The Ambulatory Sentinel Practice Network (ASPN) conducted an observational study of usual primary care of spontaneous abortion (SAB). Forty-nine practices in 18 states and four Canadian provinces reported and audited 171 SABs. Contrary to recommendations in some texts, 40 percent were managed completely in the office and/or at home, and only 51 percent had a dilation and curettage (D&C). SABs occurring later in pregnancy were more likely to be managed in the emergency room/hospital, receive consultation, and have a D&C. Patients managed with D&C had a greater frequency of excessive blood loss at diagnosis, but otherwise they did not differ in terms of complications at diagnosis or follow-up from those who did not. Adverse psychological consequences were subjectively observed by ASPN clinicians in 24 percent of women, exceeding any other category of complications. Management of all SABs in a hospital with D&C, instead of the management observed in this study, could add $145,000,000 per year to health care expenditures in the United States.