17 - Labour Flashcards
Why does methyldopa have to be stopped within 2 days of giving birth with gestational hypertension?
High risk of postpartum depression
What are Braxton-Hicks Contractions?
Irregular contractions that do not progress or become regular
Usually felt in second and third trimester
Stay hydrated and relax to avoid these
What are some signs of the onset of labour?
- Show (mucus plug from the cervix)
- Rupture of membranes
- Regular, painful contractions
- Dilating cervix on examination
What are the two parts of the first stage of labour?
Latent
- Painful contractions
- Changes to the cervix, with effacement and dilation up to 4cm
Established
- Regular painful contractions
- Dilatation of the cervix from 4cm onwards
What is the definition of the following obstetric terms:
- ROM
- SROM
- PROM
- P-PROM
- PROM (Prolonged)
Rupture of membranes (ROM): amniotic sac has ruptured
Spontaneous rupture of membranes (SROM): Amniotic sac has ruptured spontaneously.
Prelabour rupture of membranes (PROM): Amniotic sac has ruptured before the onset of labour.
Preterm prelabour rupture of membranes (P‑PROM): The amniotic sac has ruptured before the onset of labour and before 37 weeks gestation (preterm).
Prolonged rupture of membranes (also PROM): The amniotic sac ruptures more than 18 hours before delivery.
What are the different classifications of preterm labour?
Prematurity is delivery before 37 weeks gestation
Non-viable before 23 weeks gestation
How can preterm labour be prevented?
Vaginal Progesterone (Pessary or Gel)
- Prevents myometrium contracting and cervix remodelling
- Given to women with cervix <25mm on TVUS when 16-24 weeks gestation
Cervical Cerclage
- Put stitch in cervix and remove at term or when woman in labour
- Spinal or GA
- Cervical length <25mm on TVUA between 16 and 24 weeks gestation, who have had a previous premature birth or cervical trauma (e.g. colposcopy and cone biopsy)
What is a rescue cervical cerclage?
Between 16 and 28 weeks when there is cervical dilatation but no rupture of membranes to try and prevent progression
What is Preterm Prelabour Rupture of Membranes and how is it diagnosed?
Amniotic sac ruptures before onset of labour and before 37 weeks gestation
Dx
- Speculum Examination showing pooling of fluid in posterior fornix
- Test for Insulin-like growth factor-binding protein-1 (IGFBP-1) in vaginal fluid as this protein is in amniotic fluid
- Placental alpha-microglobin-1 (PAMG-1) same as above
How is premature prelabour rupture of membranes managed?
Prophylactic antibiotics: Prevent chorioaminonitis. Erythromycin 250mg four times daily for ten days, or until labour is established if within ten days
Induction of labour: offer from 34 weeks to initiate the onset of labour
What is preterm labour with membranes intact and how is it diagnosed?
Regular painful contractions and cervical dilatation, without rupture of the amniotic sac, before 37 weeks
- Speculum exam to assess cervical dilatation. If <30 weeks clinical assessment alone for management of labour. If >30 weeks do TVUS. Only offer management of preterm labour when cervical length <15mm
- Fetal fibronectin: alternative to TVUS. Found in the vagina during labour. A result of less than 50 ng/ml is considered negative, and indicates that preterm labour is unlikely
If preterm labour is diagnosed, what management is given to try to improve the outcomes?
- Fetal monitoring (CTG or intermittent auscultation)
- Tocolysis with nifedipine: CCB that suppresses labour
- Maternal corticosteroids: if <35 weeks
- IV magnesium sulphate: <34 weeks, neuroprotective for baby
- Delayed cord clamping or cord milking: can increase the circulating blood volume and haemoglobin in the baby at birth
What is tocolysis?
Medications given to stop uterine contractions. Given short term for 48 hours to allow administration of maternal corticosteroids and allow transfer to more specialised unit
Given between 24-34 weeks gestation with preterm labour
Nifedipine (CCB) or Atosiban (Oxytocin Receptor Antagonist)
Which antenatal steroids are given and what situations are they given in?
Suspected preterm labour before 36 weeks gestation
Given to help develop fetal lungs and prevent respiratory distress of the newborn
Two doses of intramuscular betamethasone, 24 hours apart.
When and how is magnesium sulfate given in pregnancy?
Helps to protect fetal brain and prevent/reduce severity of cerebral palsy
Given to mother via IV bolus and then infusion for 24 hours or until birth if preterm labour before 34 weeks
What does the mother need to be monitored for when she is given IV magnesium sulfate?
