A complication occurred in three of these procedureswhere we combined sclerotherapy with glue or withglue and intravascular laser. All the three complicationswere related to blood coagulopathy with an additionalinfection in two of them. No complications followedthe use of coils or particles.According to the Clavien–Dindo classification, mostcomplications (30 cases, 83.3%) were conservativelymanaged grade I–II (Table 5), of which the most sig-nificant were local skin damage (n1⁄412) and prolongedpain or swelling at the injection site (n1⁄49). We encoun-tered two deeper skin necrosis, which necessitated skingrafts (grade IIIa), and additionally, three grade IV andone grade V complication to be discussed in detail.Figure 2 shows a grade IIIa complication.The four grade IV–V complications involved thethree patients with the most complicated anddiffuse VMs (Figure 3). Moreover, in all thesepatients, the malformation caused severe consumptioncoagulopathy.One paediatric patient (Figure 3, top panel) with anextensive and diffuse retroperitoneal VM, after dorsalneedle puncture of the retroperitoneal lesion, sufferedfrom severe (6 l) intra-abdominal bleeding from the leftphrenic artery. He underwent intravascular emboliza-tion and recovered after treatment in an intensive careunit. The main indication for treatment was consump-tion coagulopathy and DIC which is, after severalsclerotherapy procedures, now under control.The man in Figure 3 (middle panel) had an extre-mely extensive VM of the right leg and lower body,causing hygienic and life quality problems. He hadsevere consumption coagulopathy, a fibrinogen levelclose to zero, and episodes of life-threatening bleedingsand pulmonary embolism. The malformation was con-sidered inoperable because of risk for uncontrollablebleeding. The sclerotherapy-related risk for skindamage and infection was high and was thoroughlydiscussed. Coagulopathy and facilitation for furthersurgery were the main indications for sclerotherapy