This expertise represents your character's capabilities with conventional, non-supernatural medical practices and treatments.
When you take a point in Medical expertise, choose a specialization between Field Medic and Doctor. Regardless of your choice, your character will be generally better at medical procedures as they gain ranks of expertise, but the specialization grants extra capabilities appropriate to it -- for example, a Doctor can act as a Field Medic if they must, but will not be as good at it, and vice versa. If you so choose, you may spend a Feat slot when one is available to take the other specialization in addition to your initial choice.
No Points: You might have no medical knowledge at all, maybe you learned basic first aid and CPR as a Thranta Scout, or maybe you even spent time at medical school. Regardless, you could potentially be the difference between someone bleeding out on the floor and making it to the ambulance by applying pressure to a wound, or the one to keep someone alive with chest compressions until a more qualified person comes by. You can apply basic first aid measures and kolto stims, but not much more than that.
1 Point: You've gone beyond theoretical and academic knowledge and now have some experience to back it up. You know what to do for most common injuries or ailments, and can be reliably trusted to keep someone alive or nurse them back to health so long as they aren't too far gone before you get to them. You could fit in well working as a nurse at a medical center or as an EMT.
2 Points: You've treated enough patients in various degrees of health to have picked up some tricks and know-how that has taken your capabilities further. As a Field Medic you're able to stabilize and treat serious wounds to a better degree and do more with less; as a Doctor, you can improve people's recovery times with careful treatment and counteract more serious issues with better success.
3 Points: Any hospital or squad would be thrilled to have you because yours are a healer's hands. Whether you're in the field or the med center, you treat patients with incredible efficiency, effectiveness, and expediency. As a Field Medic, if you get to a wounded person quick enough, they might not even NEED to go to the hospital after depending on how bad their injuries are. As a Doctor, you can treat extreme cases with confidence, potentially cutting down significantly on a patient's recovery time and markedly boosting their quality of life while they do recover.
3☆ (Mastery): You may well be one of the best, if not THE best at what you do for many, many parsecs. You can probably judge exactly what a patient needs with just a quick examination, diagnosing issues they may not even have been aware they had. If you're on the case, miracles are likely to happen and lives will almost certainly be saved - outcomes that might otherwise seem impossible are suddenly on the table.