Labour Flashcards
Describe the borders of the pelvic inlet and outlet. Why is it important to know the anatomy of the pelvic inlet + outlet for understanding labour?
Inlet: sacral promontory, arcuate line of the ilium, pubic symphysis
Outlet: pubic arch, ischial spines, coccyx
*Baby’s head must enter the inlet in the transverse plane (the widest part) and then turn to exit the outlet in the AP plane
What is the clinical relevance of the ischial spines?
- Site of pudendal nerve -> nerve block for LA during instrumental delivery/episiotomy
- ‘Station 0’, used when describing the level of the head during delivery. Can only use instruments when at station 0 or lower
Describe the anatomy of the fetal skull. Why is this relevant for labour?
- Bones have not yet fused. The meeting points are the anterior and posterior fontanelles
- Anterior: diamond shape
- Posterior: triangle shape
- Can feel the baby’s head PV during labour to assess the presenting part + attitude (head position)
What is the ideal presentation, position + attitude of the fetus?
Vertex presentation, occipito-anterior position
Well-flexed fetal head (or hyperextended)
Describe the changes that occur in the cervix prior to labour, and the mechanism for these changes.
Cervix softens, dilates, shortens, and thins (effacement).
Prostaglandins induce proteolysis, which breaks down collagen and elastin -> softening
There is also an increase in hyaluronan, which brings water- this is ‘ripening’
Describe the changes that occur in the uterus prior to/during labour, and the mechanism.
- Uterus has rhythmic, regular, strong contractions
- Stimulated by oxytocin and prostaglandins -> increase intracellular Ca2+
- Also have progressive shortening of the muscle fibres in the upper segment -> squeezing baby out
What is the Fergusson reflex?
Oxytocin released in response to pressure on the cervix
How would you diagnose the onset of labour? What is NOT the onset of labour?
- Presence of strong, regular, painful contractions
- Progressive cervical changes (dilatation + effacement)
- Labour does not necessarily begin with the loss of the mucus plug (the ‘show’) or rupture of membranes, though these can precede labour
Define the stages of labour.
1st stage: from the onset of contractions to full dilatation (10cm).
-Divided into the latent phase- up to 3-4cm. and the active phase- up to 10cm.
2nd stage: From full dilatation to delivery of the baby.
-Divided into the passive phase- no urge to push. and active 2nd stage- reflex to bear down.
3rd stage: delivery of the placenta and membranes
How long is a normal labour? How long is each stage?
Normal 1st labour is about 8 hours, 2nd is 5 hours.
- 1st stage: latent 3-8 hours, active 2-6 hours
- 2nd stage: passive 1-2 hours, active 1-2 hours
- 3rd stage: several mins
What would be classified as prolonged labour?
Total: over 12 hours in nulliparous, 8 hours in multiparous women
- 1st stage: if not dilating 1cm/2hours
- 2nd stage: if 1+ hours in multiparous, 2+ hours in nulliparous
- 3rd stage: if >30 mins
Describe the mechanism of labour.
- Engagement: head enters the pelvic inlet
- Descent
- Flexion of the head
- Internal rotation (OA/OP)
- Extension
- Restitution (head aligns with shoulders automatically)
- External rotation (shoulders move into AP plane)
- Delivery of shoulders
- Delivery of body
How are contractions quantified?
Usually the number in 10 mins
eg. 2 in 10, 5 in 10
When should a woman contact the labour ward?
When contractions are =<5 mins apart, or when there is rupture of membranes
What happens when a woman comes to labour ward in labour?
Take a history:
-Labour: contractions (onset, timing, frequency), ROM (colour, amount), PV bleeding, fetal movements
-Current pregnancy, birth plan
-Obstetric history (number, mode of delivery, size)
-PMH
General exam: vitals, urine dip
Abdo exam: lie, presentation, engagement, contractions
Vaginal exam: palpate cervix (length, dilatation, effacement) and presenting part (position, station, attitude)
–> either decide if for midwifery care or obstetric care
How should labour be monitored?
