http://revach.net/article.php?id=2113

Section: Halacha   Category: Tshuvos
Asher Yatzar in Middle of Bedikas Chometz?
The Shulchan Aruch (OC 432:1) paskens that you may not speak between saying the bracha on Bedikas Chometz and starting the bedika. He further says that it is best not speak until you finish the entire bedika. The Mishna Brura says if you talk after the bracha before starting the bedika, you must make another bracha.  However if you already started the bedika and then speak you need not make the bracha again.  You are permitted to speak about things relevant to the bedika and it is not considered a hefsek at all.

What happens if you need to use the bathroom during the bedika, should you say Asher Yatzar right away or should you wait until after the Bedika?  The Piskei Tshuvos (432:1) brings from the Nitei Gavriel (1:14:8) that you should say Asher Yatzar right away especially if your Bedika will continue for a considerable amount of time.  If you wait until the end you may forget to say it then.  Additionally if you need to use the bathroom again before you say Asher Yatzar, you will have lost the first Asher Yatzar since you would only say Asher Yatzar once after the second time.

The Piskei Tshuvos brings a dissenting opinion from the Agudas Aizov of Pupa who writes that you should not say Asher Yatzar until after the bedika is completed.

Important Note: We try to convey the Tshuva to the best of our ability. We admit that our understanding may not be accurate. Please also understand that this Tshuva may not be the final word on this topic. One should consult a Rav before drawing any conclusions.