J91.8Pleural effusion in other conditions classified elsewhere

J91.8 is the ICD-10-CM diagnosis code for pleural effusion in other conditions classified elsewhere. It belongs to category J91 (pleural effusion in conditions classified elsewhere), block J90-J94 (other diseases of the pleura) and chapter 10 (diseases of the respiratory system). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.

Within J91, choose J91.8 (Pleural effusion in other conditions classified elsewhere) only when documentation doesn't support a more specific option: malignant pleural effusion (J91.0).

Code first underlying disease, such as: filariasis (B74.0-B74.9) and influenza (J09.X2, J10.1, J11.1).

As a secondary diagnosis it is a CC (complication or comorbidity), which can move an inpatient stay into the "with CC" MS-DRG of its family, unless the principal diagnosis excludes it.

In MS-DRG v44.0, it is part of the grouping logic for DRG 186 (Pleural Effusion with MCC, relative weight 1.5835), DRG 187 (Pleural Effusion with CC, relative weight 1.0001), DRG 188 (Pleural Effusion without CC/MCC, relative weight 0.6654), DRG 791 (Prematurity with Major Problems, relative weight 4.1075) and DRG 793 (Full Term Neonate with Major Problems, relative weight 4.2195), in MDC 04 (Diseases and Disorders of the Respiratory System) and MDC 15 (Newborns and Other Neonates with Conditions Originating in the Perinatal Period), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.

It is a manifestation code, so it describes the effect of an underlying disease and can't be the principal diagnosis. Code the underlying condition first.

It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.

Before ICD-10, this condition was coded in ICD-9-CM as 511.9 (unspecified pleural effusion).