Final answer:
The case should be coded as Z51.11 for chemotherapy followed by C56.1 for right ovarian cancer, reflecting the current reason for admission being chemotherapy for the previously treated cancer.
Step-by-step explanation:
When coding medical cases such as a patient being admitted for chemotherapy after surgery for right ovarian cancer, the main consideration should be sequencing the codes to reflect the current episode of care. The primary diagnosis for the admission is the chemotherapy treatment, and thus the code for chemotherapy should be sequenced first. In this case, the correct code for chemotherapy administration is Z51.11 (Encounter for antineoplastic chemotherapy). This should be followed by the code for the malignancy, which in the case of ovarian cancer would generally be C56.1 (Malignant neoplasm of right ovary) since the surgery was for right ovarian cancer. Therefore, the correct coding and sequence would be Z51.11 for chemotherapy, followed by C56.1 for the right ovarian cancer that the chemotherapy is treating.