In simple words: Carcinoma in situ (CIS) of the cervix is a pre-cancerous condition where abnormal cells are found on the surface of the cervix. These cells have not yet spread to deeper tissues. It is often caused by HPV infection and may not have noticeable symptoms in the early stages.

Carcinoma in situ of cervix uteri. Includes: cervical adenocarcinoma in situ, cervical intraepithelial glandular neoplasia, cervical intraepithelial neoplasia III [CIN III], severe dysplasia of cervix uteri. Excludes1: cervical intraepithelial neoplasia II [CIN II] (N87.1), cytologic evidence of malignancy of cervix without histologic confirmation (R87.614), high grade squamous intraepithelial lesion (HGSIL) of cervix (R87.613), melanoma in situ of cervix (D03.5), moderate cervical dysplasia (N87.1)

Example 1: A 30-year-old female presents with abnormal vaginal bleeding. A Pap smear reveals CIN III. Colposcopy and biopsy confirm carcinoma in situ of the cervix., A routine Pap smear in a 25-year-old female shows atypical glandular cells. Further examination and biopsy lead to a diagnosis of adenocarcinoma in situ of the cervix., A 45-year-old female undergoes a hysterectomy for fibroids. Incidentally, carcinoma in situ is found in the cervix upon pathological examination.

Documentation should include evidence of abnormal cervical cytology (Pap smear), colposcopic findings, and biopsy results confirming the diagnosis of carcinoma in situ. Details of any procedures performed, such as LEEP or cone biopsy, should also be documented.