The Night of the Wedding
After the first biyah if a woman sees blood, even if it is hymenal blood, the halacha considers her to be tameh like every other niddah as a concern for regular niddah niddah. Furthermore, if they had a complete biyah and there was no blood she is also tameh. 
After First Biyah
- The halacha is that every virgin whether or not she is bat mitzvah and whether or not she had her period yet, after the first biyah she is a niddah.
- Even if she doesn’t see any blood she is tameh as a niddah.
- It is permitted for the chatan to complete the first biyah even if blood comes out beforehand. It isn’t necessary for him to wait for the ‘ever’ to become limp before coming out, unlike the regular halacha of a woman who becomes a niddah during tashmish.
- If the couple didn’t complete the biyah and she didn’t find any blood, they must consult a rabbi. Some poskim are lenient as long as there wasn’t a complete biyah.
After the First Biyah
- After the first biyah she is tameh as a regular niddah with all of the regular restrictions and need for a hefsek tahara, bedikot, and tevilah.
- The only leniencies are that if she doesn’t see her regular period afterwards she can begin her shiva nekiyim 4 days after the biyah and not 5 according to Ashkenazim who usually wait 5. Additionally, one of the regular harchakot is that the man may not sit on the woman’s bed even when she is not around. For a woman after the first biyah as long as she didn’t have her regular period the man can sit on her bed when she isn’t around.
- The Rashba (responsa 7:161) writes that even though hymenal blood isn't dam niddah since we're concerned that possibly the first time dam niddah came out and he didn’t break the hymen she is tameh and also it is only a one time stringency. Additionally, the Rav Hai Goan (Shaarei Teshuva 168) writes that the dam betulim causes dam niddah to come out as well. The Rashba (Torat Habayit 5b) also implies that dam betulim in it of itself is tahor but rabbinically we’re strict.
- See the Rosh (Niddah 10:1) who writes that the reason for the stringency isn’t because of a concern of dam niddah because we could have attributed it to a wound. Rather it is because we treat all women the same as a mature woman who already saw her period. It isn’t clear why the adult women have a stringency themselves and the blood isn’t attributed to blood from a wound. See the Sidrei Tahara 193:3 who deals with this at length but isn’t satisfied by any answer. Taharat Habayit v. 1 p. 498 explains that the Rosh really to some degree accept the reason of dam niddah getting mixed into the dam betulim. In any event,
- See also the Sefer Eshkol (cited by Taharat Habayit p. 498) who suggests that the reason for dam betulim is because of a concern out of an excitement of the first biyah she might see blood like dam chimud. However, the Lechem Vsimla 193:1 points out that none of the poskim say that there’s a concern of dam betulim for a woman who was already married.
- The Mishna Niddah 64b establishes that according to Bet Hillel a virgin who is younger than the age when it is normal to first get a period and gets married isn't tameh the night of her wedding even if there is blood. Rashi s.v. tinoket explains that we assume that the blood was hymenal blood (dam betulim) she is tahora. If the woman reached the age when it is normal for her to have a period she is only tahor for four nights. Lastly, the mishna concludes, if she already had her period she is only tahor one night.
- The Gemara 65b records the opinion of Rav and Shmuel who hold like the opinion who says that a woman is only tahor for the first biyah and afterwards the husband must abstain from his wife. The gemara adds that Rabbi Yochanan and Reish Lakish agreed with Rav and Shmuel. Rashi explains that Rav and Shmuel were discussing even a woman who didn’t have her period yet. The Rosh Niddah 10:1, Rashba (Torat Habayit 5a), Ran (Shevuot 4b s.v. umistabra), and Raavad (Isurei Biyah 5:24) agree and explain that the halacha for all women is that only the first biyah is muter. However, the Bet Yosef 193:1 explains that the Rambam and Rif understood Rav and Shmuel as only referring to a woman who already saw her period, whether she was a naarah or a bogeret. However, all other women have the same halacha based on the minhag either from the Yerushalmi or the geonim.
- The Rashba (Torat Habayit 5b) writes that even if she doesn’t see any blood we assume that likely there was blood but it was lost or covered by the shichvat zera. The Rosh Niddah 10:1 and Ran (Shevuot 4b s.v. umistabra) agree. Even though the Hagahot Maimoniyot 11:1 quotes the Raavad as being lenient if she doesn’t find any blood, he also cites Rashi, Roke’ach, and Ramban as being strict. Shulchan Aruch 193:1 codifies the opinion of the Rashba.
- Rav Ashi in Gemara Niddah 65b explains that the rabbis permitted him to complete his biyah the first time otherwise there is a concern that he will be afraid of getting involved altogether. This is quoted by the Rosh Niddah 10:1, Rashba (Torat Habayit 5b), and Maggid Mishna 10:7. Shulchan Aruch 193:1 codifies this.
- The Raavad holds that the chatan may only exit after the ever was limp (meyt), however, the Rashba (Torat Habayit 5b) disagrees because dam betulim is only a rabbinic concern and they only imposed it after he comes out. Shulchan Aruch 193:1 accepts the Rashba.
- Rama is lenient if there’s no blood and they only did haarah, which certainly includes the insertion of the crown. The Sidrei Tahara 193:3 discusses how far is included in haarah. Rav Ovadia Yosef in Taharat Habayit v. 1 p. 502 is lenient as long as there wasn’t a complete biyah with the entire ever inside. Rav Mordechai Willig (Niddah Shiur 112) agreed. Shiurei Shevet Halevi 193:7 writes that it is imperative to ask a rabbi as there are those who are lenient and those who are strict about the insertion of half of the ‘ever’ if there’s no blood.
- Rashba (Torat Habayit Hakatzar 5a), Rosh (Niddah 10:2), Rambam (Isurei Biyah 11:8), Tur and Shulchan Aruch 193:1
- Taz 193:4 quoting the Maharal
- Rosh Niddah 10:2 citing the Raavad in explaining Rav Hai Goan, Shulchan Aruch 193:1. See, however, Shivat Tzion 69 who disagrees with Raavad in explaining Rav Hai Goan.