2. Obstetrics Flashcards
Q1 — Pre-eclampsia
A 25-year-old woman who is 37 weeks pregnant and known to have preeclampsia
is admitted to the labour ward with a blood pressure of
160/110mmHg on several readings.
a) What is the definition of pre-eclampsia?
Pre-eclampsia is a multisystem disorder with:
● Hypertension (BP >140/90mmHg) presenting after 20 weeks’
gestation.
● Significant proteinuria, i.e,
spot urinary protein: creatinine ratio
>30mg/mmol or a
24-hour urine collection with >300mg protein.
b) Define gestational hypertension.
Hypertension presenting after 20 weeks’ gestation without significant
proteinuria.
c) How can you define severe pre-eclampsia?
Proteinuria with severe hypertension (BP >160/110mmHg).
OR
Mild to moderate hypertension (140/90 to 159/109mmHg) with any of the
following features:
● Severe headache.
● Visual disturbance such as flashing lights or blurring.
● Vomiting.
● Subcostal pain.
● Papilloedema.
● Clonus (³3 beats).
● Liver tenderness.
● Thrombocytopenia (<100 × 109/L).
● Abnormal liver enzymes.
● HELLP syndrome
d) Explain the pathogenesis of pre-eclampsia.
**
● Impaired trophoblastic cell invasion.
● Failure of spiral artery dilatation.
● Placental hypoperfusion and hypoxia.
● Releases cytokines and inflammatory factors into the maternal
circulation triggering endothelial dysfunction.
● Increase in vascular reactivity, permeability, and coagulation cascade
activation.
● Organ damage.
e) Which related symptoms should pregnant women be told to
report immediately?
● Severe headache.
● Problems with vision, such as blurring or flashing before the eyes
● Severe pain just below the ribs or abdominal pain.
● Vomiting.
● Sudden swelling of the face, hands or feet.
● Reduced foetal movement.
f) How should this patient be monitored following admission to
the labour ward?
● Obstetric consultant-led care with input from anaesthetic and
neonatology teams.
● Monitor for signs and symptoms of severe pre-eclampsia.
● Monitor with the following — ECG, NIBP/IABP, pulse oximetry, RR,
fluid input/output, hourly reflexes.
● Six-hourly blood tests to monitor the platelet count, renal function
and liver enzymes.
● Foetal monitoring — US scan and CTG.
g) How would you control BP in this patient?
Maintain systolic pressure <150mmHg and diastolic pressure 80-
100mmHg.
● Reduce BP at the rate of 1-2mmHg per minute.
● First-line — oral labetalol.
● Oral methyldopa and nifedipine if labetalol is contraindicated
(bronchial asthma).
● Refractory hypertension — administer IV labetalol or IV hydralazine.
● Intra-arterial BP monitoring and HDU care may be considered.
h) What changes would you make to your airway management for
a pregnant woman, if this woman needed a general anaesthetic
for a caesarean section?
Anticipate a difficult airway.
● Manage the hypertensive response to laryngoscopy with alfentanil,
remifentanil, esmolol, atenolol.
● Manage hypertension at emergence with the same drugs.
● Smaller size ETT due to upper airway oedema.
● Gentle airway instrumentation to avoid trauma
i) What are the other considerations for GA?
● Non-depolarising muscle relaxants are potentiated by magnesium
sulphate; hence, smaller doses should be used with neuromuscular
monitoring.
● Appropriate neonatal resuscitation facilities.
● A higher risk of PPH but avoid ergometrine.
● Good postoperative analgesia/regional techniques like TAP blocks.
● Avoid NSAIDs.
● The likelihood of postoperative airway oedema
and pulmonary
oedema.
● Postoperative HDU/ITU care.
j) What are the complications of pre-eclampsia?
Maternal complications:
● Eclampsia.
● Intracerebral haemorrhage.
● Pulmonary oedema.
● Acute renal failure.
● Liver dysfunction.
● Coagulation abnormalities
Foetal complications:
● Abruptio placentae.
● Intrauterine growth restriction.
● Premature delivery.
● Intrauterine foetal death.
Q2 — Postdural puncture headache
The obstetric team tell you about a patient who is 2 days postpartum with
a suspicion of a postdural puncture headache (PDPH).
a) What is the differential diagnosis for this patient with a
suspected postpartum headache?
