There's No Such Thing as Safe Sex

This is so well-written, I took it right from the NY Post:

When your parents told you about the birds and the bees, we bet they didn’t tell you that a penis up your poop chute could get you preggers.
Well, luckily, that’s because about 999,999 times in a million, it can’t. When Brian Steixner, M.D., a urologist with the Jersey Urology Group in Atlantic City, was in med school, though, he witnessed the “lucky” one in a million.
One night, a young, pregnant woman came into the emergency department complaining of spotting. While it’s relatively common for women to have light spotting during pregnancy, the blood was coming from her rectum. That — not so common.
The woman was born with what’s called a cloacal malformation. Meaning: When she was born, she didn’t have a urethra, vagina and anus. She just had one hole, called a cloaca. (FYI, birds have them.) The condition is incredibly rare, occurring in about one in 25,000 female live births, says Steixner (and it only occurs in girls — lucky us). While no one knows what causes it, it’s usually diagnosed at birth and repaired right away so that the baby has a separate urethra, vagina and rectum.
That’s what happened in this woman’s case. However, something went wrong. Either the surgery was botched or in response to the trauma of surgery, her body formed a fistula (an abnormal connection between organs), and her uterus fused to her rectum. So every month when Aunt Flo came to town, she had her period rectally. Meanwhile, her vagina was a dead end leading nowhere.
Crazy, right? During Steixner’s conversation with the woman, he says she mentioned that she exclusively had anal sex prior to getting pregnant. Well then, that would explain it: She got pregnant through anal sex. “It blew my mind,” he says. A few months later, she had a C-section (the doctors didn’t think she should attempt to “poop” out the baby), and the child was healthy, he says.
Steixner says he doesn’t know what happened to the woman after she had the baby. And while the case of a woman getting pregnant through anal sex due to a cloacal malformation is incredibly rare, being born with a cloaca can be incredibly difficult, even if it is repaired at birth.
“Building the walls to separate the three passages [the urethra, vagina and rectum] is delicate work,” he says. “The longer the walls need to be built, the closer surgeons get to the urethral and anal sphincters. Some women suffer from leakage of urine and stool their entire lives. It’s a huge psychological and quality-of-life issue.”
However, since you’re probably wondering, even if the urethra and anus don’t work 100 percent perfectly after cloacal repairs, everything — vagina included — does look pretty “normal.” Of course, no two vaginas look the same (true story!), but chances are, no guy would ever be down there, pause and ask, “What happened here?”