Labour Flashcards
What shape is the posterior fontanelle?
Triangle
What shape is the anterior fontanelle?
Diamond
What is the ideal cephalic presentation of the fetal head during labour?
Occipito-anterior
What proportion of pregnancies have to be induced?
1 in 5
What is an induction of labour?
Labour is initiated by the use of medications to ripen cervix usually followed by Artificial rupture of amniotic membranes
What is an amniotomy?
The intentional rupture of the amniotic sac
What are the indications for the induction of labour?
- hypertensive disorders
- Maternal diabetes
- Prolonged pregnancy
- Twin pregnancy
- Prelabour rupture of membranes
- Foetal growth restriction or macro Sonia
- Maternal request in exceptional circumstances
- Previous still birth or interosseous death
- Post-dated uncomplicated pregnancy
What are the contraindications for induction of pregnancy?
- malpresentation
- Placenta praevia/vasa praevia
- Prolapsed umbilical cord
- Foetal distress
- Anatomical abnormalities e.g pelvic tumour
What is the Bishop’s score used for?
Used to clinically assess the cervix. The higher the score, the more progressive change there is in the cervix and indication that induction is likely to be successful.
What aspects of the cervix are assessed in the Bishop Score?
Position Consistency Effacement Dilation Station
What medications are used in the induction of labour?
• topical prostaglandin analogues e.g misoprostol
- encourage cervical dilutions and effacement
- alternative is balloon catheter- favourable over prostaglandins
• IV synthetic oxytocin e.gsyntocinon
- initiates uterine contractions
• require CTG monitoring
What are the complications for the induction of labour?
- uterine hypertonicity
- Foetal distress
- Adverse effect of drugs (hypotension, hyponatraemia)
- Failed induction
- Caesarean section
- Ruptured uterus
What is the process for the induction of labour?
Once cervix has dilated and effaced, an amniotomy can be performed. A bishop score of 7 or more is considered favourable for amniotomy.
Once amniotomy is performed, IV oxytocin can be used to achieve adequate contractions (unless contractions spontaneously start)
Aim for 4-5 contractions in 10 mins
What is meant by effacement of the cervix?
The cervix stretches and gets thinner
Name common Intrapartum complications. (Powers, passage and passenger)
- inadequate uterine activity
- cephalopelvic disproportion (CPD)
- Other reasons for obstruction
- malposition
- malpresentation
Fetal distress
How is progress in labour evaluated?
By a combination of abdominal and vaginal examinations to determine:
- cervical effacement
- cervical dilatation
- descent of the fetal head through the maternal pelvis
What is suboptimal progress in labour defined as?
Less than 0.5cm per hour for primigravid women
Less than 1cm per hour for porous women
How is inadequate uterine activity managed?
IV synthetic oxytocin increases strength and dilatation of the contractions.
Exclude an obstructed labour
What is cephalopelvic disproportion?
The fetal head is in the correct position for labour but it is too large to negotiate maternal pelvis to be delivered.
Genuine CPD is very rare.
What is the cause of relative CPD?
If there is malposition and the fetal head is in a suboptimal position for labour.
What are common causes of obstruction in labour?
Placenta praevia
Fetal anomaly
Fibroids
What is malposition?
Involves the fetal head being in a suboptimal position for labour: occipito-posterior and occipito- transverse
What are the main causes of fetal distress?
Hypoxia, infection, cord prolapse, placental abruption and vasa praevia.
How is a fetus monitored in labour?
Intermittent auscultation of the heart
Cardiotocography
Fetal blood sampling
Fetal ECG
How is a fetal blood sample take during labour?
Speculum used to take fetal scalp blood sample. Need to be 4cm dilated to do this.
What does a fetal blood sample allow us to measure?
- pH and base excess
- lactic acid
What is a retained placenta?
Placenta is not delivered within 30 minutes of the birth of the baby. Can lead to severe infection or blood loss.
What causes a retained placenta?
Contractions are not strong enough to expel placenta.