Magnesium Toxicity. Monitor observations and tendon reflexes every 4hours
Signs of Toxicity:
- Reduced respiratory rate
- Reduced blood pressure
- Absent reflexes
What are some risk factors for premature labour?
Conditions which may cause “overstretching of the uterus”
- Multiple pregnancy
- Polyhydramnios
Conditions where foetus is at risk
- Pre-eclampsia
- IUGR
Problems with the uterus or cervix
- Fibroids
- Congenital uterine malformation
- Short or weak cervix
Infection
Chorioamnionitis, maternal or neonatal sepsis, bacterial vaginosis, trichomoniasis, Group B Streptococcus, STIs, recurrent UTIs
Maternal co-morbidity
- Hypertension
- Diabetes
- Renal failure
When is induction of labour offered?
41-42 weeks gestation
Situations where it is beneficial to have early delivery
What is the Bishop score and how do you interpret the score?
Scoring system used to predict successful induction of labour
Score between 0 and 13. If over 8 then likely to have successful induction of labour
If less than 8 suggests some cervical ripening need to occur first
<6 then vaginal prostaglandins, if >6 then amniotomy and oxytocin infusion
What are the different options for induction of labour and when are they used?
Membrane Sweep
Used from 40 weeks gestation before trying induction. Finger in cervix to stimulate labour. Should produce onset in next 48 hours
Vaginal Prostaglandin E2 (Dinoprostone)
Insert gel, tablet or pessary into vagina. Prostaglandins stimulate cervix and uterus. Done in hospital
Cervical Ripening Balloon
Silicone balloon in cervix and gently inflated to dilate cervix. Usually used in women with previous C section, where prostaglandins have failed or multiparous >3 woman
Artificial Rupture of Membranes with Oxytocin Infusion
Only if there are reasons not to use prostaglandins. Also used to progress labour after prostaglandins
Oral Mifepristone plus Misoprostol
If intrauterine fetal death
What monitoring needs to be done once a woman has had an induction of labour?
- CTG
- Bishop Score to monitor progress
Induction of labour with PV prostaglandins usually makes women give birth within the next 24 hours. If this does not happen or progress is slow, what other options are there?
- Further vaginal prostaglandins
- Artificial ROM and Oxytocin Infusion
- Cervical Ripening Balloon
- Elective C-Section
What is the main complication of induction of labour with vaginal prostaglandins?
Uterine Hyperstimulation
Contraction of uterus prolonged and frequent causing fetal distress and compromise
What is the criteria for uterine hyperstimulation and what are the risks of this?
- Individual contractions lasting more than 2 minutes in duration
- More than 5 in 10 uterine contractions
Can cause:
- Fetal compromise with hypoxia
- Emergency C-Section
- Uterine Rupture
How is uterine hyperstimulation managed?
- Tocolysis with Terbutaline
- Remove vaginal prostaglandin
- Stop oxytocin infusion
What are some contraindications for induction of labour?
Same as vaginal delivery
Which method of induction is less likely to cause uterine hyperstimulation?
Mechanical over pharmacological
What observations do you need to do before induction of labour?
- Assess fetal head with abdominal exam
- Do US if concerns about fetal position
- Record Bishop score
- Confirm normal fetal heart rate pattern using CTG
- Confirm the absence of significant uterine contractions using CTG
What information do you need to give women about the risks of induction of labour?
- More painful than spontaneous labour
- Uterine hyperstimulation
- Uterine rupture
- May be unsuccessful induction
- Cord prolapse
What is a CTG and how do you put one on?
Cardiotocography
Used to measure fetal heart rate and contractions of uterus
One doppler US transduce above fetal heart, One US at fundus of uterus to look at tension in uterus
How do we read a CTG in general terms?
DR C BRAVADO
Define risk (high or low, if high lower threshold for intervention)
Contractions
Baseline rate
Variability
Accelerations
Decelerations
Overall impression (normal, suspicious, pathological or need intervention)
What are some indications for continuous CTG monitoring?
- Meconium
- Pre-eclampsia
- Fresh antepartum haemorraghe
- Sepsis
- Maternal Tachycardia >120
- Delay in labour
- Use of oxytocin
- Disproportionate maternal pain
How do we interpret the following on a CTG:
- Contractions
- Baseline Rate and Variability
- Accelerations
- *Contractions**
- How many in 10 minutes and how strong? (one big square per minute so how many in 10 squares)
- Any uterine hyperstimulation?
- Labour not progressing?
