The F3 (debug) key may be of some help, but generally speaking:
Special forces are normally the only fleet travelling between wormholes while not being a carrier.
If you have a scout picket, you can simply go to the galaxy map and look for a higher than normal concentration of AI ships in a planet that is not on alert. Turn on the threat filter... if you have no threat in that system, it is likely the patrol.
Oftentimes, if the patrol no longer has something to react to, you can catch it stalled in very obvious lines. Particularly if you have a stealthed fleet present.
Threat (depending on game options) will usually be found in a carrier (CPAs), or hovering about 20,000 or so off of any wormhole, not lying on any direct path.
Patrols will only react to your presence in particular systems, and only found in AI systems barring certain special conditions (rally guardians?). The conditions that cause a patrol to defend a system are pretty common although generally avoidable. ARS, Broken Golem, etc... if you want to take it, they'd want to defend it. However, you can find a relatively safe route between you and your destination, or draw the patrol into ambush, followed by a beachhead to wear them down.