Siman 92
Presented here for study, not as a practical ruling. The Shulchan Aruch rules by Sephardi custom, the Rema's glosses by Ashkenazi custom, and the Kitzur follows Ashkenazi custom. For a practical question, ask your rabbi.
א הָיָה צָרִיךְ לִנְקָבָיו, אַל יִתְפַּלֵּל. וְאִם הִתְפַּלֵּל, תְּפִלָּתוֹ תּוֹעֵבָה, וְצָרִיךְ לַחֲזֹר וּלְהִתְפַּלֵּל. וְהָנֵי מִילֵי שֶׁאֵינוֹ יָכוֹל לְהַעֲמִיד עַצְמוֹ שִׁעוּר הִלּוּךְ פַּרְסָה, אֲבָל אִם יָכוֹל לְהַעֲמִיד עַצְמוֹ שִׁעוּר פַּרְסָה, יָצָא בְּדִיעֲבַד. אֲבָל לְכַתְּחִלָּה לֹא יִתְפַּלֵּל, עַד שֶׁיִּבְדֹּק עַצְמוֹ תְּחִלָּה יָפֶה: הַגָּה: וְכָל הַנִּצְרָךְ לִנְקָבָיו אָסוּר אֲפִלּוּ בְּדִבְרֵי תּוֹרָה, כָּל זְמַן שֶׁגּוּפוֹ מְשֻׁקָּץ מִן הַנְּקָבִים (הַגָּהוֹת מַיְמוֹנִי פֶּרֶק ד' מֵהִלְכוֹת תְּפִלָּה).
1 One who Needs to Relieve Themselves and the Laws of Washing for Prayer, and Other Preparations for Prayer - containing 10 s'ifim. One who needs to relieve themselves should not pray, and if they prayed, their prayer is an abomination and they need to go back and pray again. And these things said are [regarding the case] of one who is not able to hold themselves back [without using the toilet] for the amount of time it takes to walk a parasang, but if one is able to hold themselves back for the amount of time of a parasang [and prays], they have fulfilled their obligation [to pray the Amidah] after the fact. But from the outset, one should not pray until they have checked themselves well beforehand. Rema: And anyone who needs to relieve themselves is forbidden even from [engaging in] matters of Torah as long as their body is filthy from their waste. (Hagahot Maimoni, Chapter 4 on the Laws of Prayer)
ב אִם בְּאֶמְצַע תְּפִלָּתוֹ נִתְעוֹרֵר לוֹ תַּאֲוָה, יַעֲמִיד עַצְמוֹ עַד שֶׁיִּגְמֹר, וְלֹא יַפְסִיק. וְאִם בִּשְׁעַת קְרִיאַת שְׁמַע וּבִרְכוֹתֶיהָ נִתְעוֹרֵר בֵּין לִקְטַנִּים בֵּין לִגְדוֹלִים, קוֹרֵא כְּדַרְכּוֹ: הַגָּה: וְדַוְקָא שֶׁאֵינוֹ מִתְאַוֶּה כָּל כָּךְ דְּאִית בֵּיהּ מִשּׁוּם בַּל תְּשַׁקְּצוּ, אֲבָל בְּלָאו הָכֵי יוֹתֵר טוֹב לְהַפְסִיק (תְּשׁוּבַת הָרַשְׁבָּ"א סִימָן קל"א פָּסַק דְּמֻתָּר וּתְרוּמַת הַדֶּשֶׁן סִימָן ט"ז פָּסַק דְּאָסוּר וְצָרִיךְ לְחַלֵּק כֵּן) וְאִם רָצָה לְהַרְחִיק וּלְהָטִיל מַיִם, עוֹשֶׂה.
2 If, while in the middle of one's prayer [i.e. Amidah], he feels an urge [to relieve himself], he should maintain himself [in prayer] until he has finished, and not interrupt. And if at the time of the Recitation of the Sh'ma and its blessings he feels an urge, regardless of whether it is for urinating or defecating, he may read it normally. Rema: And [this is] specifically if one does not feel so much of a urge that there is an element of "Do not cause an abomination" (Leviticus 20:25). But if this is not so, it is better to interrupt [one's prayer and use the toilet] (Responsum of the Rashb"a, section 131, who ruled that it is permissible, and the Terumat haDeshen section 16, who ruled that it is prohibited. And one needs to distinguish such [i.e. between those sources]) And if one wanted to distance himself and urinate [during the Recitation of the Sh'ma and its blessings], he may.
ג צָרִיךְ קֹדֶם תְּפִלָּה לְהָסִיר כִּיחוֹ וְנִיעוֹ וְכָל דָּבָר הַטּוֹרְדוֹ.
3 One needs, before the prayer [i.e. the Amidah], to rid himself of his mucus and phlegm and anything which [might] distract him.
ד צָרִיךְ לִרְחֹץ יָדָיו בְּמַיִם, אִם יֵשׁ לוֹ. וְאִם אֵין לוֹ, צָרִיךְ לַחֲזֹר אַחֲרֵיהֶם עַד פַּרְסָה, וְהָנֵי מִלֵּי כְּשֶׁהוּא הוֹלֵךְ בַּדֶּרֶךְ וְהַמַּיִם נִמְצָאִים לְפָנָיו, אֲבָל אִם צָרִיךְ לַחֲזֹר לַאֲחוֹרָיו לִמְקוֹם מַיִם עַד מִיל, חוֹזֵר. יוֹתֵר מִמִּיל אֵינוֹ חוֹזֵר, וְאִם מִתְיָרֵא שֶׁיַּעֲבֹר זְמַן הַתְּפִלָּה, יְנַקֶּה יָדָיו בִּצְרוֹר אוֹ בְּעָפָר אוֹ בְּכָל מִדֵּי דִּמְנַקֵּי וְעַיֵּן לְקַמָּן סִימָן רל"ג.