- *Baseline Rate and Variability**
- Normal baseline is 110-160
- Normal variability is 5-25
- *Accelerations**
- Sign that baby is healthy, especially when occurring during contraction
What are some causes of fetal tachycardia? (baseline >160bpm)
- Fetal hypoxia
- Chorioamnionitis
- Hyperthyroidism
- Fetal or maternal anaemia
- Fetal tachyarrhythmia
What are some causes of fetal bradycardia? (baseline <110bpm)
Normal to have baseline of 100-120 if post date gestation or OP
Severe prolonged bradycardia if <80 for 3 minutes or more and this indicates severe fetal hypoxia
What are some causes of reduced variability on a CTG?
- Fetal sleeping: should last no longer than 40 minutes
- Fetal acidosis due to hypoxia
- Fetal tachycardia
- Prematurity: variability is reduced at earlier gestation (<28 weeks)
- Congenital heart abnormalities
- Drugs: opiates, benzodiazepines, methyldopa and magnesium sulphate
What are the different types of decelerations on CTG?
Decelerations are due to fetal hypoxia
Early: Physiological. Start with contraction and lowest point at peak of contraction. Due to uterus compressing fetal head so stimulates vagal nerve slowing HR
Late: Fall in heart rate that starts after contraction has already begun and lowest point occurs after peak of contraction. Due to hypoxia, could be due to excessive uterine contractions, maternal hypotension or maternal hypoxia
Variable: Variable in duration and no relationship to contractions. Often due to intermittent compression of the umbilical cord. Accelerations before and after a variable deceleration are known as the shoulders of deceleration, indicating fetus is not yet hypoxic and is adapting to reduced blood flow. If no shoulders this is concerning
Prolonged: Drop of more than 15bpm from baseline lasting over 2 minutes. If over 3 minutes very concerning.
How do we interpret decelerations on CTG as reassuring, non-reassuring and abnormal?
Reassuring: No decels, early decels or variable decels of less than 90 minutes
Non-Reassuring: Regular variable decels, late decels
Abnormal: Prolonged decels
What are the four categories of CTG interpretation?
- Normal
- Suspicious: single non-reassuring feature
- Pathological: two non-reassuring features or single abnormal
- Need for urgent intervention: acute brady or prolonged decelerations of more than 3 minutes
How should you manage a CTG if it is suspicious or pathological?
Use image
- Escalate to senior midwife and obstetrician
- Further assessment for possible causes, such as uterine hyperstimulation, maternal hypotension and cord prolapse
- Conservative interventions: repositioning mother or IV fluids for hypotension
- Fetal scalp stimulation (an acceleration in response to stimulation is a reassuring sign)
- Fetal scalp blood sampling to test for fetal acidosis
- Delivery of the baby (instrumental or emergency c-section)
What does this CTG show and what could it be caused by?
Sinusoidal
Indicates severe fetal compromise. Usually due to severe fetal anaemia e.g vasa praevia with fetal haemorraghe
When is tranexamic acid used in labour?
Antifibrinolytic medication used to prevent and treat PPH
Binds to plasminogen and prevents it becoming plasmin and dissolving fibrin
How is progress monitored in the first stage of labour?
Partogram
- Cervical dilatation
- Descent of fetal head in relation to ischial spines
- Maternal pulse, BP, temp and urine output
- Fetal heart rate
- Frequency of contractions
- Status of membranes
- Drugs and fluids given
When there are issues with progress in the second stage of labour, what interventions can be done for this?
- Changing positions
- Encouragement
- Analgesia
- Oxytocine
- Episiotomy
- Instrumental delivery
- C-section
What are some pain relief options in labour?
- Paracetamol
- Codeine
- Gas and Air (Entonox)
- IM Pethidine or Diamorphine
- PCA IV Remifentanil
- Epidural
What is the process of an epidural and what medication is used?
Catheter into epidural space outside the dura mater
Local anaesthetics like levobupivicane or bupivicane mixed with fentanyl
What are some adverse effects of an epidural?
- Headache after insertion
- Hypotension
- Motor weakness in legs
- Nerve damage
- Prolonged second stage
- Increased likelihood of needed instrumental delivery
URGENT REVIEW IF SIGNIFICANT MOTOR WEAKNESS (CANNOT STRAIGHT LEG RAISE) AS CATHETER MAY BE IN SUBARACHNOID SPACE RATHER THAN EPIDURAL SPACE
What are the different types of instrumental delivery?
Forceps or Ventouse
Forceps has lower fetal complications rate but higher maternal complication rate
If after 3 contractions and pulls with instrument and no progress then abandon and C-Section
Also give dose of co-amoxiclav after to reduce maternal infection
What are some indications for an instrumental delivery?
- Failure to progress
- Fetal distress
- Maternal exhaustion
- Control of the head in various fetal positions
- Epidural not progressing
Often done in theatre so can covert to C-section if unsuccessful
What are some risks to mother and baby with an instrumental delivery?
