DOES AN ‘AFTER HOURS’ DELIVERY AFFECT THE RATE OF THIRD & FOURTH DEGREE
TEARS? A RETROSPECTIVE COHORT STUDY AT A REGIONAL AUSTRALIAN HOSPITAL
OVER 3 YEARS
Abstract
Objective: Does an ‘after hours’ delivery affects the rate of
third and fourth degree tears (Obstetric Anal Sphincter Injuries, OASIS)
Design: a single -centre retrospective cohort study
Setting: A major regional Australian hospital
Population: All cephalic vaginal deliveries at 37+ weeks over a
3-year period. Exclusions: previous/planned Caesarean section,
prematurity, multiple pregnancies, non-cephalic presentations and models
of care other than mainstream consultant-led care. Methods:
Data collected was age, parity, gestation, body mass index, induction of
labour, use of oxytocin, second stage duration, mode of delivery,
perineal trauma, episiotomy and birth weight. Main Outcome
Measures: Compare the rates and risk factors of OASIS between
deliveries occurring “in hours” (8am-8pm weekdays) and “after hours”
(8pm-8am, weekends and public holidays) Results: 2404 patients
were included. 57.4% of deliveries occurred ‘after hours’. The overall
rate of OASIS was 3.12% with no statistical difference between ‘in
hours (3.22%) and ‘out of hours’ (3.04%), p=0.8. More primigravid
deliveries and spontaneous onset of labours occurred ‘out of hours’
(both p<0.001). More multigravid deliveries, labours requiring
oxytocin and prolonged second stage occurred ‘in
hours’(p=<0.01). No statistical significance was noted for
epidural analgesia (34.0% vs 34.3%, P=0.85), spontaneous vaginal birth
(90.4% vs 90.1%, P=0.81), operative vaginal birth (9.6% vs 9.9%,
P=0.81) and episiotomy use (17.2% vs 18.4%, P=0.41).
Conclusions: No statically significant difference was noted in
the rate of OASIS ‘in hours’ and ‘out of hours’ in our centre.