● Non-specific — dehydration, caffeine withdrawal, sleep deprivation.
● Tension headache.
● Lactation headache.
● Migraine.
● Sinusitis.
● Pre-eclampsia/eclampsia.
● Cortical vein thrombosis.
● Subarachnoid haemorrhage.
● Posterior reversible leukoencephalopathy syndrome.
● Space-occupying lesion — brain tumour, subdural haematoma.
● Cerebral infarction/ischaemia.
● Meningitis, encephalitis.
b) What features, in this patient, would lead you to consider a
serious underlying cause?
● Focal neurological deficit.
● Seizures.
● Altered conscious level.
● Absence of postural component.
● Presence of infectious markers.
● Hypertension and proteinuria — pre-eclampsia/eclampsia.
c) What is the mechanism/pathogenesis of headache in PDPH?
CSF leakage and a decrease in intracranial pressure causes:
● Traction on unsupported intracranial pain-sensitive structures such as
the tentorium and blood vessels.
● Compensatory vasodilatation of intracranial blood vessels.**
d) List the clinical features of PDPH.
● 90% of headaches develop within 3 days of the procedure.
● Headache is often frontal-occipital.
● Aggravated in the upright position, and when coughing or straining.
● Relieved on lying down.
● Associated symptoms include neck stiffness, nausea and vomiting,
visual disturbance, photophobia, auditory symptoms, cranial nerve
palsies.
e) List the management strategies for this patient who is suffering
with a PDPH.
f) You diagnose a PDPH and arrange treatment by an epidural
blood patch (EBP). How is an epidural blood patch performed?
● Obtain consent.
● IV access.
● Complete asepsis by both anaesthetists.
● Position the patient — usually laterally for patient comfort.
● Performed at or one space below the original site of dural puncture.
● The epidural space is identified.
● The assistant should aseptically withdraw 20ml of blood from a
peripheral vein.
● 10-20ml should be injected into the epidural space.
● Should radicular pain occur, slow or stop injecting.
g) What advice would you give to the patient after an EBP?
● Post-procedure, the patient should lie flat for 1-2 hours.
● Refrain from vigorous activity or lifting for a few days.
● Consider prescribing stool softeners to avoid constipation.
● Before leaving hospital, patients should be counselled to report fever,
severe back pain, or radicular pain immediately
h) Describe the mechanism of action of EBP.
● Tamponade effect of blood in the epidural space.
● Increased intracranial pressure and relief from headache.
● Formation of a clot seals the puncture site preventing further CSF
leak
i) What are the described risks of an EBP?
Risk of an epidural:
● Dural puncture.
● Permanent and temporary nerve damage.
● Meningitis.
● Risk of haematoma.
Risk of an EBP:
● Early complications:
- backache during injection;
- fever;
- bradycardia;
- seizures.
● Late complications include:
- meningitis;
- subdural haematoma;
- arachnoiditis;
- radicular pain;
- recurrence of headache.
a) Which methods of testing may be used to confirm the
adequacy of a spinal (intrathecal) block for an elective
caesarean section?
Sensory block:
● Temperature — ethyl chloride spray/cold sensation.
● Pin prick.
● Pressure.
● Touch.
● Proprioception, vibration.
A block to cold sensation at T2-4 and pin prick at T4-T5 confirms the
adequacy of the block for a caesarean section.
Motor block using the Bromage scale:
● 0 = no motor block.
● 1 = inability to straight leg raise but able to move knee and feet.
● 2 = inability to straight leg raise or move knee, able to move feet.
● 3 = complete motor block.
A score of 3 indicates a higher lumbar block.
Autonomic block:
● Hypotension.
● Bradycardia.
● Temperature changes
b) Describe the actions you could take if your spinal block proves
inadequate on testing prior to starting surgery for an elective
(category 4) caesarean section.
● Tilting the patient head down.
● If there is no evidence of block after 20 minutes, repeat the same
dose of spinal or do a combined spinal epidural.
● If the block is inadequate, consider an epidural catheter and gradual
top-ups. Repeating the spinal in this case may lead to a high/total
spinal.
● Consider GA.
● Discussion with the mother, surgeon and senior colleague, and foetal
monitoring to influence decision-making.
c) What are the early symptoms and signs of a spinal block that is
ascending too high?