In established labour: -Contractions every 30 mins -HR every 1 hour -BP, temp, PV exam every 4 hours In the 2nd stage: -HR, BP, temp, exam every hour
How should you monitor the fetus during labour when there are no identified issues?
Auscultate the fetal heartbeat using Pinnard or Doppler USS. x15 mins during 1st stage, x5 mins 2nd stage.
What are the methods of fetal monitoring? When would they be indicated?
- Auscultate fetal heart beat. Initial monitoring
- Cardiotocography (CTG)/External fetal monitoring. If abnormal FHR, maternal pyrexia, PV bleeding, lots of meconium, oxytocin used
- Fetal scalp elctrodes (FES). If CTG not possible eg. high maternal BMI
- Fetal blood sampling (FBS). If there is an abnormal CTG
What is a partogram? What does it show?
Visual representation of labour.
Shows cervical dilatation, frequency + strength of contractions, head descent, station, fluid, obs
-Can indicate if there is slow progression/delay
How would you manage a woman in the 1st stage of labour?
If in the latent stage: send home and tell to come back later. Use simple analgesia
If in the active stage:
-1:1 midwifery care
-Adequate pain relief, hydration
-Encourage mobility
-Monitor maternal obs, fetus, and progress
*Do not rupture membranes if progressing well
How would you manage a woman in the 2nd stage of labour?
- Encourage to stand/all 4s/squat
- Stop pushing when head crowns
- Protect the perineum, flex the fetal head
What immediate care does the baby need after delivery?
- Clamp and cut the cord
- Apgar scores at 1 min + 5mins
- Dry + warm
- Vitamin K injection
- Skin-to-skin
How would you manage the 3rd stage of labour?
- Active management is best to reduce PPH risk- oxytocin and ‘controlled cord traction’
- 10 IU oxytocin IM
- Clamp and cut the cord
- Pull on the cord during contraction + push fundus away
- Examine placenta to ensure no placental tissue remaining
- Inspect vulva for tears
Broadly speaking, what the main ways in which labour can be abnormal?
Labour can go wrong when there is poor progress or fetal compromise.
Can be due to the 3 P’s:
-Powers: eg. insufficient contractions
-Passage: pelvic inlet/outlet not big enough, cervical dystocia
-Passenger: baby too big/malpositioned
What are the 3 main patterns of abnormal progress in labour? What are the risk factors for each?
- Prolonged latent phase. RF- primiparous
- Primary arrest (poor progress in active 1st stage)/secondary arrest (>7cm then arrests)
- Inefficient contractions (dysfunctional uterine activity), CPD, malposition/presentation - Arrest in the 2nd stage
- Also malposition/presentation, CPD, pain, exhaustion
How would you manage poor progress in the 1st stage of labour?
-Assess the contractions. This is the likely cause of slow progress in the 1st stage of labour.
If primiparous:
-Amniotomy/artificial rupture of membranes (ARM)
-Oxytocin infusion (slowly, increasing every 30 mins until contractions 4-5 in 10 mins)
-If no progress with 4-6 hours of oxytocin, proceed with C-section
If multiparous: be careful. Oxytocin can lead to uterine rupture.
What is cephalopelvic disproportion? What are the risk factors? How would you manage it?
- The head is too large to pass through the pelvis.
- RFs: small mum, large head, primigravidae
- Management: can use oxytocin if only mild/mod degree in primiparous. Do not give to multiparous!!
What is the most important thing to bear in mind when giving a woman an oxytocin infusion?
If she is primiparous/multiparous.
Oxytocin infusion in multiparous women may cause uterine rupture if the labour is obstructed. So you want to be very sure that there really are inefficient contractions before giving oxytocin.
What are some causes of poor progress in the 2nd stage of labour?
- Secondary dysfunctional uterine activity due to epidural, ketosis, dehydration
- Deep transverse arrest (head stuck in narrow midpelvis)
How would you manage poor progress in the 2nd stage of labour?
- Amniotomy
- Consider oxytocin if secondary uterine dysfunction
- Instrumental delivery +/- episiotomy
- Consider if C-section more appropriate
When would you diagnose delay in the 2nd stage of labour?