Mother
- PPH
- Episiotomy
- Perineal tears
- Injury to anal sphincter
- Femoral or Obturator nerve damage
Baby
- Cephalohaemoatoma with Ventouse
- Facial Nerve Palsy, Bruises and Fat necrosis with Forceps
- Subgaleal haemorraghe (dangerous)
- Intracranial haemorraghe
- Skull fracture
- Spinal cord injury
What are some contraindications for instrumental delivery?
Absolute:
- Unengaged fetal head
- Incompletely dilated cervix
- True cephalo-pelvic disproportion
- Breech and face presentations
- Preterm gestation (<34 weeks) for ventouse.
- High likelihood of any fetal coagulation disorder for ventouse
What are the different classifications of perineal tear?
First Degree: Injury limited to frenulum of labia minor and superficial skin
Second degree: Include the perineal muscles but not the anal sphincter
Third degree: Include the anal sphincter but not rectal mucosa
Fourth degree: Include rectal mucosa
How are perineal tears managed?
- Suture if higher than first degree. If third or fourth may need to repair in theatre
- Broad spectrum abx
- Laxatives
- Physiotherapy to reduce risk of incontinence
- Follow up to monitor complications
In future can have elective C-Section if third or fourth degree tear
How can perineal tears be avoided?
- Perineal massage from 34 weeks onwards
- Perineal support during crowning. Also stop pushing when crowning and small quick breaths
- Mediolateral Episiotomy under LA if anticipate need additional room e.g before forceps. Avoids damage to anal sphincter
What are the steps of active management of the third stage of labour?
(if woman wants physiological but is haemorraghing or delay over 60 minutes then should switch to active)
- IM dose of oxytocin after delivery of baby
- Clamp and cut cord within 5 minutes of birth, give a delay of 1-3 minutes to allow blood to flow to baby
- Palpate abdomen to assess for a uterine contraction and then apply controlled cord traction during a contraction, stop if any resistance. At the same time other hand presses uterus upwards in opposite direction to prevent uterine prolapse
- Massage uterus until contracted and firm once placenta delivered. Inspect placenta to ensure it is complete
What are some indications for an elective c-section and when are these planned for?
Usually before 39 weeks gestation under spinal anaesthetic
- Previous c-section
- Symptomatic after previous significant perineal tear
- Placenta Praevia
- Vasa Praevia
- Breech
- Multiple pregnancy
- Uncontrolled HIV
- Cervical Cancer
What are the different incisions that are used during C-Section?
Usually done in a transverse plane in lower uterine segment
- Pfannensteil Incision
- Joel-Cohen Incision
- Vertical Incision: for premature or anterior placenta praevia
What are the layers that need to be divided during a C-Section?
- Skin
- Subcut tissue
- Fascia
- Rectus Abddominis
- Peritoneum
- Vesicouterine peritoneum and bladder
- Uterus
- Amniotic sac
What anaesthetic is used for a c-section and what are the risks with this?
Spinal Anaesthesia
Safer, Fewer complications and Faster recovery
What are the risks with a C-Section?
- General surgical risks
- Complications in post party period
- Damage to local structures
- Effects on abdominal organs
- Effect on future pregnancies
- Effects on baby
VBAC is successful in 75% of women. What are some contraindications to VBAC?
- Previous uterine rupture
- Classical or Vertical C Section scar
- Other usual contraindications e.g placenta praevia
What is the biggest risk with VBAC?
Uterine Rupture (0.5%)
Need continuous CTG monitoring as any change in heart rate could be sign of impending scar rupture
Risk of scar rupture is higher in labours that are augmented or induced with prostaglandins or oxytocin
What are the risks and benefits of VBAC compared to planned elective c-section?
- Lower maternal death rate
- Lower risks of adhesions
- Faster recovery
- No anal sphincter injury
What are some risk factors for uterine rupture?
Previous classical C-section is biggest risk factor
If a woman opts for a VBAC, how should this delivery be managed?
- Deliver in a hospital setting with facilities for emergency caesarean and advanced neonatal resuscitation
- Continuous CTG monitoring
- Beware of additional analgesic requirements during labour as may indicate impeding uterine rupture
- Avoid induction where possible, if required do mechanical over prostaglandins
- Be cautious with augmentation
What are some clinical features of meconium aspiration syndrome?
- Presence of meconium stained liquor
- Green staining of the infant’s skin, nail beds or umbilical cord
- Signs of respiratory distress in the newborn
- Limp infant or low APGAR score
- Crackles on auscultation of the foetal lungs
