How Predictive is CTG of Scar Rupture in VBAC?

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How Predictive is CTG of Scar Rupture in VBAC?

• Varsha Jain and Ann Daly
• Birmingham Womens Hospital

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Aims and Objectives

• Review current evidence re CTG and scar rupture
  in VBAC
• Critically appraise a study

3
The clinical question

• Does continuous monitoring with CTG help us to
  identify scar rupture in vaginal birth after
  section?
• Question identified from a morning CTG meeting

4
Literature Search

• Sources
• Cochrane
• Pubmed
• MIDIRS
• Search terms
• Cardiotocography (MeSH)
• Uterine rupture (MeSH)

5
Guidelines

• BWH guidelines state
• Very low risk of scar rupture in planned VBAC
  (0.5)
• Features to identify scar rupture
• 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

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Risk of augmentation

• Decision to induce should be a consultant led
  decision
• Risk of scar rupture in
• Induced 102 in 100,000 (1.02)
• Augmented 87 in 100,000 (0.87)
• Spontaneous 36 in 100,000 (0.36)

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Literature Search Results

• Three papers identified
• 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

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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

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A ten year review of uterine rupture in modern
obstetric practice

• Study details
• 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)

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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

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Study Details cont.

• Of the women who had a trial of labour 70 (506)
  delivered vaginally
• 4 cases of incomplete scar rupture
• Incomplete scar rupture where uterine myometrium
  was breached but peritoneum remained intact
• 5 cases of complete scar rupture
• Complete scar rupture where both uterine
  myometrium and peritoneum were breached
• CTG appearances of fetal distress or sudden
  decrease in uterine activity

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Study Findings

• No maternal death or severe morbidity (one
  bladder tear)
• One fresh stillbirth (hydrocephalus)
• One neonatal death
• All 9 cases had oxytocin infusion

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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

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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 .

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Will the results help us manage our patients?

• 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

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Conclusion

• 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