Revision - Obs 6 Flashcards
What is secreted by the posterior pituitary?
1) ADH
2) Oxytocin
What class of drug is Atosiban?
Oxytocin receptor ANTagonist
Can be used as an alternative to nifedipine for tocolysis in premature labour.
Side effects of ergometrine?
1) HTN
2) Coronary artery spasm
3) D&V
Who should ergometrine be avoided in?
1) Pre-eclampsia
2) HTN
What is Syntometrine?
Syntometrine is a combination drug containing oxytocin (Syntocinon) and ergometrine.
What is one key prostaglandin to be aware of in labour?
Dinoprostone (E2)
What class of drugs inhibit prostaglandins?
NSAIDs e.g. ibuprofen
Impact of prostaglandins on BP?
Act as vasodilators and lower BP
(hence NSAIDs increase BP)
Indication of misoprostol in labour?
1) It is used as medical management in miscarriage, to help complete the miscarriage.
2) Used alongside mifepristone for abortions
3) Induction of labour after intrauterine fetal death
Indication of Mifepristone in pregnancy?
1) abortions (used alongside misoprostol for abortions)
2) induction of labour of labour after intrauterine fetal death
What class of drug is carboprost?
Synthetic prostaglandin analogue
Indication of carboprost?
Given as deep IM injection in postpartum haemorrhage where ergometrine and oxytocin have been inadequate
Contraindication of carboprost?
Asthma
Mechanism of tranexamic acid
1) Binds to plasminogen and activates it to plasmin (plasminogen activator)
2) Plasmin works by dissolve the fibrin within blood clots
3) Therefore, by decreasing the activity of the enzyme plasmin, TXA acid helps prevent the breakdown of blood clots –> reduces bleeding
When is delay in the first stage of labour is considered?
1) less than 2cm cervical dilatation in 4 hours
or
2) slowing of progress in multiparous women
There are two lines on the partogram that indicate when labour may not be progressing adequately.
What are these labelled?
‘Alert’ and ‘action’
The dilation of the cervix is plotted against the duration of labour (time). When it takes too long for the cervix to dilate, the readings will cross to the right of the alert and action lines.
What is crossing the ‘alert’ line on a partogram an indication for?
Amniotomy (artificially rupturing the membranes) and repeat examination in 2 hours.
What does crossing the ‘action’ line on a partogram indicate?
Care needs to be escalated to obstetric-led care and senior decision-makers for appropriate action.
When does delay in the 2nd stage of labour occur?
When the active 2nd stage (pushing) lasts over:
1) 2 hours in nulliparous women
2) 1 hour in multiparous women
When there are weak uterine contractions, what can be given to stimulate the uterus?
Oxytocin infusion
What does ‘attitude’ of the fetus refer to?
The posture of the fetus e.g. how rounded the back is, how the head and limbs are flexed.
What does the ‘lie’ of the fetus refer to?
The position of the fetus in relation to the mother’s body:
- transverse
- longitudinal
- oblique
What does the ‘presentation’ of the fetus refer to?
The part of the fetus closest to the cervix:
- cephalic
- shoulder
- breech
When does delay in the 3rd stage of labour occur?
1) >30 minutes with active management
2) >60 minutes with physiological management
What does active management of the 3rd stage of labour involve?
1) IV oxytocin
2) Controlled cord traction
During labour, patients may be offered the option of patient-controlled analgesia.
What drug is offered?
IV remifentanil (short acting opiate)
What 2 medications must be accessible if giving a patient patient-controlled remifentanil?
1) naloxone: for respiratory depression
2) atropine: for bradycardia
What are the 2 anaesthetic options for an epidural?
1) levobupivacaine
2) bupivacaine
These are usually mixed with fentanyl
What is the most significant risk factor for cord prolapse?
When the fetus is in an abnormal lie after 37 weeks gestation (i.e. unstable, transverse or oblique).
Why can retrofilling the bladder with 500-700ml of saline be helpful in cord prolapse?
As it gently elevates the presenting part (reduces compression on cord)
What is the biggest maternal risk factor for shoulder dystocia?
Diabetes: the risk is significantly higher, even with a similar-sized baby.
Often offered c-section.
Should the mother keep pushing or stop pushing in shoulder dystocia?
Stop pushing - worsens the impaction
Risk of fetal and maternal complicatiosn when using forceps vs ventouse in birth?
Forceps –> lower risk of fetal complications but a higher risk of maternal complications.
