How Predictive is CTG of
Scar Rupture in VBAC?
Varsha Jain and Ann Daly
Birmingham Women’s Hospital
Aims and Objectives
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Review current evidence re: CTG and
scar rupture in VBAC
Critically appraise a study
The clinical question
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Does continuous monitoring with CTG
help us to identify scar rupture in vaginal
birth after section?
Question identified from a morning CTG
meeting
Literature Search
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Sources:
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Cochrane
Pubmed
MIDIRS
Search terms:
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Cardiotocography (MeSH)
Uterine rupture (MeSH)
Guidelines
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BWH guidelines state:
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Very low risk of scar rupture in planned VBAC
(0.5%)
Features to identify scar rupture:
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Abnormal CTG
Severe abdominal pain, esp in between contractions
Chest pain/SOB/shoulder tip pain
Acute onset scar tenderness
Cessation of previously efficient uterine activity
Maternal tachycardia, hypotension. Shock
Loss of station of presenting part
Vaginal bleeding
Category 1 section & incident form
Risk of augmentation
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Decision to induce should be a consultant
led decision
Risk of scar rupture in
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Induced – 102 in 100,000 (1.02%)
Augmented – 87 in 100,000 (0.87%)
Spontaneous – 36 in 100,000 (0.36%)
Literature Search Results
Three papers identified
1.
Diagnostic potential of CTG for silent uterine rupture
Acta Obstet Gynecol Scand 1989 68 (7) 653-6
(3 patients, CTG done, but uterine rupture not identified until
section)
2.
A ten year review of uterine rupture in modern obstetric practice
Ann Acad Med Singapore 1995 24 (6) 830-5
3.
Symptoms and Signs with scar rupture – value of uterine activity
measurements
Aust N Z J Obstet Gynaecol 1992 32 (3) 208-12
Papers selected
2.
A ten year review of uterine rupture in modern
obstetric practice Ann Acad Med Singapore 1995 24 (6)
830-5
3.
Symptoms and Signs with scar rupture – value of
uterine activity measurements Aust N Z J Obstet Gynaecol
1992 32 (3) 208-12
A ten year review of uterine rupture in
modern obstetric practice
Study details
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Retrospective analysis using theatre records at Kerbau
Hospital, Singapore
1983 – 1992
26 cases of uterine rupture or scar dehiscence
Of the 26, 20 cases had previous LSCS
Most common presentation (25%) was abnormal CTG
(variable or late decelerations or early decelerations
with other signs of fetal compromise eg m/s liquor)
Symptoms and Signs with scar rupture –
value of uterine activity measurements
Study details
 National University Hospital Singapore
 1985-1990
 24,182 total deliveries
 CS rate 12.5% (3026)
 Previous LSCS 4.2% (1018)
 Of this 70.9% (722) had only one
previous CS and trial of labour
Study Details cont.
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Of the women who had a trial of labour 70%
(506) delivered vaginally
4 cases of incomplete scar rupture
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5 cases of complete scar rupture
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Incomplete scar rupture where uterine myometrium was
breached but peritoneum remained intact
Complete scar rupture where both uterine myometrium and
peritoneum were breached
CTG appearances of fetal distress or sudden
decrease in uterine activity
Study Findings
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No maternal death or severe morbidity
(one bladder tear)
One fresh stillbirth (hydrocephalus)
One neonatal death
All 9 cases had oxytocin infusion
Critical appraisal (CASP)
Was the study type appropriate to answer
the question?
Both studies were retrospective analysis
of labour records – yes this is an
appropriate study to answer this type of
question
Critical appraisal
Were confounding factors accounted for?
 Parity
 Number of previous C/S
 Previous vaginal deliveries
 Size of baby
 Use of oxytocin
 Duration of labour
 Age of mother?
 Ethnicity?
 Any more ….
Will the results help us manage our
patients?
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Useful to look at study results to see how
patients can present
Useful to see types of CTG changes
Not so useful as continuous CTG will still
be needed
Practice in this hospital will not change
based on these studies – a pre-existing
BWH thorough guideline
Conclusion
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Review of current guidelines in relation to
VBAC and scar rupture
Presented two studies – total of 29 cases
CTG monitoring is needed as can show
helpful signs
Need to consider full clinical picture
Need more recent research and larger
study numbers