Ans. c. Immediate fasciotomy (Ref: Rockwood 6/e p2127-2129; Apley 9/e p714, 8/e p728-729)Immediate development of swelling in the arm after contrast injection with numbness and pain is highly suggestive of compartment syndrome due to extravasation of contrast medium. Best treatment is immediate fasciotomy, so that contrast medium and fluid can be drained and patient can be relieved.Extravasation of Contrast and Compartment SyndromeExtravasation of contrast is a possible complication of imaging studies performed with contrast.Most cases of subcutaneous extravasation occur due to small volumes of extravasation of contrast causing pain, minimum swelling and localized erythema, that is rapidly resolved.If larger volumes are extravasated, extensive tissue and skin necrosis may occur. Compartment syndrome is a very rare complication.Acute compartment syndrome occurs when the tissue pressure within a closed muscle compartment exceeds the perfusion pressure and results in nerve and muscle ischemiaQ.It typically occurs subsequent to a traumatic event, most commonly a fractureQ.Clinical Features:Classic features: Pain (bursting sensation), altered sensibility and paresis (or more usually, weakness in muscle contraction).Ischemic muscle is highly sensitive to stretch.If the limb is unduly painful, swollen or tense, the muscles (which may be tender) should be tested by stretching them.Diagnosis:Confirmation of the diagnosis can be made by measuring the intra-compartmental pressure.Treatment:Emergency fasciotomyQ