Final answer:
Abdominopelvic cramping and minor bleeding 3 weeks after the last menstrual period could be implantation bleeding.
Step-by-step explanation:
A brief episode of abdominopelvic cramping and minor bleeding approximately 3 weeks after the last menstrual period could be attributed to implantation bleeding. Implantation bleeding occurs when a fertilized egg attaches itself to the lining of the uterus. It is usually light and lasts for a short period of time.