Is a spot of blood that appears after relieving oneself in the lavatory considered menstruation that prohibits prayer and fasting?

The appearance of a spot of blood is not considered menstruation, so it does not prevent prayer or fasting. Sheikh Ibn 'Uthaymeen was asked about a woman who experienced continuous spotting throughout Ramadan (definition) and she fasted. He replied that her fast was valid and that these spots were insignificant because they originated from veins. The general rule is that any discharge after purification, whether it be a brownish discharge, a yellowish discharge, a spot, or a dampness, is not considered menstruation and therefore does not prevent prayer, fasting, or marital intimacy.