Cervix may close and trap the placenta inside the uterus.
What is the management of a retained uterus?
Injection of Syntocinon (synthetic oxytocin). Helps to deliver placenta and reduces risk of postpartum bleeding. Doctor or midwife may pull cord out.
What is a cord prolapse?
The umbilical cord slips through the cervix and into the vagina after the waters break but before the baby descends into the birth canal.
What are the risk factors for a prolapsed cord?
- breech presentation
- unstable lie
- artificial lie
- artificial rupture of membranes
- polyhydraminos: excessive amniotic fluid around fetus
- prematurity
What is an occult (incomplete) cord prolapse?
The umbilical cord descends alongside the presenting part, but not beyond it
What is an overt (complete) cord prolapse?
The umbilical cord descends past the presenting part and is lower than the presenting part in pelvis.
What is the management of a cord prolapse?
Avoid handling th cord to reduce vasospasm. Manually elevate the presenting part by lifting the presenting part off the cord by vaginal digital examination. Encourage into left lateral position. Delivery is usually via emergency Caesarean section.
How does cord prolapse result in fetal distress?
- lack of oxygen
What is shoulder dystocia?
A birth injury. One shoulder becomes stuck in pelvis. Normal traction on the fetal head does not lead to delivery of the shoulders.
What are the maternal complications of shoulder dystocia?
Damage to bladder, anal sphincter and rectum
Postpartum haemorrhage
What is the management of shoulder dystocia?
Call for help. Evaluate for episiotomy Legs (Mcroberts postion) Suprapubic pressure. Internal rotation Remove the posterior arm Roll patient onto all fours
What are the tissue causes of PPH?
Retained placenta
Placenta accreta
Retained products of conception
What are the tone causes of PPH?
Placenta praevia
Over distension of the uterus: multiple pregnancy, polyhydramnios, macrosomia
Uterine relaxants
Previous PPH
What are the trauma causes of PPH?
Caesarean section
Episiotomy
Macrosomia
What are the thrombin causes of PPH?
- pre-eclmapsia
- placental abruption
- pyrexia in labour
- bleeding disorders: haemophilia, anticoagulation, Von willebrand disease
What are the types of PPH?
Primary: 99%. In first 24hrs after delivery >500ml blood (common: 1/20 women) severe haemorrhage >2000ml (rare)
Secondary: >24hrs up to 6 weeks post delivery
What is the management of PPH?
Call for help ABCDE Empty bladder Rub up uterine fundus by massaging above the umbilicus Medications: - oxytocin slow IV injection - ergometrine 0.5mg slow IV injection - Oxytocin infusion Tranexamic acid 1g IV Carboprost 0.25mg im Surgical: -Intrauterine ballon tamponade -Interventional radiology -B-lynch suture -Hysterectomy Fluid replacement
Describe the two incisions used in Caesarean section.
Lower uterine segment incision
Classical: longitudinal incision (rare)
What are the indications for a Caesarean section?
- foetal distress
- Failure to progress in labour
- Failed induction of labour
- Malpresentaiton
- Severe pre-eclampsia
- Placenta praevia
- Twin pregnancy with a non-cephalon presenting twin
- Repeat Caesarean section
What are the categories of Caesarean section?
- emergency: immediate threat to life of women or foetus (within 30 minutes)
- Urgent: maternal or foetal compromise but not immediately life threatening (within 90 minutes)
- Scheduled: no time limit, requiring early delivery but no compromise
- Elective: no time limit: at a time to suit woman and maternity team
When is a CTG done during labour?
Any abnormalities or Intrapartum complications
- induction of labour
- Post-maturity (>42w) or mrematurity (<37w)
- Multiple pregnancy
- Underlying maternal health conditions: cardiac, diabetes, hypertension, pre-eclampsia
- Ante-argument or Intrapartum haemorrhage
- Pyrexia
- Abnormal or Intrapartum haemorrhage
- Abnormal lie, small for gestational age
- Epidural anaesthesia
- Abnormalities noted on intermittent auscultation
What key physiological changes must occur to allow for expulsion of the fetus during labour?
