How should success be defined when attempting medical resolution of first-trimester missed abortion?

Abstract Objectives: There is currently no consensus on how success should be defined after medical management of first-trimester missed abortion. The aim of this study was to determine the transvaginal ultrasound criterion associated with highest success rate and, at the same time, lowest long-term complications. Design: Prospective observational study of consecutively enrolled patients. Setting: A tertiary care university hospital in northern Portugal. Participants : Forty-four women submitted to medical management of first-trimester missed abortion using a regimen of vaginal misoprostol, with histologically confirmed conception products passed vaginally. A transvaginal ultrasound scan was performed by an experienced sonographer in the morning after treatment, to characterise uterine content. Patients were provided with a chart for daily registration of axillary temperature, vaginal bleeding and lower abdominal pain. Transvaginal ultrasound was repeated 2–3 weeks later, and again after the following menses. Main outcome measures: Success rates of medical management when post-treatment transvaginal ultrasound criteria for subsequent expectant management were: absence of intra-uterine sac, largest anteroposterior diameter of hyperechogenic content, and maximum area of hyperechogenic intra-uterine content in a sagittal view. Self-reported duration of vaginal bleeding and abdominal pain after medical treatment. Results: Success rate was 86% (38/44) when absence of gestational sac on the 12 h transvaginal ultrasound was used as the main criterion for subsequent expectant management and there was no need for further intervention. The success rate using the ultrasound criterion anteroposterior diameter ≤15 mm was 51% (22/43), and with maximum sagittal plane area under 7.5 cm 2 , 72% (31/43). Mean duration of vaginal haemorrhage was 9 days (minimum 2 days, maximum 14 days) and of lower abdominal pain 6 days (minimum 0 days, maximum 14 days). No patient recorded an axillary temperature exceeding 37 °C. No apparent relationship between the size of ultrasound-estimated intra-uterine content and duration of symptoms was observed. Conclusions: Absence of gestational sac on transvaginal ultrasound should be the criterion used to document success after medical management of first-trimester missed abortion, as it is associated with the highest short and long-term success rates, as well as mild and self-limited symptoms in the days following treatment.