I would use: O36.83-- Maternal care for abnormalities of fetal heart rate or rhythm, xxx trimester
Erin Kornovich, CPC | Coding Specialist II – Maternal Fetal Medicine & Physiatry
P: 320-251-2700, ext. 52373
ICD-10 code O36.891 - O36.899 (Maternal care for other specified fetal problems) would be used for fetal arrhythmia for patients not in labor or delivery.