The Halacha requires reciting the Beracha of "Asher Yasar" after using the bathroom. The Beracha praises Hashem for the orifices of the body which excrete solid and liquid waste which is a critical function for the health of the body. If not for this function, "we could not live even for a short while."
The Halachot Ketanot (1:137) writes that the Hachamim did not institute the Beracha of "Asher Yasar" for a man after marital relations, even though, technically, he did emit seed from an orifice of his body, which is also a wonder of creation. Nevertheless, one should try to use the bathroom after relations, and when he says the "Asher Yasar" after the bathroom, he should have in mind to include the seminal emission in his Beracha.
The Yafeh L’lev (Siman 241:1) points out that Maran in Siman 240 recorded the Halachot of relations and then immediately mentions Halachot concerning urinating. This alludes to the practice of urinating after relations to cleanse the body of any remaining seed. Moreover, Maran is indicating that it is a recommended practice in order to include the act of relations in the Beracha of "Asher Yasar." These Halachot are brought in the new Sefer, Tefila L’David, by Rabbi David Amar a"h, in Halacha 14.
SUMMARY
A man does not recite the Beracha of "Asher Yasar" after marital relations. However, it is recommended that he try to urinate afterwards to include the act of relations in his Beracha of "Asher Yasar" after the bathroom.
