Use parentheses to indicate supplementary explanations, identification, direction to the reader, or translation
- A known volume of fluid (100 mL) was injected.
- The differences were not significant (P >.05).
- One of us (B.O.G.) saw the patient in 2006.
- Asymmetry of the upper part of the rib cage (patient 5) and pseudarthrosis of the first and second ribs (patient 8) were incidental anomalies (Table 3).
- Of the 761 hospitalized patients, 171 (22.5%) were infants (younger than 1year).
If there is a close relationship between the parenthetical material and the rest of the sentence, commas are preferred to parentheses.
- The hemoglobin level, although in the normal range, was lower than expected.
If the relationship in thought after the expressions namely (viz), that is (ie), and for example (eg) is incidental, use parentheses instead of commas.
- He weighed the advice of several committee members (namely, Jones, Burke, and Easton) before making his proposal.