"Screamed" implies that words might or might not have been used, particularly if "for help" is removed. Screaming is often involuntary. "Shouted" implies that words were included and that the volume and sound were voluntary. Implying that her reaction was involuntary (screamed) suggests that she was heard and rescued purely by chance, not due to her own actions. Frequently women who shout for help are described as "screaming hysterically," which is gendered and leads people to dismiss what women say when they speak loudly or with urgency. Describing a woman as "screaming" is only one step removed. "Shouting" is the more accurate word and the one which probably would have been used if the victim were male.