VENOUS and lymphovenous malformations are congenital, but they may not become clinically apparent until late infancy or early childhood. Venovenous malformations (VVMs) do not regress or involute but rather grow commensurately with the child.1 Rapid enlargement may occur and has been described to develop during puberty, during pregnancy, or with trauma. Here, we report acute and progressive engorgement of a VVM of the face soon after induction of anesthesia, leading to unanticipated difficult intubation.A 22-yr-old, otherwise healthy man with congenital VVM of the right side of the face that was distributed primarily along the second branch of the trigeminal nerve was scheduled to undergo surgical excision with possible reconstruction. His preoperative airway examination revealed a class I airway with greater than 4 cm mouth opening, a full unrestricted range of movement at the neck, and no obvious airway deformity. However, a slight discoloration without associate swelling or deformity on the right upper lip was noted at that time (fig. 1A). The patient was premedicated with 1.5 mg midazolam. After adequate preoxygenation, anesthesia was induced with 200 mg propofol and 100 mg fentanyl, and muscle relaxation was achieved with 10 mg cisatracurium. Immediately after injection of propofol, we noticed that the right side of the face, especially the angle of the mouth, started rapidly swelling (fig. 1B). Closer evaluation revealed that the VVM was rapidly enlarging in size, with significant swelling of the lip and the right side of the cheek. The swelling was particularly evident on the mucosal aspect of the right upper lip and the buccal mucosa. Direct laryngoscopy with a Macintosh size 4 blade was attempted, but despite achieving a view (Cormack II) of the vocal cords, the swelling at the angle of the mouth and right cheek made it impossible to accomplish the intubation at first instance. The trachea was subsequently intubated on the third attempt by retracting the tongue with the flange of the blade way to the left side while simultaneously retracting the right angle of the mouth gently to the right. All along, diligent care was taken to prevent any injury to the VVM. Interestingly, we realized that the enlarged VVM was easy to retract and readily collapsible. Subsequent surgical excision and reconstruction was accomplished uneventfully.Potential complications of vascular malformations, some of which have the potential to be life-threatening, include pain, compression or invasion of adjacent structures, decreased range of motion, bleeding, consumptive coagulopathy, and cosmetic deformity.2 Venous malformations of the face that are associated with obvious anatomic deformity may present significant airway challenge to anesthesia providers.2 In our patient, acute enlargement of the VVM after induction of anesthesia could have placed both ventilation and tracheal intubation in jeopardy. VVM is usually not identified as a risk factor for unanticipated difficult intubation during general anesthesia.3,4 In addition, acute enlargement of facial VVM at induction can also lead to unanticipated difficulty to ventilate the patient with a facemask.5 The cause of acute enlargement of the VVM with induction of general anesthesia in our patient is unclear; however, possible explanations include arteriovenous dilatation secondary to induction of anesthesia or bleeding within the VVM (traumatic or spontaneous). Evaluation of the VVM during surgery did not reveal any evidence of hematoma. Although vascular malformations are relatively uncommon, the dynamic nature of these venous malformations makes general anesthesia particularly hazardous. In our view, awareness of this phenomenon, together with advanced planning, is critical in successfully securing the airway in these patients.