Interobserver agreement in analysis of cardiotocograms recorded during trial of labor after cesarean

Introduction: To examine interobserver agreement in intrapartum cardiotocography (CTG)
classification in women undergoing trial of labor after a cesarean section (TOLAC) at term with
or without complete uterine rupture.
Materials and methods: Nineteen blinded and independent Danish obstetricians assessed CTG
tracings from 47 women (174 individual pages) with a complete uterine rupture during TOLAC
and 37 women (133 individual pages) with no uterine rupture during TOLAC. Individual pages
with CTG tracings lasting at least 20 min were evaluated by three different assessors and
counted as an individual case. The tracings were analyzed according to the modified version of
the Federation of Gynaecology and Obstetrics (FIGO) guidelines elaborated for the use of STAN
(ST-analysis). Occurrence of defined abnormalities was recorded and the tracings were classified
as normal, suspicious, pathological, or preterminal. The interobserver agreement was evaluated
using Fleiss’ kappa.
Results: Agreement on classification of a preterminal CTG was almost perfect. The interobserver
agreement on normal, suspicious or pathological CTG was moderate to substantial. Regarding
the presence of severe variable decelerations, the agreement was moderate. No statistical
difference was found in the interobserver agreement between classification of tracings from
women undergoing TOLAC with and without complete uterine rupture.
Conclusions: The interobserver agreement on classification of CTG tracings from high-risk
deliveries during TOLAC is best for assessment of a preterminal CTG and the poorest for the
identification of severe variable decelerations.