The Nordic Obstetric Surveillance Study: A study of complete uterine rupture, abnormally invasive placenta, peripartum hysterectomy, and severe blood loss at delivery

Objective To assess the rates and characteristics of women with complete uterine rupture, abnormally invasive placenta, peripartum hysterectomy, and severe blood loss at delivery in the Nordic countries. Design Prospective, Nordic collaboration. Setting The Nordic Obstetric Surveillance Study (NOSS) collected cases of severe obstetric complications in the Nordic countries from April 2009 to August 2012. Sample and methods Cases were reported by clinicians at the Nordic maternity units and retrieved from medical birth registers, hospital discharge registers, and transfusion databases by using International Classification of Diseases, 10th revision codes on diagnoses and the Nordic Medico-Statistical Committee Classification of Surgical Procedure codes. Main outcome measures Rates of the studied complications and possible risk factors among parturients in the Nordic countries. Results The studied complications were reported in 1019 instances among 605 362 deliveries during the study period. The reported rate of severe blood loss at delivery was 11.6/10 000 deliveries, complete uterine rupture was 5.6/10 000 deliveries, abnormally invasive placenta was 4.6/10 000 deliveries, and peripartum hysterectomy was 3.5/10 000 deliveries. Of the women, 25% had two or more complications. Women with complications were more often >35 years old, overweight, with a higher parity, and a history of cesarean delivery compared with the total population. Conclusion The studied obstetric complications are rare. Uniform definitions and valid reporting are essential for international comparisons. The main risk factors include previous cesarean section. The detailed information collected in the NOSS database provides a basis for epidemiologic studies, audits, and educational activities.