Final answer:
The correct ICD-10-CM code for a spontaneous complete abortion with retained products of conception and no complications mentioned is 'O03.6 - Incomplete spontaneous abortion without complication'.
Step-by-step explanation:
The ICD-10-CM code for a patient who had a spontaneous complete abortion three days ago, who returns to the emergency department (ED) and is still bleeding due to retained products of conception (POC), would likely be 'O03.6 - Incomplete spontaneous abortion without complication' since the code specifically addresses spontaneous abortion with retained products of conception without mention of any complications.