Final answer:
An ectopic pregnancy is the likely explanation for the described symptoms of a palpable, irregular protuberance in the lower abdomen and moderate vaginal bleeding.
Step-by-step explanation:
The symptoms described, including a palpable, irregular protuberance in the lower abdomen and moderate vaginal bleeding, are indicative of an ectopic pregnancy. Ectopic pregnancy occurs when a fertilized egg implants outside of the uterus, most commonly in the fallopian tube. This can cause vaginal bleeding and abdominal pain. It is a medical emergency that requires immediate attention.