Combined ICD10 codes

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To code some diagnoses as part of ICD10 collection, several lines of entries in the Patient viewer tab ICD10 need to be grouped together.

To group diagnoses together, use the same Dx Priority for all of them.

Combined coding does not apply to CCI Collection (there is no priority), and there is nothing in the data that links a CCI code to the Dx it is related to.

Coding instructions


  • There are numerous situations in which multiple codes need to be listed in order to accurately reflect what's going on medically.
  • For some situations the multiple codes need to be linked together (we use the term "combined").
  • For other situations it's just a matter of ensuring that the multiple codes are all in the diagnosis list -- i.e. they don't need to be combined.
  • There are some Dxs that can only be expressed as combinations, see #Some specific cases

Clinical Situation Plus its Cause

  • Many ICD10 codes are for manifestations of disease, not a specific disorder per se.
  • In their Wiki articles it will say something like "also code cause if known" e.g: Hematemesis
  • If the cause is an infection, the Wiki article will instruct to "also code infection source", e.g: Shock, septic
  • In general, when you have a manifestation and a cause, the two codes should be combined.
    • For example, in Septic Shock that has led to liver failure, the two should be coded with the same priority.

Primary Admit Diagnosis in Combined Codes

See Primary Admit Diagnosis

Dxs that can only be expressed as combinations

Some entities can only be coded with a combination of two codes.


Some specific cases

Malignancy with Metastasis

Metastasis and their primary tumor should be coded in combination because the codes for mets don't specify the primary site, only the site of the mets.

Codes for the mets can be found at:

Metastasis codes:

Codes for the primary tumors can be found at:

Neoplastic codes:
... further results

Traumas and their Mechanisms

  • There are numerous codes for "mechanical" injuries to various body parts.
  • You can recognize these codes because their names include one or another term such as: "injury/trauma" or "traumatic".
Trauma codes:
... further results
  • What these have in common is that they are caused by an "external agent" -- such as being hit by a car, falling on your head, etc.
  • For these codes, it is required that the injury be combined with the external mechanism of the injury:
Mechanism codes:
Iatrogenic codes:

Regarding Multiple Trauma



Antibiotic resistance

Antibiotic resistance is coded as Combined ICD10 codes of the condition/pathogen and the resistance. See Antibiotic Resistant Organism for more info.

Antibiotic resistance codes:

Symptom/Sign/Test Result not needed when cause known

  • This code identifies a symptom or a sign, or an abnormal test result, not a disorder.
    • So, you must strive to code the cause of the symptom or sign, if known.
    • And if you do know the cause and code it, also coding this symptom/sign as Combined ICD10 codes is OK, but optional.
      • In the case of multi-system diagnoses, where a specific symptom/sign/test result is actually causing the hospital admission, and this would not be clear from just the condition itself, do make sure you code the symptom as well.

Patient who has Wegener's granulomatosis is admitted due to Hemoptysis. Usually coding the Hemoptysis would be optional, but Wegener's granulomatosis doesn't always present with this, and unless it is causing problems it would not alone be a reason to admit the patient, so you should code the Hemoptysis.

  • Sometimes there may be multiple symptom/sign/test result that might or might NOT be related by virtue of having the same underlying cause. Since in the absence of KNOWING that cause, such assumptions may well be incorrect, do NOT combine them together if you are not certain they actually have the same underlying cause.

Other co-codes

  • In addition to the combined coding situations listed above, you can combine codes when it makes sense to you to do so. The general guideline should be that codes be combined (instead of just both listed in the diagnosis list) when they are strongly related to each other.
  • Use your judgement. Either listing them separately, or combined ensures that they're all there.

CCMDB Data Integrity Checks

Some codes always need to be combined with one or more others. See Minimum combined codes for details.

Most infection codes require combined-coding of a pathogen (some have it implied, like Mumps), and some disorders can have a pathogen if their cause is infectious. See Bug required for details.

Transition notes

Yes, this different from how we used to use dx priorities where they had to be unique.


The records are combined by same L_ICD10.Dx Priority.

Related articles

Related articles: