RANZCOG - instrumental vaginal delivery Flashcards
What is the incidence of vacuum and forceps assisted vaginal births in Australia and NZ?
10%
What are 3 non operative interventions that may reduce the need for instrumental delivery?
- continuous midwifery support during labour
- upright or lateral positions in 2nd stage
- use of oxytocinon
List 3 indications for assisted vaginal delivery
- suspected or anticipated fetal compromise
- delay in the 2nd stage of labour
- maternal effort contraindicated
What are the risks of a delayed 2nd stage of labour?
- increased chance of fetal compromise
- pelvic floor injury and sphincter dysfunction more likely
List the contraindications to instrumental delivery
- fetal bleeding disorders (e.g. alloimmune thrombocytopenia)
- predisposition to fracture e.g. osteogenesis imperfecta
- face presentation - vacuum contraindicated
- <34/40 CI for vacuum (between 34-36/40 unclear safety)
List the findings on abdominal and vaginal examination that would satisfy the requirements for instrumental vaginal birth
- Less than 1/5th palpable
- Cephalic
- cervix fully dilated, membranes ruptured
- exact position of head known
- caput and moulding and pelvis size considered
What are the steps required for preparation of mother for instrumental delivery?
- informed consent
- analgesia - regional ideally, pudendal acceptable in urgent delivery
- empty bladder - IDC removed or balloon deflated
- aseptic technique
List the preparation of staff required for an instrumental delivery
- knowledge and skill necessary from operator
- adequate facilities
- back up plan in case of failure to deliver (CS within 30 mins)
- senior obstetrician competent in performing mid cavity births should be present
- anticipation of shoulder dystocia, PPH
- personnel present that are trained in neonatal resuscitation
How is an outlet instrumental classified?
- fetal scalp visible without separating the labia
- fetal skull has reached the pelvic floor
- sagittal suture is in the OP diameter or right or left OA or posterior position (rotation does not exceed 45deg)
- fetal head is at or on the perineum
How would you classify a low instrumental delivery
- leading point of the skull (not caput) is at station +2 and not on the pelvic floor
- 2 subdivisions - rotation of 45 deg or less from the OA position, rotation of more than 45 deg including the OP position
How would you classify a mid cavity instrumental delivery?
fetal head is no more than 1/5th palpable per abdomen
leading point of the skull is above the station +2cm but not above the ischial spines
2 subdivisions - rotation of 45 deg or less from the OA position, rotation is more than 45 deg including the OP position
How would you classify a high cavity
- instrumental delivery not recommended in this setting
- 2/5th palpable abdominally
- Presenting part above the level of ischial spines
List 4 factors that are associated with failure of instrumental delivery?
- BMI >30
- EFW >4kg
- OP position
- Mid cavity or when 1/5 of fetal head palpable abdominally
What is the evidence behind performing an episiotomy for instrumental delivery?
In women having their first vaginal delivery an episiotomy
- results in 24% fewer OASIS when forceps used
- results in 16% fewer OASIS when ventouse used
Describe cup placement for vacuum extraction
- placement of cup at the flexion point
- flexion point = 6cm from anterior fontanelle, 3cm from posterior fontanelle
- in midline over the sagittal suture
enables flexion of the fetal head with traction improving chance of rotation of the head if necessary
What is the time frame recommended before bailing on vacuum extraction?
upper limit of 20 mins from application of cup
if birth not imminent after 15 mins consider CS
When should an operator consider reverting to CS during a trial of instrumental with vacuum?
- 20 mins max (at 15 mins consider)
- 3 pulls max
- 3 pop offs max
When compared with C/S what are the risks of rotation forceps delivery?
- small increased risk of traumatic intracranial haemorrhage
- small increased risk of cervical spine injury
List 5 fetal complications of instrumental delivery
- shoulder dystocia + complications
- subgaleal haemorrhage
- facial nerve palsy, retinal haemorrhage, corneal abrasion
- skull fracture +/- intracranial haemorrhage
- cervical spine injury
what is the difference in cephalhaematoma rates between vacuum vs forceps?
- forceps have a trend toward few cases of cephalhaematoma RR 0.64
What are the risks of forceps vs vacuum delivery?
- greater risk of 3rd and 4th degree tears
- greater risk of vaginal trauma
- greater risk of incontinence or altered continence
What is the RR of 3/4deg tear with forceps cf vacuum?
RR 1.9 (forceps vs vacuum)
What is the RR of vaginal trauma with forceps vs vacuum?
RR 2.5
what is the RR of incontinence with forceps vs ventouse delivery?
- RR 1.77
