The victory is also the sixth straight for Shenandoah (9-2).
The Hornets led throughout over R-MC (5-4), but needed to withstand a pair of Yellow Jackets rallies.
Sisson, who finished with a game-high six goals and one assist for seven points, finally snapped the streak with an unassisted tally at 9:21.
The goal would be the first of three straight for Sisson and part of an 11-2 run that gave the Hornets their largest lead, 16-6, with 6:37 remaining.
Unfortunately for Shenandoah, the 'Jackets refused to fold their tents, scoring five straight to make it 16-11 with just under two minutes left.
SU coach Lindsey Lutz then subbed her starting midfield back in, with Sisson winning the ensuing draw and eventually coasting home to the victory.
Ten different women had at least one point on the day.
The Hornets outshot Macon 31-28, split 36 groundballs and saw R-MC win 16 of 30 draws.
SU goalie Ashley Cross made nine saves.