Disclosed are systems and methods for inspecting and monitoring an inner surface of a pipeline. One system includes a pig arranged within the pipeline and having a housing that defines a conduit therein for providing fluid communication through the pig, one or more optical computing devices arranged on the conduit for monitoring a bypass fluid flowing through the conduit. The one or more optical computing devices including at least one integrated computational element configured to optically interact with the bypass fluid and generate optically interacted light, and at least one detector arranged to receive the optically interacted light and generate an output signal corresponding to a characteristic of the bypass fluid. A signal processor is communicably coupled to the at least one detector of each optical computing device for receiving the corresponding output signals and determining the characteristic of the fluid.