4 One needs to wash one's hands with water if he has [it]. If one does not have [water], he needs to travel up until [the distance of] one parasang [to find it]. And this is specifically when one is traveling on the road and water is found ahead of him. But if he needs to travel backwards to the location of the water, he [only] needs to travel up to a mil; [but] more than a mil, he does not [need to] go back. And if one is worried about missing the time of prayer, he should clean his hands on a rock or in dirt or in any cleaning substance [and see below, Orach Chayyim 233]
ה רָחַץ יָדָיו שַׁחֲרִית וְהִסִיחַ דַּעְתּוֹ, צְרִיכִים נְטִילָה לִתְפִלָּה. אִם יֵשׁ לוֹ מַיִם, אַף עַל פִּי שֶׁאֵינוֹ יוֹדֵעַ לָהֶם שׁוּם לִכְלוּךְ, וְלֹא יְבָרֵךְ. וְאִם אֵין לוֹ מַיִם מְזֻמָּנִים, אֵינוֹ צָרִיךְ לַחֲזֹר וְלִטֹּל: הַגָּה: וַאֲפִלּוּ הָיָה יָדָיו מְלֻכְלָכוֹת וְנוֹטְלָן לִתְפִלָּה, אֵינוֹ מְבָרֵךְ וּכְדִלְעֵיל סִימָן ז'.
5 If one washed his hands in the morning, and he got distracted, they need a [re-]washing for prayer if he has water, even if one does not know whether they [i.e. his hands] have any dirt [on them], and he should not bless [for the washing of their hands]. And if he does not have readily available water, he do not need to go back and wash. Rema: And even if his hands were dirty and he washes them for prayer, he should not bless - and see above Orach Chayyim 6
ו הָעוֹמֵד בִּתְפִלָּה, וְנִזְכַּר שֶׁנָּגַע בְּמָקוֹם מְטֻנָּף, דַּי בְּנִקְיוֹן עָפָר אוֹ צְרוֹרוֹת, אוֹ מְחַכֵּךְ יָדָיו בַּכֹּתֶל.
6 One who is standing in prayer [i.e. the Amidah] and recalls that he touched a dirty place, it suffices for cleansing [to use] dirt or rocks or rub his hands on a wall.
ז מָקוֹם מְטֻנָּף, הַיְנוּ מְקוֹמוֹת הַמְכֻסִין בְּאָדָם לְפִי שֶׁיֵּשׁ בָּהֶם מִלְמוּלֵי זֵעָה וְכֵן אִם חִכֵּךְ הָרֹאשׁ: הַגָּה: וְלָכֵן אָסוּר לִגֹּעַ בִּמְקוֹמוֹת אֵלּוּ בְּשָׁעָה שֶׁעוֹמְדִים בִּתְפִלָּה אוֹ עוֹסֵק בַּתּוֹרָה (כָּל בּוֹ) וְכֵן בְּצוֹאַת הָאֹזֶן וְהָאַף כִּי אִם עַל יְדֵי בֶּגֶד (מַהֲרִי"ל):
7 A dirty place is [referring to] places that are [normally] covered on a person['s body] because they have beads of sweat on them, and similarly with scratching the head. Rema: And therefore it is forbidden to touch these places at the time that one stands in prayer [i.e. the Amidah] or is engaged with the Torah (Kol Bo). And similarly with discharge of the ear [wax] and nose [mucus] except by means of a cloth (Maharil)
ח הַמַּשְׁתִּין לֹא יִתְפַּלֵּל עַד שֶׁיִּשְׁהֶא כְּדֵי הִלּוּךְ ד' אַמּוֹת מִשּׁוּם נִצּוֹצוֹת וְהַמִּתְפַּלֵּל לֹא יַשְׁתִּין עַד שֶׁיִּשְׁהֶא כְּדֵי הִלּוּךְ ד' אַמּוֹת שֶׁכָּל ד' אַמּוֹת תְּפִלָּתוֹ שְׁגוּרָה בְּפִיו וְרָחוּשֵׁי מְרַחֲשִׁין שִׂפְוָתֵיהּ.
8 One who urinates should not pray until enough time has elapsed [between ending urination and beginning prayer] to walk four cubits, because of [lingering] drops [of urine]. And one who prayed [already] should not urinate until enough time has elapsed to walk four cubits, since for the entire 4 cubits, one's prayer still flows in one's mouth and one's lips are still moving.
ט הָרוֹקֵק לֹא יִתְפַּלֵּל עַד שֶׁיִּשְׁהֶא ד' אַמּוֹת. הַמִּתְפַּלֵּל לֹא יִרֹק עַד שֶׁיִּשְׁהֶא ד' אַמּוֹת וְדַוְקָא לִרְצוֹנוֹ אֲבָל אִם נִזְדַּמֵּן לוֹ רֹק מֻתָּר ע"ל סי' צ"ז.
9 One who spits should not pray until enough time has elapsed [between ending spitting and beginning prayer] to walk four cubits. One who prayed [already] should not spit until enough time has elapsed to walk four cubits. And [this is] specifically [when one spits] on purpose, but if spittle happens to come forth on it's own, it is permitted. [See Orach Chayyim 97]
י טוֹב לִתֵּן צְדָקָה קֹדֶם תְּפִלָּה:
10 It is good to give tzedakah (donate to charity) before prayer.