。
She let out a scream from the agony.
Literal
She [topic-は] suffering [out of excess of-のあまり] scream [object-を] raised.
The pattern ~のあまり ('out of excess of X') here attaches to 苦しみ ('suffering, agony') — a noun derived from the verb 苦しむ via the masu-stem-as-noun pattern. 叫び声 ('scream-voice') is a compound noun built the same way: 叫ぶ ('to shout') → 叫び (the act of shouting) + 声 ('voice') = 'a scream.' The collocation 叫び声をあげる pairs the noun with あげる ('to raise'), much as English uses 'let out a scream.' The literal Japanese force is 'to raise (one's) scream' — the voice rises out of the body.