Objective To investigate the early diagnosis and treatment of cesarean scar pregnancy(CSP).Methods Clinical data of 28 patients with CSP in Peking Union Medical College Hospital from January 1994 to April 2007,including age,interval from the last cesarean delivery to diagnosis,clinical presentation,location of the lesion,process of diagnosis and treatment,outcome,and follow-up,were retrospectively analyzed.Results CSP constituted 1.05% of all ectopic pregnancies,and the ratio of CSP to pregnancy was 1∶1221.The mean age of the group was 31.4 years.Twenty-six women had only one prior cesarean delivery.The interval from the last cesarean delivery to diagnosis ranged from 4 months to 15 years.The most common presenting symptoms of CSP were amenorrhoea and vaginal bleeding.Seventeen cases were misdiagnosed as early intrauterine pregnancies and 2 were misdiagnosed as gestational trophoblastic tumor.The other 9 were diagnosed definitely before treatment.The diagnosis was made based on cesarean delivery history,gynecologic examination,ultrasound,and magnetic resonance imaging(MRI).The treatment of CSP included systemic or local methotrexate administration,conservative surgery,and hysterectomy.The conservative treatment was successful in 24 cases.All of the 28 women were cured through individual therapies.Conclusions CSP is rare and usually misdiagnosed as other diseases.Ultrasound is valuable for diagnosing CSP,and MRI can be used as an adjunct to ultrasound scan.Early diagnosis offers the options of conservative treatment and greatly improves the outcome of patients.Individual therapy is strongly recommended. Objective To investigate the early diagnosis and treatment of cesarean scar pregnancy (CSP). Methods Clinical data of 28 patients with CSP in Peking Union Medical College Hospital from January 1994 to April 2007, including age, interval from the last cesarean delivery to diagnosis, clinical presentation, location of the lesion, process of diagnosis and treatment, outcome, and follow-up, were retrospectively analyzed. Results CSP composed 1.05% of all ectopic pregnancies, and the ratio of CSP to pregnancy was 1:1221. the group was 31.4 years.Twenty-six women had only one prior cesarean delivery. The interval from the last cesarean delivery to diagnosis ranged from 4 months to 15 years.The most common presenting symptoms of CSP were amenorrhoea and vaginal bleeding. misdiagnosed as early intrauterine pregnancies and 2 were misdiagnosed as gestational trophoblastic tumor. the other 9 were diagnosed definitely before treatment.The diagnosis was made based on cesar ean delivery history, gynecologic examination, ultrasound, and magnetic resonance imaging (MRI). The treatment of CSP included systemic or local methotrexate administration, conservative surgery, and hysterectomy. conservative treatment was successful in 24 cases. All of the 28 women were cured through individual therapies. Conclusions CSP is rare and usually misdiagnosed as other diseases. Ultrasound is valuable for diagnosing CSP, and MRI can be used as an adjunct to ultrasound scan. Early diagnosis offers the options of conservative treatment and greatly improves the outcome of patients. Individual therapy is strongly recommended.