Ventouse –> higher risk of fetal complications but a lower risk of maternal complications.
What is recommended after instrumental delivery to reduce the risk of maternal infection?
A single dose of co-amoxiclav
To use the ventouse, where is the cup applied?
The cup is applied with its centre over the flexion point on the fetal skull (in the midline, 3cm anterior to the posterior fontanelle).
Where is the flexion point on the foetal head?
In the midline, 6 cm posterior to the anterior fontanelle or 3 cm anterior to the posterior fontanelle.
What is the main foetal complication of using a ventouse?
Cephalohaematoma
What is the main foetal complication of using forceps in delivery?
Facial nerve palsy, with facial paralysis on one side.
How are operative vaginal deliveries classified?
By the degree of foetal ascent:
1) Outlet
2) Low
3) Midline
The lower the classification, the less the risk of complications.
What defines an ‘outlet’ classification of operative vaginal delivery?
Any of the following:
1) Fetal scalp visible with labia parted
2) Fetal skull reached pelvic floor
3) Fetal head on perineum
What defines a ‘low’ classification of operative vaginal delivery?
Lowest presenting part (not caput) is +2, or further below the ischial spines.
Subdivided to:
> 45 degrees – rotation needed
<45 degrees – no rotation needed
What defines a ‘midline’ classification of operative vaginal delivery?
1/5 palpable abdominally
Lowest part is above +2, but is lower than the ischial spines
Subdivided to:
> 45 degrees – rotation needed
<45 degrees – no rotation needed
Features of femoral nerve damage?
- loss of patella reflex
- weakness of knee extension
- numbness of anterior thigh and medial lower leg
What additional measures re taken to reduce the risk of complications in perineal tears?
1) broad spectrum abx to reduce infection
2) laxatives to reduce risk of constipation and wound dehiscence
3) physiotherapy to reduce the risk and severity of incontinence
When would a woman with a perineal tear be ffered an elective caesarean section in subsequent pregnancies?
Women that are symptomatic after 3rd or 4th degree tears
What are some long term complications of perineal tears?
1) urinary incontinence
2) anal incontinence and altered bowel habit (3rd and 4th degree tears)
3) fistula between vagina and bowel (rare)
4) sexual dysfunction and dyspareunia (painful sex)
5) psychological & mental health consequences
What is one method for reducing the risk of perineal tears?
Perineal massage (massaging the skin and tissues between the vagina and anus).
This is done in a structured way from 34 weeks onwards to stretch and prepare the tissues for delivery.
What drug is given for active management of the 3rd stage of labour involve?
IM oxytocin
In what 2 scenarios is active management of 3rd stage of labour initiated?
1) haemorrhage
2) more than a 60-minute delay in delivery of the placenta (prolonged third stage)
What is PPH defined as?
1) loss of 500ml after vaginlal birth
2) loss of 1000ml after c-section
PPH can be classified into minor and major.
What defines a minor PPH?
<1000ml
What defines a major PPH?
> 1000ml
Major PPH can be further sub-classified as:
a) moderate
b) severe
What blood loss defines each?
a) 1000-2000ml
b) >2000ml
PPH can be categorised as primary and secondary.
Define 1ary PPH
Bleeding within 24h of birth
Define 2ary PPH
24h to 12w after birth
What does ‘tissue’ refer to in PPH?
Retention of placenta –> prevents uterus from contraction.
What does ‘thrombin’ refer to in PPH?
Coagulopathies and vascular abnormalities which increase the risk of 1ary PPH.
What vascular abnormalities can lead to PPH?
1) placental abruption
2) pre-eclampsia
3) HTN
Initial lab investigations in PPH?
1) FBC
2) Cross match 4-6 units of blood
3) Coagulation profile
4) U&Es
5) LFTs
What does the major haemorrhage protocol give rapid access to?
4 units of crossmatched or O neg blood
What must you ensure before starting to induce uterine contractions in PPH?
Bladder must be emptied –> catheterisation
Bladder distension prevents uterine contractions.
Why should women be catheterised in PPH?
As bladder distension prevents uterine contraction
What are some options for medical management in PPH?
1) Oxytocin
2) Ergometrine
3) Carboprost
4) Misoprostol
5) Syntocinon
6) Tranexamic acid
What are 3 contraindications for ergometrine?
1) HTN
2) pre-eclampsia
3) vascular disease
How is Misoprostol given in PPH?
Sublingual
Main side effect of misoprostol?
Diarrhoea
What are the 4 surgical options in PPH?
