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. 
The 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.
- If they are both unsure if they had a complete biyah and they didn't find blood if she didn't feel pain she is tahora. A rabbi should be consulted. 
- There was once a terrible practice for the couple to delay a few days after the wedding to have their first biyah, this is forbidden for several reasons.
- If a couple had pre-marital sex (which is completely forbidden) there's no dam betulim.
The Second Biyah
- If there was blood after the first biyah, even if it was incomplete, and she was tameh, then after the second biyah if there's no blood she's tahora.
- If at the second, third, or later time she sees blood she is tameh as a niddah, even if it is hymenal blood. However, if on the second time she finds nothing she is tahora.
- If after the second biyah there is blood on a colored sheet some poskim are lenient and some are strict.
- If they didn't have a complete biyah the first time and there was no blood, and at the second biyah they did have complete biyah, she is tameh after the second biyah even if they don't find any blood.
- A man shouldn't intentionally try to only accomplish a partial biyah so that she doesn't become forbidden to him.
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. There are only two minor leniencies:
- One, 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. However, if she saw her regular period after she became tameh of dam betulim then she needs to count 5 days from the biyah (and doesn't need to restart the count of 5 days from when her period began). For example, if a couple gets married on Sunday night and she becomes tameh because of dam betulim and then on Tuesday or Wednesday she has her period she needs to wait until Friday afternoon before she can do her hefsek tahara.
- Two, 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 practice of taking a honeymoon immediately after the wedding isn't a proper practice because immediately after the wedding the woman is a niddah and it'll be hard to keep all of the laws of niddah. Additionally, during the niddah days it is forbidden to take a romantic trip with your wife.
Surgical Removal of Hymen
- If a doctor surgically removed the hymen, according to some poskim she is tameh and needs shiva nekiyim, while others are lenient that she is tahora. A rabbi should be consulted.
- If the doctor removed the hymen and then after the first biyah there was no blood, according to some poskim she is tahora and according to others she is a niddah.
- The Rashba (responsa 7:161) writes that even though hymenal blood is blood from a wound since it is only a one time stringency we're strict even about blood from a wound. Furthermore, we're concerned that possibly the first time he didn't do a regular biyah and didn’t break the hymen, so if she sees blood she is tameh. 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. Badei Hashulchan 193:1 explains the Rosh as saying that since the hymen of an adult woman might have dried up if she still sees blood it might not be dam betulim.
- 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. Badei Hashulchan 193:16 quotes the Chachmat Adam who says that even if the man didn't have shichvat zera come out she is nonetheless tameh since the rabbis made the woman tameh after the first biyah as a general rule.
- 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. Badei Hashulchan 193:18 explained the Rama that if he only does haarah it is possible that didn't break the hymen depending on how he went in, but once he does a complete biyah it is very unlikely that he wouldn't break the hymen. 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) and Badei Hashulchan 193:19 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.
- The Badei Hashulchan 193:20 cites the Cheker Halacha who says that if they didn't have a complete biyah she needs to do a bedika in order to be tahora. However, in the Biurim s.v. velo, he adds that it sounds like the other poskim that don't mention this requirement disagree with the Cheker Halacha.
- Badei Hashulchan 193:19 advances several reasons why one could be lenient if they didn't find blood, she didn't feel pain, and they don't know if there was a complete biyah. Firstly, if there was no blood it isn't likely that the hymen broke. Secondly, if there was no pain it is likely that the hymen didn't break. Lastly, the entire tumah of dam betulim is rabbinic and in a case of doubt we can apply the rule of safek derabbanan lkula. He adds that even those who are strict wouldn't be strict if they're not even sure if they had haarah.
- Shach 192:11. The Machasit Hashekel 192:11 explains that among the reasons why it is improper is that he might come to inappropriate thoughts and this might cause bitul zera.
- Batim Lbadim v. 1 p. 632 18:31
- Igrot Moshe YD 1:85, Badei Hashulchan 193:21
- Taharat Habayit v. 1 p. 509, Aruch Hashulchan 193:11, Badei Hashulchan 193. See Aruch Hashulchan who says that she should check the sheets for blood after the second biyah.
- Taharat Habayit v. 1 p. 510 is lenient on a ketem on a colored sheet if it is found after the second biyah unless it is found immediately after the biyah in which case he is strict since there is a possibility that there was a hargasha. Rabbi Willig (Niddah Shiur 113) is lenient even if the ketem is found immediately after the biyah.
- Taharat Habayit v. 1 p. 510 writes that finding a ketem on a sheet immediately after tashmish if she had biya sheniya. He’s machmir for the Sidrei Tahara in combination of the Tzemech Tzedek who says that if she has pain it might be dam betulim. Badei Hashulchan 190:104 is concerned for the Sidrei Tahara that a ketem found immediately after tashmish or the bathroom is potentially deoritta and no kula’s of ketamim apply. Taharat Habayit v. 1 p. 410 writes that he isn’t concerned for the Sidrei Tahara that she had a hargasha and missed it. Taharat Habayit v. 1 p. 204 quotes the opinions of what is meyad. He concludes it is between 15 seconds and 3 minutes.
- Badei Hashulchan 193:21
- Rama 193:1, Badei Hashulchan 193:23
- 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
- Badei Hashulchan 193:27
- 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.
- Badei Hashulchan 193:31
- Badei Hashulchan 193:2 citing Minchat Yitzchak 4:58 is strict while Igrot Moshe YD 87 is lenient. Badei Hashulchan sides with the Minchat Yitzchak. Mishmeret Hatahara 193:6 and Taharat Habayit v. 1 p. 519 are lenient.
- Badei Hashulchan 193:14 quotes the Zera Emet 2:84 who considers her niddah even though she isn't going to see because of the dam betulim since the rabbinic rule was that a woman is tameh after the first biyah in all cases, even where the reasons don't apply. Badei Hashulchan also argues that perhaps she is tahora based on the Maharsha Ketubot 4a. Igrot Moshe YD 1:87 is lenient. Mishmeret Hatahara 193:6 is strict and rejects the proof from the Maharsha who was speaking according to the gemara's din and not the rishonim's chumra.