Carcinoma in situ is a frequent finding in pregnancy when cytologic methods are applied as a routine screening procedure. Such testing has been done without risk and has been applied at all stages. Cancer found when unsuspected and in a preclinical state rarely demands radical treatment. Modern management of early lesions which are preinvasive calls for conservative measures and cytologic follow-up, in contrast to clinical cancer, which demands immediate and often radical therapy. The recommended method for adequate biopsy is the cold-knife cone or "ring-biopsy" with the Ayre-Scott conization knife with disposable blade. Infiltration with 100 to 300 ml. of a saline-epinephrine solution makes it possible to excise the surgical specimen without loss of blood. Performed preferably after the third month of pregnancy, the conization procedure is safe.
Ayre JE, Scott JW. Carcinoma In Situ in Pregnancy. JAMA. 1961;176(2):102–105. doi:10.1001/jama.1961.03040150018005