Z3A.18 — 18 weeks gestation of pregnancy

Billable

Is Z3A.18 billable?

Yes — Z3A.18 is billable for FY2027. Z3A.18 is a valid, billable ICD-10-CM code at the highest level of specificity in its branch. Z3A.18 may be submitted for encounters from October 1, 2026 through September 30, 2027.

Z3A.18 at a glance

Code	Z3A.18
Description	18 weeks gestation of pregnancy
Billable	Yes
Code set	ICD-10-CM FY2027
Valid for encounters	October 1, 2026 – September 30, 2027

What Medicare edits apply to Z3A.18?

The Medicare Code Editor screens inpatient claims before they are grouped. These edits name Z3A.18 directly.

Cannot be a principal diagnosis — MCE edit 9

CMS will reject this code as the principal diagnosis on an inpatient claim. It describes something other than the condition chiefly responsible for the admission.

Which MS-DRGs does Z3A.18 group to?

Z3A.18 sits in MDC 23 and helps define the logic of 1 MS-DRG (version 44, FY2027). Which one a stay actually groups to also depends on procedures and secondary diagnoses.

951Other Factors Influencing Health Statusmedical

How is Z3A.18 listed in the Alphabetic Index?

These are the routes through the Alphabetic Index that lead to Z3A.18. They show the wording a clinician may have documented, which often differs from the Tabular description.

Pregnancy › weeks of gestation › 18 weeks (single) (uterine)

Code first — inherited from Z3A

The underlying condition below must be sequenced before Z3A.18. Z3A.18 describes a manifestation and cannot be the principal or first-listed diagnosis.

obstetric condition or encounter for delivery (O09-O60, O80-O82, O94-O9A)

How long has Z3A.18 existed?

Z3A.18 has been in ICD-10-CM since at least FY2016, the earliest fiscal year on record here.

Derived from the official order files for FY2016–FY2026. FY2017 and FY2020 publish no order file, so those years are not covered.