Instrumental Delivery Flashcards
Where should the ventouse cup be placed?
Flexion point
6cm from the anterior fontanelle and 3cm from the posterior fontanelle in the midline over the sagittal suture
What is the failure rate of rigid Ventouse cup compared to the soft cup?
Rigid cup = 9.5%
Soft cup = 14.8%
What is the rate of scalp injuries with rigid cup and soft cup?
Rigid cup = 24%
Soft cup = 13%
What is the upper limit of time allowed to have the ventouse on?
Upper limit of 20 minutes (as per RANZOG guideline).
If birth not imminent after 15 minutes, evaluate
How many times can the cup detach before you should abandon?
2 (RCOG)
3 (RANZCOG)
What are the risks of rotational forceps?
(2, fetal)
Traumatic intracranial haemorrhage
Cervical spine injury
If someone has an instrumental delivery in their first pregnancy, what is the chance that they will have a NVD in a subsequent pregnancy?
90% if in room
80% if in OT
What antibiotic should be given after instrumental delivery?
Single dose IV Augmentin
Significantly reduces confirmed or suspected maternal infection compared to placebo
ANODE
What is the effect of RML episiotomy on OASIS in instrumental deliveries?
Ventouse: 16% fewer OASI
Forceps: 24% fewer OASI
NNT 19
With instrumental deliveries, higher rates of failure are associated with what risk factors?
Maternal BMI > 30
EFW > 4kg / clinically big baby
OP position
Mid pelvic birth or when 1/5 head palpable per abdomen
RCOG:
Short maternal stature
HC > 95th centile
Ventouse should not be used prior to what gestation?
34/40 (RANZCOG)
“The safety of ventouse between 34 and 36/40 is unknown and should be used with caution”
32/40 (RCOG)
What is the risk of cup detachment?
Rapid decompression
may result in vessel damage i.e. rupture of emissary veins through tractional and rotational forces
and predispose to subgaleal haemorrhage
What is the risk of OASIS injury with ventouse vs forceps?
Ventouse: 1-4:100
Forceps: 8-12:100
(RCOG Consent form)
What is the risk of extensive or significant vaginal / vulval tear with ventouse vs forceps?
Ventouse 1:10
Forceps 1:5
(RCOG Consent form)
What is the risk of subgaleal haematoma with ventouse?
1:300 (RANZCOG)
3-6:1000
RCOG consent form
What is the risk of intracranial haemorrhage with instrumental delivery?
5-15:10,000
RCOG consent form
What is the risk of PPH with instrumental delivery?
1-4:10
RCOG consent form
What is the risk of cephalhaematoma with ventouse?
1-2:100
RCOG consent form
What is the risk of facial or scalp lacerations with instrumental delivery?
1:10
RCOG consent form
What is the risk of neonatal jaundice / hyperbilirubinaemia following instrumental delivery?
5-15:100
RCOG consent form
What is the risk of retinal haemorrhage with instrumental delivery?
17-38:100
Very common
(RCOG consent form)
What are three indications for an instrumental delivery
- Suspected or anticipated fetal compromise
- Delay in the second stage of labour
- fetal descent may precipitate cord compression
- intense uterine activity and expulsion maternal efforts may reduce placental blood flow to the extent that the fetus is compromised
- maternal exhaustion
- pelvic floor injury - Maternal effort is contraindicated
- Cerebral aneurysm
- Cardiac failure
- Severe hypertension
- Severe retinopathy
- Risk of aortic dissection
What are contraindications to ventouse delivery?
Fetal bleeding disroders e.g. alloimmune thrombocytopenia
Fetal predisposition to fracture e.g. osteogenesis imperfect a
Face presentation
Gestation <34/40
Relative
- 34-36/40
- Prior FBS
What are the pre-requisites that need to be met BEFORE proceeding with an instrumental birth?
< 1/5 head palpable abdominally
Vertex presentation
Cervix fully dilated and membranes ruptured
Certain about position to facilitate appropriate application of instrument.
- May need USS to confirm this
Assessment of caput and moulding
Pelvis deemed adequate
What are the fetal / neonatal complications of instrumental delivery?
Shoulder dystocia
Subaponeurotic / subgaleal haemorrhage
Facial nerve palsy, corneal abrasion, retinal haemorrhage
Facial or scalp lacerations
Skull fracture
Intracranial haemorrhage
Cervical spinal injury
Jaundice or hyperbilirubinaemia
What are the maternal complications of instrumental delivery?
PPH
Vaginal trauma
Urinary tract injury
Damage to pelvic floor and anal sphincter
Which instrument is less likely to fail?
Forceps
RR 0.65
Which instrument is associated with fewer cephalohaematomas?
Forceps RR 0.64
Which instrument is associated with fewer retinal haemorrhages?
