Ob-Gyn Coding Alert

Question: What are the correct ICD-9 codes for 1) atypical squamous cells of undetermined significance, 2) low-grade squamous intraepithelial lesion, and 3) high-grade squamous intraepithelial lesion?

Minnesota Subscriber

Answer: Atypical squamous cells of undetermined significance (ASCUS) means there are some squamous cells present that are not normal, but they may be due to inflammation (95 percent to 98 percent) or premalignant change (2 percent to 5 percent). This result is always coded as 795.0 (Nonspecific abnormal Papanicolaou smear of cervix).

Low-grade squamous intraepithelial lesion (LGSIL) means some squamous cells are present that may come from an early premalignant lesion. This is generally thought to be dysplasia or CIN II (cervical intraepithelial neoplasia II) and can be coded as 622.1 (Dysplasia of cervix [uteri]).

High-grade squamous intraepithelial lesion (HGSIL) means some squamous cells are present that may come from an advanced premalignant lesion, and this may be considered by some pathologists to be carcinoma in situ, or CIN III (cervical intraepithelial neoplasia III), coded as 233.1 (Carcinoma in situ; cervix uteri).

However, the Bethesda reporting method for Pap smears also indicates that some HGSIL results may only be CIN II so unless you have a confirmation of CIN III, you should code the lesser condition of 622.1.