T1-T4 block:
● Weak cough, shortness of breath (paralysis of intercoastal muscles).
● Hypotension and bradycardia (cardiac sympathetic block).
● Nausea and vomiting.
● Foetal compromise.
C6-C8 block:
● Paraesthesia of hands and arms.
C3-C5 block:
● Desaturation and respiratory arrest (diaphragmatic paralysis).
● Brainstem involvement and intracranial spread:
- a difficulty in phonation and swallowing;
- loss of consciousness.
d) How should you manage a patient who complains of pain
during an elective caesarean section under spinal anaesthesia?
● Stop surgery if required.
● Reassure.
● Communication with the mother and surgeon.
● Offer analgesia.
● Entonox®.
● Intravenous opioid:
- 25-50mg fentanyl, repeat as necessary;
- inform the neonatologist if this is given before delivery of the baby.
● Surgical infiltration of local anaesthetic.
● Epidural opioid/LA.
● General anaesthesia.
Categories of section
Category 1.
Immediate threat to the life of the woman or fetus
(for example, suspected uterine rupture,
major placental abruption,
cord prolapse, fetal hypoxia or
persistent fetal bradycardia).
Perform category 1 caesarean birth as soon as possible, and in most situations within 30 minutes of making the decision
Category 2. Maternal or fetal compromise which is not immediately life-threatening.
Perform category 2 caesarean birth as soon as possible, and in most situations within 75 minutes of making the decision.
Category 3. No maternal or fetal compromise but needs early birth.
Category 4. Birth timed to suit woman or healthcare provider.
Q4 — Intrauterine foetal death
A woman, who has had an intrauterine foetal death (IUFD) at 36 weeks’
gestation in her first pregnancy, is admitted to the delivery suite for
induction of labour.
a) List the causes of IUFD.
Antepartum:
● Congenital malformation.
● APH.
● Pre-eclampsia/eclampsia.
● Maternal diabetes mellitus.
Intrapartum:
● Abruptio placentae.
● Severe maternal or foetal infection.
● Cord prolapse.
● Uterine rupture.
b) Describe the important non-clinical aspects of her
management.
● Psychological distress needs to be addressed.
● One-to-one midwifery care.
● Care provided in a quiet room.
● Free access to family members if the mother wishes.
● Pain relief options to be discussed by an anaesthetist.
● May require HDU care.
c) What are the considerations when providing pain relief for this
woman prior to delivery?
Patient factors:
● Address psychological distress.
● Consider pre-existing comorbidities.
● Sepsis.
● Coagulopathy.
Obstetric factors:
● Cause of IUFD.
● Mode of delivery:
- early induction of labour;
- may require a caesarean section.
Others:
● One-to-one midwifery care.
● MEOWS charting.
● May require HDU care.
● Consider sedation.
d) What are the options for pain relief?
d) What are the options for pain relief?
● Entonox®.
● Parenteral opioids — diamorphine/pethidine IM, morphine/fentanyl/
remifentanil PCA.
● Supplementary regular IV/oral paracetamol.
● Regional anaesthesia with epidural PCEA — if not contraindicated
e) If this patient requires a caesarean section what are the
advantages of using regional anaesthesia, other than the
avoidance of the effects of general anaesthesia?
● Good postoperative analgesia.
● Early mobilisation.
● Decreased risk of PPH.
● Decreased risk of DVT.
● Fewer drugs — less chance of anaphylaxis and drowsiness.
Q5 — Obesity and pregnancy
A primiparous patient with a BMI of 55kg/m2 presents in the high-risk
anaesthetic antenatal assessment clinic at 34 weeks’ gestation. She is
hoping to have a normal delivery.
a) What are the specific cardiorespiratory effects of obesity in the
pregnant patient?
Cardiovascular system:
● Increase in stroke volume, heart rate, and increased pulse pressure
associated with pregnancy may be poorly tolerated.
● Hypertension, ischaemic heart disease and congestive heart failure.
● Exaggerated response to aortocaval compression due to increased
intra-abdominal fat.
● Peripartum cardiomyopathy.
Respiratory system:
● Decrease in FRC associated with normal pregnancy is aggravated.
● Postoperative hypoxia and atelectasis.
● Obstructive sleep apnoea.
● Pulmonary hypertension and cor pulmonale.
