A month after he was treated for blood clots in his lungs, former Vice President Dan Quayle returned to Indiana University Medical Center today with appendicitis. The 47-year-old Quayle was planning to announce his decision on whether to run for President in '96 this week. He is expected to be hospitalized for at least seven days, during which his severely enlarged appendix will be removed. Quayle was quoted as saying he was eager to get rid of the organ: "I don't need it anyway." A Quayle spokeswoman said doctors discovered the appendix problem during follow-up treatments for Quayle's clots, or pulmonary embolisms. Dr. Bruce A. Perler, an associate professor of surgery at Johns Hopkins University, told TIME Daily it's unlikely the two medical problems were related. But he added that the embolisms -- which are rare -- have in some cases posed dangers during operations.