- 2 hours and birth not imminent in primiparous
- 1 hour and birth not imminent in multiparous
How would you manage suspected fetal compromise on CTG?
- If suspicious CTG (1 feature abnormal): change position, give IV fluids, decrease/stop oxytocin (Syntocinon)
- If abnormal CTG (2+ features abnormal): vaginal exam, FBS. Consider need for C section/instrumental delivery
What forms of pain management can you use during labour?
Non-pharmacological pain management: breathing exercises, warm bath/shower
Pharmacological:
1. Opiates eg. pethidine, diamorphine IM/SC/PCA. But SEs include drowsiness, N+V
2. Inhalational: NO/Entonox
3. Epidural
4. Spinal block
Name the indications, contraindications, and complications of an epidural.
- Indications: patient’s choice, prolonged labour, hypertension, multiple pregnancy, likely C section
- Contraindications: coagulopathy, sepsis, hypovolaemia
- Complications: increased 2nd stage duration, increased instrumental delivery, dural puncture –> headache (1%), bladder dysfunction if not catheterised, hypotension, accidental total spinal anaesthesia
T/F. Hypertension is a contraindication to the use of epidural analgesia
False. Hypertension is an indication.
What is the most significant risk of labour in a woman with a previous C section? How would this present?
1/200 risk of dehiscence in spontaneous labour.
Uterine rupture would present with severe pain, PV bleeding, haematuria, absence of contractions, tachycardia.
This can progress to maternal shock and death, and fetal hypoxia + death.
How many women with previous C sections go on to have a VBAC?
70-80%. Others will have another C section.
What are the contraindications for a VBAC?
- Induction of labour
- Suspected CPD
- Classical Caesarean scar
- Any absolute contraindications to vaginal birth eg. placenta praevia
How should VBAC be managed?
- In a labour ward with available obstetric team
- Close monitoring
- Continuous CTG
What percentage of deliveries occur via induction of labour?
20-25%
What are the indications for IOL?
- Prolonged pregnancy/post dates
- Prelabour rupture of membranes
- Pre-eclampsia/other hypertensive illness
- Considered in DM, multiple pregnancy, cholestasis
When should a woman with PROM have induction of labour?
- If >34 weeks: after 24 hours
- If <34 weeks: only if other indication eg. fetal distress, infection
What are contraindications to IOL?
Basically the same as contraindications to vaginal delivery:
- Placenta praevia
- Maternal HIV/active genital herpes
- Severe fetal compromise
- Ideally not in VBAC
- Ideally not in breech presentation
What is the Bishop score?
Scoring system used to assess cervix prior to the induction of labour, which helps predict outcomes.
-Looks at the dilatation, consistency, length, position, station
What is the 1st line method for IOL? What are some other methods?
-Membrane sweeping prior to formal IOL at 40+41 weeks in primiparous or 41 in multiparous
IOL: Vaginal prostaglandin E2 (gel, tablet, pessary)
-Proceed to amniotomy/ARM after 24 hours
-Oxytocin infusion
*Or can use Cook’s balloon
What are the complications of IOL?
Uterine hyperstimulation
- -> fetal bradycardia, compromise
- -> uterine rupture
- -> failure of induction
How should you manage IOL?
- Assess Bishop score prior to IOL, check fetus
- After IOL, need to monitor closely
- Patient should be admitted to labour ward
- CTG after IOL. Can stop if no problems
- Reassess Bishop score after 6 hours (gel/tablet) or 24 hours (pessary)
What are the different types of perineal trauma?
1st degree: skin only
2nd degree: involving perineal muscles
3rd degree: involving the anal sphincter
-a) <50% EAS b) >50% EAS c) Both EAS + IAS
4th degree: fascia, muscles, EAS + IAS, rectal mucosa
Define obstetric anal sphincter injury.
Significant perineal trauma in labour that involves the anal sphincter: 3rd or 4th degree tear
How common is perineal trauma? How common are 3rd degree tears?