- Cervix softens
- Myometrial tone changes to allow for coordinated contractions
- Progesterone decreases whilst oxytocin and prostaglandins increase to allow labour to initiate
What are Braxton Hicks contractions?
- Tightening and relaxing of the uterus during pregnancy. They are not painful but are uncomfortable.
- Typically not felt until the second or third trimester. They do not indicate that labour has begun.
What happens in stage 1 of labour?
- Begins with regular contractions. Progressively more rhythmic, longer and stronger.
- Typically every 10-15mins increasing every 2-3 mins
- Cervix will efface (shorten) and dilate to 10cm
What happens in stage 2 of labour?
- Starts at full dilation and ends with delivery of the baby
- Usually heralded by a strong urge to push
- If vertex is visible- prepare toe deliver in department
What happens in stage 3 of labour?
- Delivery of Placenta
- Usually within 5-10mins but can take up to an hour
- Generally allow to happen spontaneously
What are the key stages of normal labour?
- Descent
- Engagement
- Neck Flexion
- Internal Rotation
- Crowning
- Extension of the Presenting Part
- Restitution
- External Rotation
- Lateral Flexion
What happens in the descent stage of labour?
- Fetus descends into pelvis. In the primigravida this is likely to occur from 38 weeks gestation onwards, in a multigravida woman, this may not occur until labour is established.
- As the head descends, it moves towards the pelvic brim in either the left or right occipito-transverse position (this means the occiput can be facing the left side or right side of the mother’s pelvis).
What allows descent of the fetus to occur?
- Uterine contraction
- Amniotic fluid pressure
- Abdominal muscle contraction
What encourages descent of the fetus into the pelvis to occur?
- Increased abdominal muscle tone
- Braxton hicks in the late stages of pregnancy
- Fundal dominance of the uterine contractions during labour
- Increased frequency and strength of contractions during labour
Describe the engagement stage of labour.
the widest part of the fetal head successfully negotiating its way down deep into the maternal pelvis
as the head engages, the head moves towards the pelvic brim in either the left or right occipital transverse position
What happens in the flexion stage of labour?
- As the fetus descends through the pelvis, fundal dominance of uterine contraction exerts pressure down the fetal spine towards the occiput, forcing the occiput to come into contact with the pelvic floor. When this occurs the fetal neck flexes (chin to chest) allowing the circumference of the fetal head to reduce to sub-occipitobregmatic (9.5cm).
- In this position, the fetal skull has a smaller diameter which assists passage through the pelvis.
What is the internal rotation stage of labour?
• The pelvic floor has a gutter shape with a forward and downward slope, encouraging the fetal head to rotate from the left or right occipito-transverse position a total of 90-degrees, to an occipital-anterior (occiput facing forward) position, to lie under the subpubic arch.
• With each maternal contraction, the fetal head pushes down on the pelvic floor. Following each contraction, a rebound effect supports a small degree of rotation. Regular contractions eventually lead to the fetal head completing the 90-degree turn.
Commonly completed by the start of the second stage of labour
Describe the crowning stage of labour.
- When the widest diameter of the fetal head successfully negotiates through the narrowest part of the maternal bony pelvis, the fetal head is considered to be ‘crowning’.
- This is clinically evident when the head, visible at the vulva, no longer retreats between contractions. Complete delivery of the head is now imminent and often the woman, who has been pushing, is encouraged to pant so that the head is born with control.
Describe the extension of the presenting part during labour.
• The occiput slips beneath the suprapubic arch allowing the head to extend. The fetal head is now born and will be facing the maternal back with its occiput anterior.
Describe the restitution stage of labour.
- The occiput slips beneath the suprapubic arch allowing the head to extend. The fetal head is now born and will be facing the maternal back with its occiput anterior.
