9 days later, she was passing large, golf ball sized clots; experienced abnormal vaginal bleeding that got heavier and heavier/ She did report spotting after biopsy in office; Ultrasound showed thickened endometrium; During ultrasound, they saw thickening, and discussed complex hyperplasia; hemoglobin 8/ 5; With the first dose, she had her period a week previously so knew it wasn't time for one; She is frustrated; HCPs think maybe the type of vaccine (mRNA) led her to possibly have early diagnosis of uterine cancer; she lost so much blood had to have transfusion/ been bleeding consistently except for one week; With the first dose, she had her period a week previously so knew it wasn't time for one/ It was heavy for the first 7 days, wouldn't stop, then got heavier; This is a spontaneous report from a contactable consumer, the patient. This case is for bnt162b2 first dose. A 78-years-old female patient received bnt162b2 (PFIZER-BIONTECH COVID-19 VACCINE, solution for injection), dose 1 via an unspecified route of administration, administered in arm right on 10Jul2021 (age at vaccination: 78-years-old) (Batch/Lot Number: EW0181) as DOSE 1, SINGLE for covid-19 immunization. Medical history included covid-19 from Oct2020 to an unknown date (she had the Covid 19 virus in Oct2020). Concomitant medication included cyanocobalamin (VITAMIN B12) taken for an unspecified indication, start and stop date were not reported (She was taking vitamin B12 up until this occurred). History of all previous immunization with the Pfizer vaccine considered as suspect (or patient age at first and subsequent immunizations if dates of birth or immunizations are not available): Vaccine Name was none. Additional Vaccines Administered on Same Date of the Pfizer Suspect If applicable, list all vaccines administered on same date with the Pfizer vaccine considered as suspect: Vaccine Name was none. Prior Vaccinations (within 4 weeks) If applicable, list any other vaccinations within four weeks prior to the first administration date of the suspect vaccines: Vaccine Name was none. Historical vaccine included previously received Rubella vaccine for immunization on an unknown date (age at vaccination: 18-years-old) and experienced Encephalitis and severe headaches. On 10Jul2021, patient experienced abnormal vaginal bleeding that got heavier and heavier, on 18Jul2021, patient experienced hemoglobin 8/ 5, thickened endometrium and hyperplasia, on 19Jul2021, patient experienced she was passing large, golf ball sized clots, and on an unknown date in 2021, patient experienced rest of the events. It was reported a few hours after that dose (first), she experienced abnormal vaginal bleeding that got heavier and heavier. 9 days later, she was passing large, golf ball sized clots. She saw her OBGYN and went to the ER twice. Was admitted to the hospital and given 2 units of blood for a hemoglobin of 5. Never stopped until her second ER visit on 22Jul2021, was she was given Provara. She then had no bleeding until 06Aug2021, when she got her second dose. Her OBGYN told her she should be fine because she was on Provara and that should keep her from bleeding. Ultrasound showed thickened endometrium. HCPs think maybe the type of vaccine (mRNA) led her to possibly have early diagnosis of uterine cancer. They were talking about doing a D&C and possible a hysterectomy. Before jumping into severe response, she wanted to know if there was a link or other reports. Product verified with patient, reported that the last time she experienced this type of bleeding was after having kids, who were then 27, 22, and 13 years old, as in during the first couple of weeks after, you pass clots, then it gets lighter. Her periods did not normally have clots or anything she can feel, and typically last about 7 days. She had Covid in October, and after, missed periods every other month, but thought maybe it was early menopause. With the first dose, she had her period a week previously so knew it wasn't time for one. It was heavy for the first 7 days, wouldn't stop, then got heavier. She reported that she lost so much blood had to have transfusion. She wasn't on hormones or because prior to that, her husband had vasectomy so she didn't need to. During ultrasound, they saw thickening, and discussed complex hyperplasia. During her hospital stay, they stopped bleeding with 4 pills of Provera. On the 2nd day of taking it, the bleeding lightened up with no clots; by the 3rd day, there was no blood at all, and that lasted for almost 2 weeks. She did report spotting after biopsy in office. Then, when she got her second dose on that Friday, within 2 hours, she was back to heavy bleeding. In the last 48 hours, she started passing blood clots again. Provera was not stopping it this time (generic version). They were wanting to D&C and hysterectomy and check for uterine cancer. She was asking, was