Herpes gestationis, unspecified trimester

This code describes pemphigoid gestationis, a rare, autoimmune blistering skin condition that occurs during pregnancy or the immediate postpartum period. It is characterized by intensely pruritic urticarial plaques and bullae, typically sparing mucous membranes. The condition is not related to herpes virus infection, despite its historical name.

Assign this code when documentation confirms a diagnosis of pemphigoid gestationis (herpes gestationis) in a pregnant or postpartum patient, and the specific trimester of onset or diagnosis is not specified. This diagnosis is usually made clinically, often supported by immunofluorescence studies.

• Do not confuse "herpes gestationis" with actual herpes simplex virus infections.
• If the trimester is documented, use the more specific codes O26.41-O26.43.
• Always sequence this code as a primary diagnosis when it is the reason for the encounter, or as a secondary diagnosis if it is a co-morbidity affecting pregnancy management.