What do we mean that ICD-10 is more specific?

While there are dozens of minor distinctions between ICD-9 and ICD-10 the three fundamental changes are:

There is expanded detail for many conditions (e.g., viral hepatitis has been expanded from ICD-9 070, a single 3-digit category, to ICD-10 B15-B19, five 3-digit categories
Conditions were transferred around the classification (e.g., hemorrhage has been moved from the circulatory chapter to the symptoms and signs chapter)
ICD codes used for morbidity and mortality were forked (technically the ICD-10 that most care practitioners are interested in is the ICD-10-CM)

While most healthcare providers have familiarized themselves with the transfer classifications those who aren’t responsible for claims processing don’t really understand what the distinctions were in terms of complexity. Let’s take an easy example of burns which helps to make the distinction more specific. In ICD-9 there were a few codes associated with burns.

940) Burn confined to eye and adnexa

941) Burn of face, head, and neck

942) Burn of trunk

943) Burn of upper limb, except wrist and hand

944) Burn of wrist(s) and hand(s)

945) Burn of lower limb(s)

946) Burns of multiple specified sites

947) Burn of internal organs

948) Burns classified according to extent of body surface involved

949) Burn, unspecified

Then the burn was subsequently secondarily coded using the rule of 9s. The rule of 9’s cut the body 12 sections 11 were weighted 9% each (head, chest, abdomen, upper back, lower back + buttocks, left arm, right arm, front left leg, rear left leg, front right leg, read right left ): and the perineum weighted the final 1%. Given ICD-9 codes a health provider, insurance company or a government agency could determine the degree of burns and over a rough percentage of the body but that was about it.

With ICD-10 quite literally there are hundreds of codes used for burns. The system doesn’t use secondary coding and each burn on each part is classified individually. For example:

T24.121D Burn of first degree of right knee, subsequent encounter?

T24.121S Burn of first degree of right knee, sequela

T24.122D Burn of first degree of left knee, subsequent encounter

T24.122S Burn of first degree of left knee, sequela

and when even more specificity is needed because of internal external problems ICD-10 introduces even more coding:

T27.0XXD Burn of larynx and trachea, subsequent encounter

T27.0XXS Burn of larynx and trachea, sequela

T27.1XXD Burn involving larynx and trachea with lung, subsequent encounter

T27.1XXS Burn involving larynx and trachea with lung, sequela

T27.2XXD Burn of other parts of respiratory tract, subsequent encounter

T27.2XXS Burn of other parts of respiratory tract, sequela

T27.3XXD Burn of respiratory tract, part unspecified, subsequent encounter

T27.3XXS Burn of respiratory tract, part unspecified, sequela

This kind of coding is only practical because EMR are directly translating medical notations rather than having human coders / billing people translating notes for billing. The core of MU2 is removing the need for expert / human judgment from the seams between subsystems in the EMR. Architecting the systems that handle these seams has been the core of what companies like Nalashaa have been doing to move providers and ISVs across the country towards MU2 and ICD-10.