One of the most common intestinal parasites in the United States, Giardia, can cause the stool to appear yellow—and have a soft or liquid consistency—because it causes the food to move quickly through ...

Jozsef Zoltan Varga/Getty Images When black poop happens, family practitioners like Christine Traxler, MD, and pediatricians like Alison Mitzner, MD, are often the first ones their patients call. As ...

Stool culture. This test looks for any abnormal bacteria in your digestive tract that may cause diarrhea and other problems. A small stool sample is collected and sent to a lab. In 2 or 3 days, the ...