Laparoscopic surgery was done through three small incisions, and after an hour of searching, the appendix was not located.
After the operation, the doctor claimed the patient did not tell him she had had an appendectomy possibly during either gallbladder or tubal ligation surgery in the past. On one of those occasions, she may have had an incidental appendectomy—removal of a normal appendix to theoretically prevent appendicitis in the future. It's an operation rarely done today.
She was discharged after a brief hospital stay. There was a bit of a fuss about "unnecessary surgery" and what, if anything, the surgeon told the patient after the procedure. A phone conversation with him was secretly recorded by the patient's daughter. An investigation is underway.
You might be interested in two questions. Can you get appendicitis again after you've had an appendectomy? Other than previous surgery, is there another explanation for a patient who does not have an appendix?
Some people don't remember whether they've had their appendices removed, especially if it was done many years ago or at the time of another procedure. Maybe this patient was never told that she had had an appendectomy.
Even if she had had undergone an appendectomy, she could have had another attack of appendicitis.
There is an entity called "stump appendicitis" which occurs when the appendix is only partially removed during surgery.
A 2006 literature review found 36 cases of stump appendicitis (1). Considering there are more than 250,000 appendectomies done every year in the US, stump appendicitis is a rare. Here's what it looks like on a CT scan. (2)
And here is a photo of appendicitis in a rather long stump about to be removed during laparoscopic surgery. (3)
Another possibility is duplication of the appendix which has been reported to occur in 0.004-0.009% of the population. (4) Either or both of the two appendices can become inflamed.
Maybe our 69-year-old lady never had an appendectomy. Congenital absence of the appendix occurs in 1 of 100,000 people. However, she probably wouldn't have had an appendiceal orifice if her appendix was absent when she was born. (5) This is what absence of the appendix looks like at surgery. (6)
Bottom line: Appendicitis can recur or may not be present in some individuals.
Acknowledgment: Thanks to my Twitter follower @davepaskar for stimulating me to write this post.
References available upon request.