When a ProxySG sends objects to be analysed by an ICAP server such as Content Analysis, the results of the analysis are added to the "rs-icap-status" field which can be viewed in the proxies access log. 

Valid results include:

ICAP_NOT_SCANNED -  the object was not scanned

ICAP_NO_MODIFICATION - the object was scanned but no malware was found

ICAP_REPLACED - the object was scanned and malware detected, ICAP replaced content with an exception page