According to WebMD, symptoms of miscarriage at four weeks include vaginal bleeding, painful cramping and the passing of larger blood clots or tissue from the vagina. A miscarriage generally occurs over a period of several days.
Drugs.com explains that additional physical signs of a miscarriage may include a decrease in pregnancy symptoms that a woman may have been experiencing prior to miscarrying, such as morning sickness, frequent urination or sore breasts. A miscarriage generally is diagnosed by a healthcare provider with a blood test that determines if the HCG levels in a pregnant woman are decreasing. HCG levels should continually increase in a healthy pregnancy, so if the levels are decreasing, it is an easy way to diagnose a miscarriage.