● Restrictive respiratory pattern.
b) What are the specific obstetric concerns associated with a
raised BMI in pregnancy?
Increased risks of:
● Gestational DM, PIH, pre-eclampsia.
● Thromboembolic disorders.
● Instrumental and caesarean delivery.
● Postpartum haemorrhage.*
● Postoperative infections (surgical wound and chest infections).**
● Peripartum cardiomyopathy.**
c) What are the foetal risks associated with a high BMI?
Increased risks of:
● Miscarriage, preterm birth, still birth.**
● Meconium aspiration.
● Foetal distress.**
● Shoulder dystocia.**
● Neural tube defects, macrosomia.**
● Low Apgar score.**
● A higher incidence of neonatal intensive care admissions.
d) What are your anaesthetic concerns in this obstetric patient
with a high BMI?
● Difficult intravenous access.
● Difficulty performing neuraxial techniques
and a high risk of dural puncture.
● A higher incidence of failed blocks due to altered spread of LA
secondary to fat deposition in the epidural space.
● Risks with GA:
- difficult airway;
- risk of aspiration;
- short apnoea time due to decreased FRC
and increased oxygen consumption; - increased oxygen requirements postoperatively.
● Equipment issues and staff:
- maximum weight supported by operating table;
- risk to staff involved in manual handling;
- longer spinal and epidural needles;
- larger BP cuffs, TEDs, Flowtron®;
- US for venous access, arterial and central venous cannulation.
e) What are your considerations when you provide labour
analgesia?
● Review of antenatal consultation notes with obstetric anaesthetist.
● Difficult IV access.
● Early epidural to allow time for a difficult procedure.
● US scan of the back to facilitate epidural insertion.
● Supplemental analgesia with Entonox® and oral/IV paracetamol.
● Analgesic options in the case of a failed epidural —
remifentanil/fentanyl PCA.
● If opioids are used, supplemental oxygen, pulse oximetry and one-to one
midwifery care is needed.
Q6 — Surgery in pregnancy
A 28-year-old woman presents for an acute appendicectomy under general
anaesthesia; she is 22 weeks pregnant.
a) List the risks to the foetus during anaesthesia in this situation
● Spontaneous abortion.
● Preterm labour.
● IUGR.
● Foetal death.
● Placental ischaemia and foetal hypoxia.
● Foetal acidosis/ion trapping and myocardial depression.
● Teratogenicity in the first trimester.
b) How can the risks to the foetus be minimised?
● Timing of surgery.
● Avoid foetal hypoxia.
● Prevention of preterm labour.
● Consider the effects of anaesthetic drugs on the foetus.
c) How does timing the surgery reduce the foetal risk?
● Elective surgeries to be postponed at least
6 weeks postpartum, if possible.
● Alternatively, delay surgeries into the
second trimester to avoid the
teratogenic effects of drugs.
e) List any four drugs used in anaesthetic practice and their
adverse effects on the foetus.
● Ketamine increases uterine tone and vasoconstriction
in the first two trimesters.
● NSAIDs in the third trimester cause closure of the ductus arteriosus.
● Nitrous oxide interferes with DNA synthesis.
● Single-dose opioids and benzodiazepines are safe.
Long-term use causes withdrawal when the foetus is delivered.
f) What additional preoperative and intraoperative steps would
you take to ensure foetal safety if she is 27 weeks pregnant
instead
The foetus is viable as it is at 27 weeks’ gestation.
Preoperatively:
● Discussion with the obstetric team to plan for preterm labour and
delivery.
● Discussion with paediatricians/PICU.
● Consider steroids for lung maturation.
● FHR and FHR variability monitoring. FHR variability is observed from
25 weeks onwards.
● CTG monitoring preoperatively and postoperatively.
Intraoperatively:
● The physiological effects of pregnancy may be more pronounced.
● The presence of obstetricians/midwife on site.
d) What steps would you take to avoid foetal hypoxia?
● Avoid maternal hypoxia:
- adequate pre-oxygenation
- anti-aspiration prophylaxis;
- RSI.
● Maintain maternal haemodynamic stability.
● Avoid maternal hypocapnia and hypercapnia
(maintain PaCO2 around 4kPa):
- hypocapnia causes placental vasoconstriction;
- hypercapnia decreases the transfer of CO2 from the foetus to the
mother across the placental barrier, causing foetal acidosis.
