Reference: Sharh ‘Umdatil-Fiqh – Tape No.7, Question No.15
Question: If the menstruating woman completes her menses, but has not had a bath [or shower], is it permissible for her to engage in intercourse with her husband?
Response: No. Do not oppose the command [of Allaah]:
{And do not approach them until they are pure. And when they have purified themselves, then come to them…} – soorah al-Baqarah, aayah 222
[Remember], two conditions must be met before they can engage in intercourse; the flow of blood [from her menses] ceases, and she has then had a bath [or shower].