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Cheryl Iverson

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Semicolons represent a more definite break in thought than commas. Generally, semicolons are used to separate 2 independent clauses. Often a comma will suffice if sentences are short; but when the main clauses are long and joined by coordinating conjunctions or conjunctive adverbs, especially if 1 of the clauses has internal punctuation, use a semicolon.

Separating Independent Clauses.

Use a semicolon to separate independent clauses in a compound sentence when no connective word is used. In most instances it is equally correct to use a period and create 2 sentences.

The conditions of 52% of the patients improved greatly; 4% of the patients withdrew from the study.

However, if clauses are short and similar in form, use a comma.

Seventy grafts were patent, 5 were occluded.

Use a semicolon between main clauses joined by a conjunctive adverb (eg, also, besides, furthermore, then, however, thus, hence, indeed, yet) or a coordinating conjunction (and, but, or, for, nor) if 1 of the clauses has internal punctuation or is considerably long.

The patient’s fever had subsided; however, his condition was still critical.

The word normal is often used loosely; indeed, it is not easily defined.

Introduction to the knowledge, skills, and attitudes relevant to safety should begin in medical and nursing school; eg, the first 2 years of medical school may be the most appropriate to learn error science and principles of leadership.


For clarity, use semicolons between items in a complex or lengthy enumeration within a sentence or in an enumeration that contains serial commas in at least 1 of the items listed. (In a simple series with little or no internal punctuation, even with multiword elements, use commas.)

A number of questions remain unresolved: (1) whether beverages that contain caffeine are an important factor in arrhythmogenesis; (2) whether such beverages can trigger arrhythmias de novo; and (3) whether their arrhythmogenic tendency is enhanced by the presence and extent of myocardial impairment.

The photomicrographic illustrations of the gross and microscopic features of normal skin, Spitz congenital and dysplastic nevi, lentigines, and melanoma demonstrated the complexity of pigmented lesions.

In less formal writing and where the last element of a series is also a series, commas are acceptable provided that clarity is preserved.

The statistician addressed limitations in case-control studies, cohort studies, and randomized, double-blind, controlled trials.

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