An attached stirge deals 5 (1d4+3) HP of damage at the start of its turn each round. The statblock states:
The stirge can detach itself by spending 5 feet of its movement. It does so after it drains 10 hit points of blood from the target or the target dies.
The monster description later states:
A stirge attacks by landing on a victim, finding a vulnerable spot, and plunging its proboscis into the flesh while using its pincer legs to latch on to the victim. Once the stirge has sated itself, it detaches and flies off to digest its meal.
Assuming rolling for damage rather than just applying average damage, should the damage be capped at exactly 10, at which point the stirge detaches? Or should the full damage from the damage roll that puts the total over 10 still apply?