This stitch is used for triangular flaps:

• A. Vertical mattress
• B. Subcuticular running
• C. Half-buried mattress
• D. Buried

Answer: (A)

Triangular flaps benefit from a stitch that both anchors the tissue at the edge and everts the margins so the flap edges sit neatly together. The vertical mattress accomplishes this by taking a deep bite very close to the wound edge on each side, followed by a superficial bite a short distance away on the opposite side, with the knot on the skin surface. This pattern grips the tissue securely, distributes tension along both limbs, and produces slight eversion of the edges, which is exactly what you want when closing a triangular flap where the tip and edges need precise alignment. Other sutures don’t offer the same combination of edge control and tension distribution: subcuticular running stays within the dermis to improve cosmesis but doesn’t manage edge eversion or external tension as effectively; buried or half-buried mattress sutures keep tissue hidden and don’t provide the same surface control for flap edge alignment, making them less suitable for this scenario.