On the first night after a free radial forearm flap transfer to the oral cavity, the flap becomes dark blue and swollen with a brisk capillary refill of under 1 second and a positive Pray test. Pinprick shows dark red bleeding. What is the most likely diagnosis?

• A Arterial thrombosis
• B Venous outflow obstruction ✓
• C Normal postoperative flap appearance
• D Partial flap necrosis

Explanation

Venous congestion produces a dark blue or purple congested flap that is swollen, with rapid brisk capillary refill and dark red blood on pinprick, because blood enters through the patent artery but cannot drain. Arterial insufficiency gives a pale, cool, flat flap with absent or very slow refill and little or no bleeding on pinprick. Venous thrombosis is the commonest cause of early free flap failure and demands immediate exploration.

Reference: Grabb and Smith's Plastic Surgery, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.