Perineal trauma of some kind is very common!! About 80-90% of primiparous women.
3rd degree tears are less common, affecting only 0.5-3% of mothers
How do the different anal sphincter injuries affect bowel function?
- External anal sphincter injury: faecal urgency
- Internal anal sphincter injury: faecal incontinence
How should you manage an OASI?
- Proper examination of all women with VD to detect OASIS, may need pudendal block/epidural. Always examine rectum!
- Repair the OASI under regional/GA, starting with rectal mucosa
- Post-op: admit until 1st bowel movement
- Adequate analgesia
- BS antibiotics 5-7 days
- Laxatives
- Review at 6-12 weeks to assess for faecal + urinary symptoms
What investigations can be used to diagnose OASI?
- RCOG recommends clinical exam after delivery to detect OASIS
- Ix can be: anal manometry (tests pressures) or endoanal USS
T/F. Episiotomies are done prophylactically to reduce perineal trauma
FALSE. DO NOT do an episiotomy to prevent perineal tears.
Describe the indications for episiotomy. How should an episiotomy be done?
Indications: instrumental delivery eg. delay in the 2nd stage of labour, fetal compromise
Ensure adequate analgesia eg. epidural, pudendal block. Should cut at a 60degree angle from the midline, to avoid the Bartholins glands + decrease risk of anal sphincter injury
What are some complications of an episiotomy?
- Common: Pain, infection, bleeding.
- Also: dyspareunia, incontinence, urgency
Describe the indications for an operative vaginal delivery.
These can be divided into fetal or maternal.
- Fetal: fetal compromise (detected on CTG/FBS)
- Maternal: prolonged active 2nd stage (eg. no progress in 3/2 hours with epidural or 2/1 hour without), exhaustion, vomiting, distress
Describe the classification of forceps delivery. Which should not be done, or done with caution?
- Classification based on where the head is when forceps are applied
- Outlet: fetal head at perineum
- Low: station 2+
- Mid-cavity: station 0-1. Only do with senior help, in operating theatre in case of conversion to C section.
- High: station -1. Not appropriate level for forceps.
What are the contraindications to operative vaginal delivery?
- Cervix not fully dilated
- Head high (>1/5 palpable)/above ischial spines
- Ventouse should not be used in <34 weeks, caution in 35-36 weeks. Not used in face or breech presentation
What are the benefits and disadvantages of forceps over ventouse?
- Ventouse are superior to forceps in having lower risk of maternal trauma, less post-op pain, and lower risk of facial palsy
- Forceps are superior to ventouse in lower risk of failure, cephalhaematoma, and retinal haemorrhage
- Whether the presentation is OA or OP
Describe the preparation for OVD
- Consent the patient prior to delivery
- Abdo and pelvis exam to determine if suitable for OVD
- Ensure adequate analgesia: epidural (esp. forceps), pudendal block (rigid ventouse)
- Position the patient: lithotomy, empty bladder
- Choose the instrument
- Consider episiotomy
In which cases would you use soft/rigid ventouse, and rotational/non-rotational forceps?
Ventouse:
-Soft: uncomplicated OA
-Rigid: complicated OA, OP
Forceps:
-Rotational (Kielland): if >45 degree rotation from OA
-Non-rotational (Neville Barnes, Simpson): OA
Name some complications of OVD
- Pain, bleeding, infection
- Episiotomy + those risks (dyspareunia, incontinence)
- Faecal incontinence
- Fetal head trauma, intracranial haemorrhage
Describe the classification of C section emergencies
Category 1: immediate threat to life
Category 2: No imminent threat to life
Category 3: Requires early delivery
Category 4: At a suitable time
Describe the indications for Caesarean section delivery
- Previous C section
- Malpresentation
- Multiple pregnancies
- HIV/active genital herpes
- Failure to progress (often in the 1st stage)
- Fetal compromise
- Placental abruption, praevia
- Maternal illness
Describe the C section procedure
- Informed consent
- Analgesia: spinal, epidural, GA
- Catheterise, empty bladder
- Antibiotics prior to incision
- Abdominal incision: best is transverse Joel-Cohen > Pfannenstiel. Divide rectus muscles
- Uterine incision: transverse incision in the lower segment
- Deliver baby
- Syntocinon IV, remove placenta
Describe the common and uncommon complications of C section
Common: bleeding, infection, pain, transient tachypnoea of the newborn
Uncommon: bladder or bowel injury, VTE, hysterectomy (uncontrolled haemorrhage, uterine atony, rupture), future placenta praevia, future uterine rupture
Describe any post-operative management of C section.
