The medical industry has become a big user of 3D printing/additive manufacturing. In hospitals, 3D printers serve a number of applications.

Anatomical modeling.
When it comes to planning a surgery, most surgeons previously relied on 2D imaging to examine patient anatomy. Now, with 3D printing, surgeons can use precise replicas of patient anatomy and plan detailed surgeries. If a surgery is complex, these models are used to practice every detail of a surgery first. The result is usually faster surgeries, better surgical results, and better patient recovery.
Here are a few of the stories we’ve covered recently:
https://www.makepartsfast.com/stratasys-offers-more-3d-printers-and-materials-for-anatomical-modeling/
https://www.makepartsfast.com/sinterit-launches-soft-thermoplastic-polyurethane-for-small-sls-3d-printers/
https://www.makepartsfast.com/3d-printing-creates-anatomical-models-for-better-surgical-outcomes/
https://www.makepartsfast.com/surgery-time-drops-by-33-using-3d-printing-technology/

Dental
Dentistry has been a big user of 3D printing for some time now, from invisible braces to specific surgeries for upper and lower jaws. According to a 2018 report from SmarTech Publishing, the use of 3D printing in this industry grew by more than 35% for the second year in a row, and will continue to grow in the coming years. Here are a few examples of the use of 3D printing in dentistry
https://www.makepartsfast.com/carbon-and-core3dcentres-expand-their-partnership/
https://www.makepartsfast.com/dynaflex-capitalizes-on-clear-aligner-market-using-dental-3d-printers/

Custom medical devices
A number of 3D printing vendors have developed materials that enable medical device manufacturers to make custom medical instruments and devices. See below.
https://www.makepartsfast.com/3-ways-carbon-might-have-an-edge-with-its-3d-printing-tech/
https://www.makepartsfast.com/new-3d-printable-polymer-resin-for-medical-applications/
https://www.makepartsfast.com/new-3d-printing-materials-deliver-elasticity-and-realism/

Orthotics and prosthetics
Not only is 3D printing used to develop custom orthotics, it is also used to customize limb sockets and to develop exoskeletons that could help paralyzed patients walk again.
https://www.makepartsfast.com/how-to-build-a-robotic-exoskeleton-with-digital-manufacturing/
https://www.makepartsfast.com/can-3d-printing-reinvent-the-prosthetics-industry/
https://www.makepartsfast.com/building-better-orthotics-through-biometric-scanning-and-3d-printing/

One of the earliest applications for 3D printing in hospitals was to create custom implants. This application continues.
https://www.makepartsfast.com/additive-manufacturing-technique-delivers-dissolvable-metal-for-medical-applications/

Research
3D printing is also used to help doctors research the nature of disease through three-dimensional models of molecular structures.
https://www.makepartsfast.com/color-3d-printer-models-help-explain-the-nature-of-disease-at-the-molecular-level/

Those are really just the highlights of how hospitals and the medical industry in general are using 3D printing. As doctors and researchers become more comfortable with the technology, more applications will emerge.