Excludes1 pair

O26- vs R03.1

O26 and R03.1 are not coded together. ICD-10-CM declares them mutually exclusive with an Excludes1 note — the two conditions are not expected to occur together, so exactly one of them is normally correct for a given encounter. The Official Guidelines carve out one exception: if the two conditions are clearly unrelated to each other, both may be reported.

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 (nonspecific)
  • Decrease › blood › pressure
  • Low › blood pressure › reading (incidental) (isolated) (nonspecific)
  • 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