Blood tests are probably the most common way. To me, I think it's incredible that we can learn so much about a relatively hard-to-get-to organ from our blood. If this intrigues you, too, I explain more about this in Blood Tests for Hepatitis C.
Nobody likes to get poked and prodded with needles, especially with one big enough to actually sample a piece of your liver. As uncomfortable as this may sound, for people with hepatitis, this is a good thing. Sometimes doctors need to see exactly what's going on inside your liver. The biopsy is a clever way to actually remove a small piece of liver tissue and study it.
Finally, there's also imaging technology, like CT scans and MRIs. These powerful machines figuratively turn our entire abdomens into giant windows, bringing light to a hidden organ. Of course, a combination of all three are sometimes necessary. To me, I'm just happy we have the ability to "peek" inside. For more information about all these methods and more, check out Diagnosing Hepatitis.
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