ICD-10-CM Chapter 15 codes generally have sequencing priority over codes from other chapters when a condition complicates pregnancy, childbirth, or the puerperium.

Therefore, when pyelonephritis complicates pregnancy, the appropriate obstetric complication code is generally sequenced first, with additional code(s) used as instructed to identify the specific infection or organism.

This principle is important because ordinary principal-diagnosis logic can be modified by chapter-specific instructions. CDI specialists working with obstetric cases therefore must determine whether the pregnancy affects management and whether the condition is documented as complicating pregnancy.

The only major exception would be when the provider specifically determines that the pregnancy is incidental to the encounter and the applicable coding requirements for incidental pregnancy are met.

A symptom code does not generally supersede an established definitive diagnosis. Likewise, the fact that an infection could occur outside pregnancy does not negate Chapter 15 sequencing when it is complicating the pregnancy.

Correct gestational-age documentation is also important because an additional code may be required to identify the specific week of gestation.

CCDS Reference Topics: Obstetric coding; Chapter 15; sequencing priority; infection in pregnancy; principal diagnosis.

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