Uterine rupture and VBAC Flashcards
What risk factor has the highest association with uterine rupture in a woman with a previous caesarean section?
- A Spontaneous onset of labour.
- B Severe pelvic girdle pain.
- C The use of oxytocin in labour.
- D Prostaglandin E2 induction of labour.
- E Women with systemic lupus erythematosus.
D The greatest risk factor for uterine rupture in a woman with a previous caesarean section is the use of prostaglandin to induce labour in the presence of an unfavourable cervix. This increases the risk of uterine rupture with an aOR of 3.92 (95% CI 1.00-15.33).
Ms B is 39 weeks’ gestation in her second pregnancy. Her first pregnancy was a term delivery, delivered 11 months previously by caesarean section at 5 cm dilated due to failure to progress. Ms B was induced due to FGR and has been on oxytocin for 4 hours and has made good progress. She is now 9 cm dilated when she develops severe constant lower abdominal pain over the area of her scar. The midwife looking after her labour records the fetal heart rate as 46 beats per minute and calls an emergency alert.
A What is the likely diagnosis?
B What risk factors does Ms B have for this complication?
C How would you manage this situation?
1 Ms B has likely ruptured her uterus due to the nature and location of pain (constant and severe worse above her scar) and the fetal bradycardia that has now occurred. Differential diagnosis includes fetal distress.
2 Ms B has had a previous caesarean section and has been induced due to FGR. The use of oxytocin also increased the risk of uterine rupture. Ms B has also had a short interpreg-nancy interval <12 months, which increases the risk of uterine rupture.
3 Management involves calling senior help (senior obstetrician, neonatal team, anaesthetic team), safe delivery of fetus and repair of the rupture. Delivery of the fetus is by safest quickest route. A vaginal examination should be performed and assessment for vaginal delivery made. If vaginal delivery is possible, then this should be performed and assessment made for examination under anaesthetic and/or laparotomy. If vaginal delivery is not possible, the patient should be transferred to the operating theatre for category 1 caesarean section, examination under anaesthetic and laparotomy.
How common is uterine rupture?
2 in 10,000 pregnancies affected overall
21 per 10,000 in VBAC
What are the risk factors for uterine rupture?
- previous myomectomy breaching the endometrial cavity
- 2 or more previous caesarean sections (x3)
- <12 months since last caesarean delivery (x3)
- labour induction and oxytocin use (x4)
What are the warning signs/presenting factors of uterine rupture?
- Maternal shock
- Fetal distress
- Inability to auscultate fetal heart
- Unable to palpate any presenting part on vaginal examination
- Severe sudden abdominal pain
What is the management of uterine rupture?
- Call for senior help
- ABCDE approach
- 2x large bore cannulae
- Urgent bloods for: FBC, clotting, G&S (if not done previously) and cross-match
- Transfuse blood as soon as possible
- Expedite delivery
- This may be vaginal if the woman is fully dilated and can be safely done
- Otherwise category 1 C-section
- Urgent laparotomy to examine and repair (or remove) the uterus
What steps can be taken to prevent uterine rupture?
- Reduce rates of primary caesarean section
- Avoid vaginal delivery in women with previous myomectomies where endometrial cavity was breached
- Caution when inducing VBACs
When is rupture most likely to occur during labour?
Usually in the late first stage of labour with induced or accelerated labour and in association with a large baby
What are the birth options for women with previous C-section?
- Vaginal birth after C-section (VBAC)
- Elective repeat C-section (ERCS) - if _>_2 previous C-sections this is the only option.
What are the relative and absolute contraindications for a VBAC?
RELATIVE:
- ≥2 previous C-sections
- Need for IOL
- Previous labour outcome suggestive of cephalopelvic disproportion
ABSOLUTE:
- Previous classical C-section
- Previous uterine rupture
- Other absolute contraindications to vaginal birth that apply irrespective of the presence or absence of a scar (e.g. placenta praevia)
Discuss VBAC.
- success rate and associated factors
- risks and complications
- benefits
Success rate = 72-75%
Factors associated with increased success:
- previous successful VBAC is the single best predictor of successful VBAC and has a success rate of 85-90%
- previous vaginal delivery,
- spontaneous onset of labour,
- normal size baby, vertex presentation
Risk of uterine rupture = 1 in 200 (increased to 1 in 100 with the use of syntocinon)
Benefits of:
- avoiding a further CS with its implications on future pregnancies
- increasing likelihood of success of future vaginal births
Discuss ERCS.
- risks
- benefits
Risk of another CS with its implications on future pregnancies including:
- risk of placenta praevia
- accreta in future pregnancies
- risk of pelvic adhesions complicating future abdominopelvic surgery
Benefits -
- avoids risk of uterine scar rupture
- avoids risk of requiring an emergency CS
How does a lower segment scar increase risk of uterine scar rupture?
1 in 200 in those who labour sponatenously with lower segment scar
2-3 in 200 (i.e. x2-3) in those who labour sponatneously with an upper segment scar
NB: benefits of upper segment incision is less blodo loss, better healing and lower risk of future dehiscence (scar separation).
What are the fetal and maternal complications of uterine rupture?
Maternal:
- shock
- need for blood transfusion
- operative repair
- possible hysterectomy
Fetal:
- hypoxia
- permanent neurological injury
- perinatal death
