The probe is pointing to one of the kidneys. To find the kidneys, you may need to move around your spleen to find it (or it may be closer to the "surface" that normal, that can sometimes happen). They are usually on the side of the abdominal wall, attached right onto the wall, one on each side. it is easy to spot. just look for a dark bean shaped organ on the side of the wall. Kidneys are essential to almost all animals that have them-- they are necessary for proper functioning of the urinary system, and also maintain various states of homeostasis. The kidneys filter blood as well, shipping off the waste to the urinary bladder where it will later be excreted and removed from the body.
The urinary bladder is where the kidneys store urine until it is excreted from the body. this is easily found when looking near the umbillical cord area, it is attached to the top of the abdominal wall (which you should have cut open) it is a large sac-like organ.
The ureters are tubes of smooth muscle that pump urine from the kidneys to the urinary bladder for storage. It can be easily found near the bladder of the pig. If you cannot locate the bladder to find the ureter, try looking from the kidney (ureters connect kidneys with the bladder).