Opioids are derivatives of morphine, a narcotic pain reliever. The term opioid generally refers to morphine and other opium poppy-based medications. Opioids work by decreasing pain signals being transmitted through the nervous system, which suppresses our perception of pain.
When you swallow semen, Semen and sperm go down into your stomach, where they are digested with all your other food. There is no passage connecting your stomach to your ovaries. You can not get pregnant from swallowing sperm. If the donor has no STDs, it is perfectly safe.
Sperm are very tiny and resilient things! So all it takes is a small hole (where the tube was tied and burned) for them to get through and if you've ovulated, then the sperm can fertilize the egg. But the reason so many of these pregnancies are ectopic is because the fertilized egg starts to grow and cells divide. So then it can't fit back through the tiny hole the sperm was able to slip through. So the fertilized egg/cells implants wherever it's able, which can be on either end of the cut/burnt Fallopian tube.