- During the next contraction, the shoulders, having reached the pelvic floor, will complete their rotation from a transverse position to an anterior-posterior position. Evidence of this manoeuvre happening inside can be visualised by seeing the head externally rotating as the fetus keeps its spine aligned.
Describe how the shoulders are delivered in labour.
- Downward traction by the healthcare professional will assist the delivery of the anterior shoulder below the suprapubic arch.
- This is followed by upward traction assisting the delivery of the posterior shoulder.
- The fetal body will be delivered by the contractions, the health professional’s role is only to assist safe negotiation of this last stage.
What is a complete breech?
This is when the baby is settled into an almost legs crossed position with their bottom down.
What is a frank breach?
This is when the baby’s bottom is down and their legs are straight up so their feet are close to their face.
What is an incomplete breech?
If one of the baby’s legs are bent (like sitting cross-legged) while the other one is trying to kick toward their head or another direction, they’re in an incomplete breech position.
What is a footling breech?
Both of baby’s feet are down in the birth canal so they would exit foot first.
What methods are used to monitor labour?
- Maternal observations: BP, temp, RR
- Abdominal palpation: find where baby is lying
- Vaginal examination
- Monitoring of liquor
- Palpation of contractions
- External signs: Rhomboid of Michaelis and anal cleftline
What is suboptimal progress defined as in the active first stage of labour?
- less than 0.5cm per hour primigravid women
- less than 1cm per hour for parous women
What can increase strength and dilation of contractions?
IV synthetic oxytocin
What is cephalopelvic disproportion?
The fetal head is in the correct position for labour but it is too large to negotiate the maternal pelvis to be delivered.
What casues relative CPD?
If there is malposition and the fetal head is in a suboptimal position for labour
List causes of obstruction during labour
Cephalopelvic disproportion
Placenta praevia
Fetal anomaly (hydrocephalus)
Fibroids
Describe malposition
Involves the fetal head being in a suboptimal position for labour and ‘relative’ CPD occurs. Occipital-posterior and occipital transverse. Assess position by feeling fontanelles
What are the possible causes of fetal distress?
Hypoxia, infection, cord prolapse, placental abruption and vasapraevia. No clear cause in many cases
Describe the process of fetal blood sampling.
Speculum used to take fetal scalp blood sample: need to be dilated (around 4cm) to do this
Used when abnormal CTG
Provides a direct measurement from baby: can measure pH and base excess. Can measure lactic acid.
How is fetal well being monitored in labour?
Intermittent auscultation of the fetal heart
Cardiotocography
Fetal blood sampling
Fetal ECG
What percentage of births are instrumental deliveries?
15%
What percentage of births are planned Caesarean sections?
20-30%
What percentage of births are emergency CS?
20-25%
What is shoulder dystocia?
A birth injury. One shoulder becomes stuck in pelvis. Normal traction on the fetal head does not lead to delivery of the shoulders. Can cause neonatal brachial plexus injuries, hypoxia and maternal trauma
What are the maternal complications of shoulder dystocia?
Damage to bladder and anal sphincter, rectum
Postpartum haemorrhage
What is a cord prolapse?
The umbilical cord slips through the cervix into the vagina after the waters break but before the baby descends into birth canal.
What is an occult (incomplete) cord prolapse?
The umbilical cord descends alongside the presenting part but not beyond it
What is an overt (complete) cord prolapse?
The umbilical cord descends past the presenting part and is lower than the presenting part in the pelvis
Where does cord prolapse occur most often?
Preterm babies
What can be a result of a cord prolapse?
Fetal distress from lack of oxygen. The prolapsed cord can become compressed by the baby’s body. Occurs in the presence of ruptured membranes.
What is the management of cord prolapse?
Avoid handling the cord to reduce vasospasm. Manually elevate the presenting part by lifting the presenting part off the cord by vaginal digital examination.
Encourage into left lateral position.
Delivery is usually via emergency Caesarean section.
What are the risk factors for cord prolapse?
Breech presentation Unstable lie Artificial lie Artificial rupture of membranes Excessive amniotic fluid around fetus Prematurity
