The Y2K of health insurance is coming. On October 1, 2015, the entire US healthcare system will switch over to the 10th revision of the International Classification of Diseases, which has, well, ballooned to far more than a classification of diseases. Do you have a cough? A paper cut? A dune buggy injury? There's a code for that.

If you've ever scrutinized a medical bill—like really scrutinized one—then you've seen these codes. To get reimbursed by insurance companies, doctors' offices have coders who break down every patient interaction into a series of alphanumeric codes. It's always been a cumbersome process to choose from 18,000 codes. With ICD-10, that number is ballooning to 140,000.

And you don't get to 140,000 without getting super super specific about all the ways a human body can go wrong. The manual lists 45 pages of just traffic-related injuries. And then it gets a lot more obscure. Examples? Oh, boy have we got examples.

V95.4 Spacecraft accident injuring occupant—Choose from specific codes for: Unspecified spacecraft accident injuring occupant, Spacecraft crash injuring occupant, Forced landing of spacecraft injuring occupant, Spacecraft collision injuring occupant, Spacecraft collision with any object, fixed, moveable or moving, Spacecraft fire injuring occupant, Spacecraft explosion injuring occupant

V86.43 Person injured while boarding or alighting from dune buggy

V90.27 Drowning and submersion due to falling or jumping from burning water-skis

W56 Contact with nonvenomous marine animal—Choose from: bitten, struck or other contact with dolphin, sea lion, orca, or other nonvenomous marine animal. (Yes, venomous marine animals belong to another category.)

There are also codes for when an injury occurred:

Y93.J1 Activity, piano playing

Y93.81 Activity, refereeing a sports activity

Y93.84 Activity, sleeping

And where:

Y92.253 Opera house as the place of occurrence of the external cause

Y92.311 Squash court as the place of occurrence of the external cause

Y92.113 Driveway of children's home and orphanage as the place of occurrence of the external cause

All these obscure codes get at a real point though: ICD-10 gets incredibly granular. A relatively common injury—such as a badly healed fracture—could rack up 2,595 different codes, according to the healthcare technology company OptumInsight. Hospitals and insurance companies have had years to prep for ICD-10, but they're still expecting hiccups. The New York Times reports some hospitals have taken out lines of credit, anticipating the switch will make it harder to get reimbursed in time.

Best case scenario, October 1 goes off like the real Y2K, where a lot of planning prevented any major catastrophe. Either way, people are probably going to be dealing with some F43.0 (acute stress reaction).