abnormal bleeding linked, she knew it didn't give her cancer. She was frustrated because she was on an hour long phone call with her doctor's office and they basically told her she was crazy, she looked up and saw other reported of women having abnormal bleeding. She did not think she was crazy, that it was too high of a coincidence, and that never did she have to have a transfusion for a period. She got the first dose of the Covid 19 vaccine on 10Jul2021 and a few hours after she started having abnormal vaginal bleeding. She thought maybe the Covid 19 vaccine kick started her period. The bleeding got heavier and heavier towards day 7. On day 8 or 9 after the vaccine she passed big, large blood clots, golf ball sized blood clots, she could feel them leaving her body. She went to the emergency department on 18Jul2021 and her hemoglobin was an 8. The emergency department didn't do anything, she was sent home to follow up with her OB/GYN. Before her appointment with her OB/GYN which was 3 days later, she had to go back to the emergency department by ambulance and her hemoglobin was 5. While at the hospital she received 2 units of blood. She was prescribed birth control. She hasn't been on birth control in 13 years. She has normal periods, not light but not heavy. She hasn't had any issues in 13 years. She said the bleeding after having children wasn't even as bad as the bleeding she was having now. She was prescribed Provera and it slowed down the bleeding and did stop the bleeding for a week. Then on last Friday, 06Aug2021, she got her second Covid 19 vaccine. Friday night she started bleeding heavily even though she was on the Provera. She's still bleeding now after the second Covid 19 vaccine. Her OB/GYN told her she should be fine to get the second Covid 19 vaccine because she was taking the Provera. Her doctor told her she had a thickened endometrium on ultrasound and biopsy. Her doctor thought she might have uterine cancer. She did not want a misdiagnosis. What if the mRNA changed her cells. She thought she was having a normal response to this but her doctor thought she was crazy. Lab test was abnormal. But since receiving the first Covid 19 vaccine she has been bleeding consistently except for one week. She reported she had 3 vaginal births. She had different birth control that she had taken in the past prior to the Covid 19 virus and Covid 19 vaccines. After her last daughter was born 13 years ago, she had not taken any birth control because her husband had a vasectomy. She did not have a history of bleeding disorders. She was taking vitamin B12 up until this occurred. She was having normal pap smears before this. She's thinking she may have had an immune response to the Covid 19 vaccine. Her doctor suggested that the Covid 19 vaccine identified possible uterine cancer sooner rather than later and that doesn't even make sense to her. How would the Covid 19 vaccine cause her to shed blood in clots because she doesn't know. The last time she had big blood clots like this were after her daughters were born especially the last one 13 years ago. The second time she went to the emergency room was on 22Jul2021 and she went by ambulance to (name) in (place). She was seen by an OB/GYN there. She had another ultrasound done, blood work, and her hemoglobin was 5 so her blood was cross matched and she received 2 units of blood. She was admitted to the observation unit because the blood took 6 hours and she didn't even have her own room because of the hospital's capacity. She was discharged the next day on 23Jul2021. Her hemoglobin after the 2 units of blood went to 8.5. The doctor didn't want to keep her in the hospital because of all the Covid 19 virus patients. When probing for adverse events following vaccine she reports she thought when she was 18 years old, 30 years ago she had a Rubella shot. She did not think it was the whole MMR vaccine. She got encephalitis after the Rubella vaccine. She had severe headaches for 3 weeks. The doctor thought it was related to the Rubella vaccine. She had to get the Rubella vaccine because in California, vaccines are required prior to marriage to check for immunity. The event vaginal bleeding resulted in emergency room and physician office visit. Therapeutic measures were taken as a result of the events 9 days later, she was passing large, golf ball sized clots, vaginal bleeding, bleeding and heavy periods. The patient was admitted to hospital for overnight for the events 9 days later, she was passing large, golf ball sized clots and vaginal bleeding on an unknown date in 2021. The outcome of the event vaginal bleeding was not recovered, whereas of rest of the events was unknown.  This follow-up is being submitted to notify that the lot/batch number is not available despite the follow-up attempts made. Follow-up attempts have been completed and no further information is expected.