1) Intrauterine balloon tamponade
2) B-Lynch suture
3) Uterine artery ligation
4) Hysterectomy
What is 2ary PPH more likely to be due to?
1) retained products of conception
2) infection e.g. chorioamnionitis
2 key investigations in 2ary PPH?
1) US: for retained products of conception
2) Endocervical and high vaginal swabs for infection
What are 4 preventative measures that can reduce the risk and consequences of postpartum haemorrhage?
1) Treating anaemia during antenatal period
2) Giving birth with an empty bladder (a full bladder reduces uterine contraction)
3) Active management of 3rd stage of labour: with IM oxytocin in 3rd stage
4) IV tranexamic acid: can be used during caesarean section (in the third stage) in higher-risk patients
Active management of the 3rd stage of labour routinely reduces PPH risk by what?
60%
What category c-section is an elective c-section?
Cat 4
Why is Primary genital herpes (herpes simplex virus) in the 3rd trimester an indication for an elective c-section?
As there has been no time for the development and transmission of maternal antibodies to HSV to cross the placenta and protect the baby.
Why are elective c-sections usually performed after 39 weeks gestation?
To reduce respiratory distress in the neonate: known as Transient Tachypnoea of the Newborn (TTN).
What is the most commonly used skin incision in c-section?
Transverse lower uterine segment incision
What is the average blood loss at c-section?
500-1000ml
Why is a H2 receptor antagonist (e.g. ranitidine) +/- metoclopramide given as prophylaxis in c-section?
Ranitidine –> Decreases gastric acid secretion and may decrease gastric volume.
Metoclopramide –> An anti-emetic that increases gastric emptying).
This reduces the risk of aspiration of gastric contents into the lungs, leading to chemical pneumonitis.
Pregnant women lying flat for a Caesarean section are at risk of Mendelson’s syndrome.
What is this?
This is aspiration of the gastric contents into the lungs –> pneumonitis.
This is because of pressure applied by the gravid uterus on the gastric contents.
How is the risk of Mendelson’s syndrome in c-section reduced?
1) H2 receptor antagonist (e.g. ranitidine) +/- metoclopramide
2) PPIs as an alternative
How is the woman positioned in a c-section?
Left lateral tilt of 15 degrees –> to reduce the risk of supine hypotension due to aortocaval compression.
Sharp or blunt dissection into the abdomen is made through several layers in a c section.
What layers?
1) Skin & SC tissue
2) Camper’s fascia (superficial fatty layer of SC tissue)
3) Scarpa’s fascia, (deep membranous layer of SC tissue)
4) Rectus sheath, (anterior and posterior leaves laterally, that merge medially)
5) Rectus muscle
6) Abdominal peritoneum (parietal)
7) This reveals the gravid uterus (perimetrium, myometrium and endometrium) and then the amniotic sac.
What is Camper’s fascia?
Superficial fatty layer of SC tissue
What is Scarpa’s fascia?
Deep membranous layer of SC tissue
How many units of oxytocin is given in c-section?
5 units IV
Aids delivery of placenta by surgeon
Purpose of blunt dissection in a c section?
Used after the initial incision with a scalpel to separate the remaining layers of the abdominal wall and uterus.
Are prophylactic abx usually given in c-section?
Yes
What are 4 measures taken to reduce the risks during c-section?
1) H2 receptor antagonists (e.g. ranitidine) or PPIs (e.g. omeprazole) before the procedure
2) VTE prophylaxis w/ LMWH
3) Oxytocin during the procedure to reduce the risk of PPH
4) Prophylactic antibiotics during the procedure to reduce the risk of infection
How is fertility affected in c-section vs vaginal delivery?
There is a delay in conceiving post c-section compared to women who have had vaginal deliveries.
Potential effects on future pregnancies post c-section?
1) increased risk of repeat caesarean
2) increased risk of uterine rupture
3) increased risk of placenta praevia
4) increased risk of stillbirth
Planned VBAC is associated with what risk of uterine rupture?
1 in 200 (0.5%)
What is the success rate of VBAC?
75%
Contraindications for VBAC?
1) previous uterine rupture
2) classical c-section (vertical scar)
3) other usual contraindications to vaginal delivery (e.g. placenta praevia)
What should all women undergoing VBAC should have?
Continuous CTG monitoring
What increases the risk of uterine scar rupture in VBAC?
Risk is higher in labours that are augmented or induced with prostaglandins or oxytocin.