Forceps 0.6
Which instrument is associated with fewer cases of jaundice?
Forceps
RR 0.8
Which instrument is associated with fewer cases of shoulder dystocia?
Forceps
RR 0.4
Which instrument is less likely to be associated with OASIS injuries?
Ventouse
RR for forceps 1.9
Which instrument is less likely to be associated with vaginal trauma?
Ventouse
RR for forceps is 2.5
Which instrument is less likely to be associated with incontinence / altered continence?
Ventouse
RR for forceps 1.8
What are the risks of sequential instrumental delivery?
Increased risk of trauma to the fetus and the mother, including OASI injury
What is the fetal and maternal morbidity associated with CS at full dilatation with deep head?
Maternal - PPH, transfusion, lower segment tear, Cystotomy, hysterectomy, ICU admission
Fetal - neonatal acidosis, intracranial haemorrhage, need for resuscitation
What are 4 important parts of the after-care following an instrumental delivery?
- Antibiotics - Augmentin as per ANODE trial
- Be alert for voiding dysfunction
- increased risk of urinary retention
- if had spinal / epidural top up in OT, should have IDC in for 12 hours
- careful observation of postpartum voiding function and the insertion of an IDC may be required to prevent bladder over-distension and long-term bladder dysfunction - Pelvic Floor Rehab
- physiotherapist led intervention reduces urinary incontinence - VTE risk assessment
Additional: Vit K
What are the recommended vacuum pressures for a ventouse delivery?
500-600mmHg
RANZCOG guideline
How should traction be applied in a ventouse delivery?
Steady
Only with contractions
Only with maternal efforts
Direction should follow the axis of the pelvic curve
Adequate descent should be verified with the free hand during each pull
What is less likely to fail between rotational forceps and rotational ventouse?
Rotational forceps less likely to fail
RR 0.3
Also less likely to cause neonatal trauma RR 0.6
What are the guidelines for rotational forceps in the RANZCOG Guideline?
Head must be negated
Regional block
Adequate experience or supervision
Rotation of the fetal head should only be attempted BETWEEN contractions
Low threshold for abandoning the procedure and resorting to CS
When should rotational forceps be discontinued?
Forceps cannot be applied easily
Handles do not approximate easily
Rotation is not easily achieved with gentle pressure
Lack of progressive descent with moderate traction
If birth is not imminent following three pulls
What are 5 steps to reduce the need for instrumental delivery?
- Continuous midwifery support in labour
- Upright or lateral positions in the second stage of labour if no epidural OR lateral lying down positions if has epidural.
- Use of Oxytocin in 2nd stage for primip
- Passive descent
- meta-analysis: primip less likely to require rotational intervention when pushing was delayed for up to 2 hours or until they had a strong urge to push - Manual rotation
What are the success rates of manual rotation?
When successful, what effect do they have?
76-89%
Significantly
Reduces the need for CS
Increases SVD and instrumental vaginal birth
What are 5 risk factors for subgaleal haemorrhage?
Nulliparity
5 minute APGAR < 7
Cup marks on Sagittarius suture, suggestive of paramedian application
Leading edge of the vacuum cup too close (<3cm) to anterior fontanelle, causing de flexion
Failed vacuum extraction
Among babies admitted to the NICU with SGH, what is the mortality?
12-25%
What % blood volume can a neonate lose into a subgaleal haemorrhage?
And why?
Large potential space
Between the epicranial aponeurosis and the periosteum
If allergic to Augmentin, what antibiotic should be given following instrumental delivery, as per RANZCOG?
Cefazolin 2g
Clindamycin 600mg
What is the definition of a subgaleal haemorrhage?
Bleeding into potential space between the epicranial aponeurosis and periosteum.
What are subgaleal haemorrhages so dangerous?
Potential space can contain 250 mL of blood which equates to 50-70% of a neonates’s total blood volume.
Can lead to hypovolaemic shock, anaemia, coagulopathy and death.
What is the neonatal mortality rate associated with subgaleal haemorrhage?
12-25%
What is the definition of caput succedaneum?
Serosanguinous fluid accumulation that is extra-aponeurotic.
Can cross suture lines.
Caused by pressure of head during birth and labour.
What is the definition of cephalohaematoma?
Bleeding between the periosteum and underlying skull.
Cannot cross suture lines.
Soft-fluctuant localised swelling with well-defined outline.
What % of subgaleal haemorrhage occurs secondary to ventouse delivery?
60-90%
When monitoring for subgaleal haemorrhage with serial HC measurements, how does increase in HC correlate with volume of blood loss?
1 cm increase in HC equates to around 38 mL of blood loss.
What are risk factors for a subgaleal haemorrhage?
- Nullip
- Paramedian placement
- Deflexing placeme nt
- Failed ventouse
- 5 min Apgar <=7