- Close monitoring
- Wound care
- Analgesia
- Encourage early mobilisation to prevent VTE
- Other VTE prophylaxis as indicated: stockings, LMWH
- Remove catheter after mobilising
What are the benefits and disadvantages of ERCS?
- ERCS benefits: avoids labour with risk of trauma to pelvic floor, no need for emergency C section, avoids risk of uterine rupture!
- ERCS downsides: increased blood loss, infection risk, VTE risk, increased risk of future placenta praevia
Define preterm labour. What type of labour/delivery does this include?
Onset of labour before 37 weeks (contractions + cervical changes +/- ROM)
- Spontaneous preterm labour
- IOL/delivery before term
- PPROM
Name some risk factors for spontaneous preterm labour
- Pre-existing: young/old age, substance abuse, smoking, cervical incompetence, uterine abnormality
- Current maternal: primiparity, infection, multiples, haemorrhage, stress
How can infection lead to preterm labour?
Progesterone (maintains pregnancy) is suppressed by NFkB, which is increased during infection + inflammation. Also prostaglandin production triggers cervical changes
A woman comes in to MAS at 28+4 with regular, painful contractions. How would you approach this case?
- History: onset + timing of contractions, ROM, fetal movements, bleeding, discharge + fever. Obs Hx, etc.
- Obs and urine dip
- Exam: abdo exam, speculum. Swabs for infection, FFN
- USS +/- CTG
A woman comes in to MAS at 28+4 with regular, painful contractions. Her FFN is negative. Should she be admitted?
Can consider, but it is very unlikely that she is in preterm labour. She can go home with safety net
A woman comes in to MAS at 28+4 with regular, painful contractions. Her FFN is positive. Should she be admitted?
Yes. She is likely in preterm labour and should be admitted for corticosteroids and tocolysis
What is a tocolytic? Name some. Which is 1st line?
A tocolytic is a medication that slows down uterine contractions to prevent/delay labour (usually PTL).
- CCBs eg. Nifedipine. 1st line.
- Oxytocin antagonists eg. Atosiban.
- NSAIDs eg. Indomethacin. SEs for fetus (premature closure of DA, NEC, renal problems)
- B2 agonists eg. Salbutamol, Ritodrine. Bad SEs (pulmonary oedema)
- Mg sulphate. Poor evidence! Still given as neuroprotection
A G1P0 woman comes in to MAS at 28+4. She reports feeling a gush of fluids earlier this morning. She is afebrile, cervix is 1cm dilated. How would you manage this case?
- Admit for monitoring and treatment. Aim to delay labour until term!!
- Monitoring: bloods, frequent maternal obs, CTG
- Treatment: corticosteroids, IV erythromycin 250 mg QDS
A G1P0 woman comes in to MAS at 37+1. She reports feeling a gush of fluids earlier this morning. She is not having any contractions, is afebrile, and cervix is 2cm dilated. How would you manage this case?
- Admit for monitoring and expectant management
- Monitoring: bloods, frequent maternal obs, CTG
- Treatment: offer IV erythromycin 250mg QDS
- If not in labour in 24 hours –> IOL
How can we identify women at risk of preterm labour?
- Previous history of preterm labour
- History of cervical trauma
- TVUSS to assess cervical length
How can we prevent preterm labour?
Vaginal Progesterone starting at 16-24 weeks, continue until 34 weeks
Prophylactic or ‘rescue’ cervical cerclage
What are the indications for vaginal progesterone and cervical cerclage?
