Without stitches, the deep wound would not have closed properly.

stitches 是 stitch 的复数形式。stitch 作为名词本义是"针脚、缝线",在医疗场景中特指医生用来缝合裂口伤口的细线——用针带线穿过伤口两侧的皮肤把裂口合拢,每缝一针留下的一段线就是一条 stitch,若干条连起来就是 stitches。