Flashcards in Obstetrics: Labour Deck (67):
What are the three stages of labour?
First stage (Latent) up to 3/4cm dilatation
First stage (Active stage): 4cm - 10cm dilatation
Second stage: Full dilatation - delivery of the baby
Third stage: Delivery of the baby - expulsion of the placenta and membranes
Describe what happens in the first stage of labour
Latent: Mild irregular uterine contraction, cervix shortens and softens. (can last a few days)
Active: 4cm - full dilatation. There is a slow descent of the presenting part and contractions progressively become more rhythmic and stronger.
When is the second stage of labour considered prolonged?
Nulliparous women: 3 hours with regional anaesthesia, 2 hours without
Multiparous women: 2 hours with regional anaesthesia, 1 hour without.
How long on average does the third stage of labour last?
After how long would you wait in the third stage of labour before you started to make preparations for surgical removal?
Is the risk of post partum haemmorrhage higher with expectant or active management of the third stage?
Expectant. Active managment is preferred for lowering the risk of PPH.
What is involved in the active management of the third stage of labour?
Oxytocin 10 units
Cord clamping and cutting
Controlled cord traction
Injection of oxytocin directly into the cord.
What is the difference between braxton hicks contractions and labour contractions?
Braxton hicks contractions are irregular and do not increase in frequency or intensity and resolve with ambulation or change in activity.
Labour contractions are evenly spaced and the time between them gets shorter and shorter and the get more intense and painful over time. The cervix also thins in true labour.
What is the normal fetal position before labour?
Longitudinal lie. Cephalic presentation with the presenting part being the vertex. Head is flexed initially in occipito anterior position and then the head engages in occipito transverse.
What five parameters are evaluated when looking at the cervix?
Level of the presenting part
What is the bishops score?
Method of grading the position, consistency, dilatation and station of the fetus in the pelvis in order to determine if it is safe to induce labour.
What does a bishops score of less than 5 tell us?
Labour is unlikely to start without induction.
What does a bishops score of between 5 and 9 tell us?
It is likely that induction will be needed
What does a bishops score of more than 9 tell us?
Labour in likely to commence spontaneously
What are the three classical signs that indicate separation of the placenta?
1. Uterus contracts, hardens and rises
2. Umbilical cord lengthens permanently
3. Gush of blood variable in amount.
What physiological mechanisms are in place to maintain haemostasis in labour?
1. Tonic contraction - the lattice pattern of the uterine muscles strangulate the blood vessles
2. Thromobosis of the torn vessel ends as pregnancy is a hyper coagulable state.
3. Myo tamponade - opposition of the anterior and posterior walls.
How long does it take for the tissues to return to the non pregnant state?
~ 6 weeks
What medications are in an epidural anaesthesia?
Levobupvicaine +/- opiate
What the main side effects of epidural anaesthesia?
2. Atonic bladder
3. Dural puncture
5. Back pain
What level of dilatation suggests that there might be a failure to progress in stage 1 of labour?
Nulliparous: Less than 2cm in 4 hours.
Parous: Less that 2cm in 4 hours or slowing in progress
What are the "three p's" that can cause a failure to progress in labour?
1. Powers (Inadequate contractions)
2. Passages (short stature/trauma/shape of pelvis)
3. Passenger (Large baby, malposition)
What does a partogram emasure?
When is a partogram started?
As soon as the woman enters the labour ward
How is the fetus monitored in a normal first stage of labour?
Intermiitent auscultation of the fetal heart using a pinard stethescope or a doppler ultrasound immediately after a contraction for at least 1 minute every 15 minutes.
What are the indications for a continuous CTG in labour?
1. Maternal pulse over 120 bpm on 2 occasions 30 minutes apart
2. Temperature of 38 or above on a single reading or above 37.5 on 2 consecutive occasions 1 hour apart.
3. Suspected chorioamniotitis or sepsis
4. Pain that is different from the pain usually associated with contractions
5. Pre term/post dates
6. Hypertenion/Pre eclampsia
What is chorioamnionitis?
Inflammation of the fetal membranes (amnion + chrion) due to bacterial infection. It is most associated with prolonged labour and the risk in increased with each vaginal examination that is performed in the final month of pregnancy.
A woman who has had a prolonged labour has a temperature of 39 degrees, a heart rate of 120bpm, a very tender uterus and has passed fouls melling amniotic fluid. What are you worried about?
How is the fetus monitored in the second stage of a normal labour?
Every 5 minutes during and after a contraction for 1 minute and check maternal pulse at least every 15 minutes.
What 4 important things are assessed and documented on a CTG?
1. Baseline fetal heart rate
2. Baseline variability
3. Presence or absence of decelerations
4. Presence of accelerations
What is a normal/ reassuring baseline fetal heart rate?
100 - 160bpm
What is a normal/reassuring baseline variability on a CTG?
5 - 25 beats in a minute
Is it normal to have decelerations on a CTG?
It is normal to have no decelerations or early decelerations
What would be worrying level of baseline variability of the fetal heart in labour?
Less than 5bpm for 30 - 90 minutes
What would be an abnormal/worrying baseline fetal heart rate in labour?
Above 180 or below 100.
