O26 vs R03.1

O26 and R03.1 can never be reported together. ICD-10-CM declares them mutually exclusive with an Excludes1 note, meaning the two conditions cannot occur in the same patient — so exactly one of them is correct for any given encounter.

The official note, declared on R03.1

maternal hypotension syndrome (O26.5-)

O26

Maternal care for other conditions predominantly related to pregnancy

Not billable

Chapter 15: Pregnancy, childbirth and the puerperium
Section: O20-O29

R03.1

Nonspecific low blood-pressure reading

Billable

Chapter 18: Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified
Section: R00-R09

Indexed under

Abnormal, abnormality, abnormalities › blood pressure › low reading
Decrease › blood › pressure (d)
Low › blood pressure › reading
Pressure › hyposystolic › incidental reading, without diagnosis of hypotension
Blood › pressure › low › incidental reading, without diagnosis of hypotension

These two codes sit in different chapters of the Tabular List, which is usually the clearest signal that they describe different underlying processes rather than different degrees of the same one.

Excludes1 is not always absolute: where two conditions covered by the note are genuinely unrelated, CMS guidance permits reporting both. Document the reasoning rather than assuming it. More on Excludes1 vs Excludes2 · FY2027