Design and study population
This was a descriptive, retrospective, population-based study looking at
the outcomes of new pregnancies in mothers with previous complete
uterine rupture. Data were extracted from all births in Norway
registered from 1967-2011 (N=2 455 797). Two registries were used: the
Medical Birth Registry of Norway (MBRN) and the Patient Administration
System (PAS). The MBRN contains information on all births in Norway
after 16 weeks of gestation. Midwives attending a birth fill out and
send a standardized MBRN form within 7 days after delivery. The PAS is a
local registry at each maternity unit that maintains records of all
inpatient diagnoses. All ruptures were identified using international
diagnostic codes. In the MBRN, the internal code for uterine rupture was
71 prior to 1999; from 1999 to the present, the diagnostic codes are
O710 and O711 based on the 10th revision of the International
Classification of Diseases
(ICD).8In the PAS, uterine rupture was identified by the ICD8 code
(1967–1978),9ICD9 codes 6650 and 6651
(1979–1998),10and ICD10 codes O710 and O711
(1999–present).8These codes do not specify the rupture type (complete or partial), which
was identified in the medical records. Complete rupture was defined as
the rupture of all uterine wall layers, including the serosa and
amniotic membranes, and partial rupture as rupture of the uterine wall,
sparing the serosa or membranes. All births associated with a uterine
rupture were identified by the first author, who visited maternity units
in Norway and reviewed maternal medical records. Those with complete
uterine ruptures were followed (n=274).
The study population was mothers with new pregnancies and child births
after previous complete uterine rupture (n= 72). We studied the
characteristics of previous complete ruptures and the rate of repeat
ruptures and outcomes of these pregnancies.
The Regional Ethics Committee (2010/1609–4) and the Data Inspectorate
of Norway approved the study. The South-Eastern Norway Regional Health
Authority funded the study of uterine rupture as a post-PhD project for
the lead author.