What elements are you reporting when you read an ECG?l
1. Determine risk
8. Overall impression
What are you looking for when assessing decelerations in labour?
1. Timing in relation to the peaks of the contractions
2. Duration of the individual decelerations
3. Whether or not the fetal heart rate returns to baseline
4. How long they have been present for
5. Whether they occur with over 50% of contractions
6. Presence or absence of a biphasic (W) shape
7. Presence or absence of shouldering
8. Presence or absence of reduced variability within the deceleration.
What are non reassuring signs with regards to decelerations on the CTG?
1. Variable decelerations for 90 minutes or more (even with no concerning characteristics)
2. Variable decelerations with any concerning characteristics in up to 50% of contractions for 30 minutes or more
What are abnormal signs with regards to decelerations on CTG?
1. Variable decelerations in over 50% of contractions for 30 minutes
2. Late decelerations for 30 minutes (or less if there are risk factors)
3. Acute bradycardia or single prolonged deceleration lasting 3 minutes of more
What do you do if you see acute bradycardia or a single prolonged deceleration for 3 minutes or more on a CTG?
- Urgent obstetric help
- If there has been an acute event (such as a cord prolapse, placental abruption or uterine rupture) then they will likely have to have an emergency C section
What is a normal scalp pH on fetal blood sampling?
Over 7.25. No action would be taken
What does it mean if there is a fetal scalp pH of between 7.20 and 7.25?
This is a borderline result and should be repeated in 30 minutes
What does it mean if there is a fetal scalp pH of over 7.25?
This is abnormal and the baby should be delivered.
What are the indications for operative vaginal delivery (forceps or vacuum)
- Delay (failure to progress in stage 2)
- Fetal distress
- Maternal cardiac disease
- Severe pre eclampsia or eclampsia
- Intra partum haemmorrhage
- Umbilical cord prolapse in stage 2
Is the risk of a fourth degree tear more common with a ventouse or forceps delivery?
More common with forceps (8 - 12%)
Ventouse risk is around 4%
What are the risks of a ventouse delivery to the baby compared to forceps?
1. Increased failure rate
3. Retinal haemorrhage
What are the main indications for a caeserean section?
1. Previous caesarean section
2. Fetal distress
3. Failure to progress in labour
4. Breech presentation
5. Maternal request
What is the mortality rate of a caesarean section compared to a vaginal delivery?
4 x greater mortality with a caeserean
Also significant morbitiy from sepsis, haemorrhage, VTE, trauma
Describes the methods used for induction of labour
1. Membrane sweeping - this is done at 40 and 41 week antenatal visits for nulliparous women and 41 weeks for parous woman.
2. Vaginal prostoglandins are the preferred method of induction and are given as a gel, a tablet of pessary. These are given one dose and then a second dose 6 hours later if labour is not established.
3. Amniotomy +/- oxytocin
What is a potential complication of induction of labour?
What is uterine hyperstimulation?
It occurs as a potential complication of induction of labour and is defined as a series of single contractions lasting 2 minutes or more OR five or more contractions in 10 minutes.
What drugs are used if there is uterine hyperstimulation during induction of labour?
Terbutaline (Beta 2 agonist)
What should you do if uterine rupture is suspected?
Delivery by emergency caesarean section
How do you induce labour in a women who has had an intrauterine fetal death?
Oral mifepristone followed by vaginal prostoglandin or vaginal misoprostol
What are the options for pain relief in labour?
Entonox (50:50 micture of oxygen and nitrous oxide)
Opiods (pethidine, diamorphine)
How do you manage delay of the first stage of labour?
What is lochia?
Bleeding that occurs for the first 2 weeks after giving birth. It is usually initially fresh bleeding which then becomes brown in colour before stopping.
What volume is blood loss is defined as a post partum haemmorhage?
What is a primary PPH?
- Occurs within 24 hours of birth.
- Most common cause is uterine atony.
What is a secondary PPH?
Occurs between 24 hours and 12 weeks.
This is due to retained placental tissue or endometritis
What are the risk factors for PPH?
Increased maternal age
Emergency caesarean section
Placenta previa, placenta accreta
If a woman has group B strep in one pregnancy what is her risk of having it in her next? What should be done about this?
They should be offered IV antibiotic prophylaxis in labour
Who should be given benzyl penicllin in labour for group B strep?
1. Women who have had group B strep detected in a previous pregnancy
2. Women with a previous baby with early or late onset group B strep
3. Any woman in pre term labour
What antibiotic is given for group B strep prophylaxis is labour?
What is the management for a woman who presents with pre term prelabour rupture of membranes?
2. Regular observations to look for chorioamnionitis
3. Oral erythromycin for 10 days
4. Antenatal corticosteroids (to reduce the risk of respiratory distress syndrome)
5. Delivery at 34 weeks.
What is syntocin and when is it used?
Synthetic version of oxytocin that is used in he active management of the third stage of labour. It stimulates the contraction of the uterus reducing the risk of postpartum haemorrhage. It is also used to induce labour.
What is ergometrine and when is it used?
An alpha adrenergic, dopaminergic drug that also acts of seratonin receptors. It exerts an effect on the uterus and other smooth muscles and causes powerful contractions of the uterus. It is used in the third stage of labour (given as an IM injection after delivery of the baby)