In 1988, a 15-year-old girl living in the small southern African nation of Lesotho

Yeah very reliable for that time to believe such a thing. Not to mention the location in a small African village that wasn't as equipped with medical knowledge. Not to mention in that very source you are linking:

But some doctors are still suspicious of, or at least bewildered by the tale.

Dr. Howard A. Zacur, a reproductive endocrinologist at Johns Hopkins, also had doubts. "The case report here suffers from the fact that an individual with a completely obstructed vaginal outlet would have been expected to have blood accumulation in the vagina, and/or uterus," he wrote in an e-mail.

So basically, while there might be an astronomically small chance this is true, there are plenty professional doctors (so not some lowlife redditor like myself) that doubt the story.

With that, there's no fact it really did happen and it sounds very unlikely. In short, don't believe everything you read, even if it's in a paper by a doctor. Anything could have happened between the actual events and word finally coming out to the western world.