Vaginal progesterone: Hx of spontaneous PTD (<34 weeks) or mid-trimester loss (>16 weeks) +/or cervix <25mm
Prophylactic cerclage:
-Hx of spontaneous PTD (<34 weeks) or mid-trimester loss (>16 weeks) AND cervix <25mm.
-Cervix <25mm AND Hx of cervical trauma
‘Rescue’ cerclage:
-Cervical dilatation w/o contractions/labour between 16-27+6 weeks
A G1P0 woman comes in to antenatal clinic at 22+1. She previously had a spontaneous PTD at 33 weeks. On TVUSS, her cervix measures 20mm in length. On examination her os is closed. What discussion would you want to have with this woman?
- Explain the risks of PTL in this pregnancy
- Explain the options of vaginal progesterone or cervical cerclage for prevention of PTL
Describe the types of cervical cerclage approach.
- McDonald transvaginal (at cervicovaginal junction, no bladder mobilisation
- Shirodkar/high transvaginal (after bladder mobilisation)
- Transabdominal approach
Define the postpartum period
-6 weeks following delivery
What are the normal physiological changes in the postpartum period?
- Uterine involution: process of returning to normal nongravid uterus. Occurs via autolysis, accelerated by oxytocin
- Cervical closure: internal os should be closed by 2 weeks. External may remain open
- Lochia production: blood stained discharge, normal for several weeks. Phases: rubra (first few days- blood), serosa, alba (thin yellow-white discharge for 1 month)
- HPG axis returns to normal but can be suppressed by breastfeeding
Describe the various factors of recovery after a normal SVD
- Perineum: tearing very common. Painful for days-weeks. Can use simple analgesia, topical numbing creams, salt baths. Keep clean with water, change pad frequently. Safety net for infection: swelling, discharge, fever, redness.
- Bladder function: normal to have some voiding difficulty and increased urine production. Should pass 300ml by 6 hours post-delivery. If not voiding, consider catherisation, depending on PVV leave in longer.
- Bowel function: constipation is very common. Advise fluids +fibre intake. Prescribe laxatives as needed esp. tears (lactulose)
What are important things in the recovery from C section?
- Pain management
- VTE prophylaxis: mobilisation, hydration, LMWH
- Bladder + bowel function
- Wound care: clean with water
- Anaemia: measure Hb postop for iron supplementation
What is important to safety net when discharging a woman postpartum?
- PPH: discharge is normal, lots of blood is not.
- Pre-eclampsia: headache, vision changes
- Infection: fever, pain in the wound/perineum
- VTE: swelling in the calf, shortness of breath, chest pain
Describe normal postpartum care
- Reviewed before discharge, given written info and safety-netted, breastfeeding review
- Seen by midwife 1-2 times in first 10 days: recovery, lochia, bladder + bowels, mental health, BP measured. Baby wellbeing, breastfeeding.
- GP visit at 6 weeks: bladder, bowels, sexual function including contraception. Mental health. Urine dip.
What are some key conditions/problems that occur in the postnatal period?
- Hypertension (pre-eclampsia + eclamptic fits)
- VTE
- Infection
- PPH
Describe the postpartum management of pre-eclampsia
- Keep on postnatal ward for review of BP and ensure control and no symptoms before discharge
- If on antihypertensives: measure BP every 2 days until normotensive and off meds
- GP to review at 2 weeks
Define secondary PPH. What are some causes? How do you differentiate between causes?
- Secondary PPH is bleeding that occurs between 24 hours and 6 weeks after delivery
- Can be due to retained tissue, tears, infection, etc.
- Examination important: with retained placenta the os may be open still with visible tissue, uterus not involuted. With infection, the os will be closed, uterus tender, fever
What is the management of secondary PPH?
- Usually due to retained placenta and/or infection
- Empirical antibiotics
- Removal/evacuation of retained products may be needed
What is puerperal sepsis? What are the common causative organisms?
Puerperal sepsis is a complication of genital tract infection in the postnatal period.
It is commonly caused by Group A Strep (pyogenes), E coli, Staphylococcus, etc.
