What's the reason for being unable to have a bowel movement or urinate on the first day of menstruation?

During menstruation, women may experience physical discomforts such as abdominal pain and backache. These symptoms can sometimes affect bowel and bladder function. Feeling difficulty in defecation or urination on the first day of menstruation might be caused by uterine contractions. The uterus undergoes strong contractions to expel the endometrial lining, and these contractions can sometimes extend to the nearby intestines, causing a temporary sensation of constipation or urinary retention. Additionally, hormonal changes in the body during menstruation may also affect intestinal motility, leading to difficulty in bowel movements. However, if this situation persists for a prolonged period or is accompanied by other severe symptoms such as intense abdominal pain, blood in the stool, or abnormal urination, it could indicate other health issues, such as pelvic inflammatory disease, intestinal obstruction, or urinary tract infection. Therefore, if symptoms persist or cause significant discomfort, prompt medical consultation and examination are recommended.