After a disaster, we know to expect no grocery stores, no pharmacies, no running water, no electricity, and so on. Quite possibly, access to a hospital would be limited or non-existent too. Guess what every doctor and medical facility is dependent upon and would also be out of commission- the lab.
One of modern bio-medicine’s great strengths is its diagnostic capabilities. Another is its surgical interventions. Surgeries and accurate diagnosis are dependent upon the results of lab tests. Blood and urine tests tell us important information like glucose tolerance, if a woman is pregnant, and how to pick the correct antibiotic for infections