Final answer:
The rupture of an appendix leads to Peritonitis, which is a serious inflammation of the peritoneum and requires emergency surgery and antibiotics.
Step-by-step explanation:
If an appendix ruptures, the serious complication it causes is Peritonitis. Peritonitis is a life-threatening inflammation of the peritoneum, which is the thin tissue that lines the inner wall of the abdomen and covers most of the abdominal organs. When the appendix bursts, it releases infectious materials into the peritoneal cavity, leading to this severe inflammation. Emergency surgery is often required to remove the damaged appendix and clean the abdominal cavity, accompanied by intensive antibiotic therapy to treat the infection.