Sheikh `Abdel Khaliq Hasan Ash-Shareef, states the following: “The ruling in this situation depends on what a female sees, if a lady after intercourse with her husband and after ghusl sees something and she is sure that what she has seen after making sexual intercourse and after performing ghusl is a sperm, then such lady is required to repeat Ghusl. If, however, what she has seen is a normal secretion, then ablution will be sufficient.
I see that it is better to be sure about the secretion seen and then decide accordingly. I also advise couples to wait for just few minutes after sexual intercourse and before performing ghusl to allow all kinds of secretions to appear and then perform ghusl to achieve proper purification.”