, and different forms of spondylosis and dorsopathies, Aeromonas infections are extremely rare. The excess bleeding after leeching can be of concern and transfusions may be needed, especially in patients with a tendency to hemorrhage, who suffer from anemia, or for those taking anticoagulants or platelet-inhibiting drugs. Blood transfusions are given based on a hemoglobin level of <8 g/dL. Usually, 3–6 units of packet blood cells are used to compensate for blood loss. In very rare cases, thrombotic microangiopathy and renal failure have been reported when leeches were applied in patients with arterial insufficiency [33]. Isolated reports describing the appearance of syncopal status or orthostatic hypotension (mainly in older persons with initial