rectal bleeding; irregular cycle with heavy bleeding and blood clots; irregular cycle with heavy bleeding and blood clots; polyps; This spontaneous case was reported by an other health care professional and describes the occurrence of RECTAL HAEMORRHAGE (rectal bleeding) and THROMBOSIS (irregular cycle with heavy bleeding and blood clots) in a 51-year-old female patient who received mRNA-1273 (Moderna COVID-19 Vaccine) (batch nos. 025J20A and 028L20A) for COVID-19 vaccination. The occurrence of additional non-serious events is detailed below.     No Medical History information was reported.   On 26-Dec-2020, the patient received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) 1 dosage form. On 23-Jan-2021, received second dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) dosage was changed to 1 dosage form. On 02-Jan-2021, the patient experienced RECTAL HAEMORRHAGE (rectal bleeding) (seriousness criterion medically significant), THROMBOSIS (irregular cycle with heavy bleeding and blood clots) (seriousness criterion medically significant), MENOMETRORRHAGIA (irregular cycle with heavy bleeding and blood clots) and POLYP (polyps). At the time of the report, RECTAL HAEMORRHAGE (rectal bleeding) had not resolved and THROMBOSIS (irregular cycle with heavy bleeding and blood clots), MENOMETRORRHAGIA (irregular cycle with heavy bleeding and blood clots) and POLYP (polyps) outcome was unknown.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On 18-Jan-2021, Colonoscopy: there was no bleeding, just polyps (Inconclusive) There was no bleeding, just polyps..     For mRNA-1273 (Moderna COVID-19 Vaccine) (Unknown), the reporter did not provide any causality assessments.   No concomitant medication was provided by the reporter. No treatment information was provided by the reporter.  It was reported that Patient visited her OBGYN in January who did a PAP on her. In May Patient did a biopsy which was benign, but Patient's uterus was swollen. They can see that is probably where it (the bleeding) is coming from. Patient had to do a sonogram or xray for her uterus. Now it's (the bleeding) still getting worse. Patient's OBGYN has scheduled a DNC procedure to clear out all the blood clots for next month. Patient has been visiting her OBGYN every month, but not this month since there is a plan for the procedure. Patient has not had any previous medications or treatments. Patient is relatively healthy, takes no regular medications, and has no history of diabetes or high blood pressure.  This case concerns a 51-year-old, female patient with no relevant medical history, who experienced the unexpected events of Rectal bleeding and menometrorrhagia. The events occurred approximately 8 days after the first dose of Moderna Covid-19 vaccine. The rechallenge was not applicable, as the event happened after the first dose. However, the reported polyps (?cervical polyps) remains a contributory factor. The benefit-risk relationship of Spikevax is not affected by this report.   This case was linked to MOD-2021-328732 (Patient Link).   Reporter did not allow further contact; Sender's Comments: This case concerns a 51-year-old, female patient with no relevant medical history, who experienced the unexpected events of Rectal bleeding and menometrorrhagia. The events occurred approximately 8 days after the first dose of Moderna Covid-19 vaccine. The rechallenge was not applicable, as the event happened after the first dose. However, the reported polyps (?cervical polyps) remains a contributory factor. The benefit-risk relationship of Spikevax is not affected by this report.