Final answer:
The most likely diagnosis for the 68-year-old woman with severe abdominal pain is acute appendicitis.
Step-by-step explanation:
The most likely diagnosis for the 68-year-old woman with severe abdominal pain is acute appendicitis. Appendicitis is characterized by sudden onset of severe abdominal pain, which often starts around the umbilicus and then migrates to the right lower quadrant of the abdomen. Other symptoms may include fever, nausea, vomiting, and loss of appetite.