Practical guide · Updated 21 August 2026
ICD-10 coding guide under Vietnam Ministry of Health rules
A concise guide to selecting the main condition, additional conditions and combined codes when completing clinical and health-insurance records.
1. Main and additional conditions
Main condition
The condition established after assessment as chiefly responsible for the episode of care. If several qualify, select the one requiring the greatest resources.
Additional condition
A coexisting condition that genuinely affects investigation, care, treatment, length of stay or resource use during the episode.
Key rule: record one main condition only. Do not add historical conditions that did not affect the episode.
2. When to reselect the main condition
- Greater clinical importance or resource use: select the condition that best matches the actual surgery, treatment, specialty and care delivered.
- Confirmed disease over a symptom: when a symptom is explained by a diagnosed and treated disease, use the confirmed disease.
- Greater specificity: choose the diagnosis that most specifically describes the documented condition.
- Insufficient evidence: retain the documented first-listed diagnosis when the official reselection rules do not support another choice.
3. Dagger, asterisk and supplementary codes
- Dagger (†): describes the underlying disease and is normally sequenced first.
- Asterisk (*): describes the manifestation in an organ; it is an additional code and must not be used alone.
- Review both members of a required pair and the notes attached to each code.
- Use supplementary codes for infectious agents, external causes, sequelae and other details when required by the classification.
4. Common coding scenarios
No confirmed diagnosis
Code the principal symptom, sign or abnormal finding in Chapter XVIII, or the appropriate observation code when a suspected condition has been ruled out.
Acute and chronic disease
Where separate codes exist, sequence the acute episode or exacerbation first and the chronic condition as additional.
Complications and sequelae
Sequence the manifestation being treated, then add the sequela or causal code as directed by the classification.
Follow-up and special procedures
Use the appropriate Z code for follow-up, chronic prescriptions, chemotherapy, radiotherapy, dialysis or other special care.
Final checklist
- ✓ One main-condition code only.
- ✓ Most specific supported code selected.
- ✓ Additional conditions affected care.
- ✓ Required †/* pairs are complete.
- ✓ Inclusions, exclusions and notes reviewed.
- ✓ Diagnosis and insurance data are consistent.
Basis and scope
This guide summarises Ministry of Health coding principles and the indicators applicable in 2026. Current legal instruments and the actual clinical record prevail where any difference arises.