● Avoid hypovolaemia and anaemia.
● Light planes of anaesthesia increase catecholamine secretion —
placental vasoconstriction and hypoperfusion.
● Effective postoperative analgesia —
pain causes placental
vasoconstriction and foetal hypoxia.
● Detection and suppression of premature labour with tocolytics.
a) What factors may contribute to difficulties encountered when
securing the airway under general anaesthesia in the pregnant
patient?
Obstetric factors:
● Decreased FRC and increased oxygen consumption —
decreases the safe apnoea time.
● Increased weight gain, large breasts —
difficult laryngoscopy.
● Airway oedema —
a smaller-sized ETT may be required.
● Increased vascularity of the mucosa —
bleeding on airway instrumentation.
● High risk of aspiration.
Human factors:
● Cognitive load — concerns for mother and baby.
● Time restrictions — often an emergency situation.
● Declining frequency of obstetric GA.
Technical factors:
● Remote location of obstetric units.
● Poor access to the airway under the drapes.
● Misplaced cricoid pressure.
b) What measures can be taken to reduce airway-related
morbidity and mortality associated with general anaesthesia in
a pregnant woman?
● Assessment of the airway.
● Identify senior help and call for help early.
● Mark the cricothyroid membrane and
call for surgical help if a difficulty is anticipated.
● Adequate pre-oxygenation —
3-4 minutes of tidal breathing or 4-5
vital capacity breaths.
● Ramped up position —
tragus in line with or above the sternal notch.
● Apnoeic oxygenation.
● Anti-aspiration prophylaxis.
● Training staff to be familiar with the
Difficult Airway Society (DAS) guidelines.
● Multidisciplinary team briefing with regard to
waking up the patient
or not after a failed intubation is declared.
c) What are the recommendations in the 4th National Audit
Project (Major Complications of Airway Management in the UK,
NAP4) regarding airway management in the pregnant woman?
Obstetric anaesthetists to maintain airway skills including a
difficult/failed intubation and CICV.
● Anaesthetists to be familiar and skilled with rescue secondgeneration
supraglottic airway devices (SADs).
● Department to provide skills and equipment to deliver AFOI
whenever it is needed.
● All staff in the recovery area of a delivery suite must be competency
trained; skills to be regularly updated.
Q8 — Mitral stenosis in pregnancy
A 27-year-old woman is 13 weeks pregnant. In the antenatal clinic she is
found to have an asymptomatic heart murmur. A subsequent
echocardiogram shows moderate to severe mitral stenosis.
a) List the causes of mitral stenosis (MS).
● Rheumatic heart disease.
● Congenital.
● Diseases affecting multiple systems, e.g. sarcoidosis.
● Infiltrating diseases
b) What are the echocardiographic criteria for the diagnosis of
severity of MS?
Mitral stenosis is classified as per:
● Valve area:
- mild MS — 1.6-2cm2;
- moderate MS — 1.5-1cm2;
- severe MS — <1cm2.
● Pressure gradients across the valve:
- mild MS — <5mmHg;
- moderate MS — 6-10mmHg;
- severe MS — >10mmHg.
c) What is the normal mitral valve area and at what point does the
patient become symptomatic with MS?
● Normal area = 4-6 cm2.
● The patient becomes symptomatic at a valve area <2cm2.
d) What are the cardiovascular changes in pregnancy that could
exacerbate the pathophysiology of MS?
● Increase in heart rate.
● Increased cardiac output.
● Blood volume increases.
● Decreased systemic vascular resistance.
● Pain and anxiety in labour further increase cardiac output.
● Autotransfusion during the second stage.
e) How do the cardiovascular changes in pregnancy exacerbate
the pathophysiology of MS?
● Mitral stenosis underfills the left ventricle causing pressure and
volume overload in the pulmonary circulation.
Tachycardia of pregnancy decreases diastolic filling time,
further decreasing left ventricular filling,
increases pulmonary pressures causing pulmonary
congestion.
Pulmonary oedema can develop with AF.
● The fixed cardiac output state of MS results in a worsening of pressure
through the pulmonary circulation and into the right heart.
● Increased blood volume of pregnancy increases preload and
exacerbates pulmonary oedema.
● Because the cardiac output is fixed,
any decrease in systemic vascular
resistance decreases the coronary perfusion pressures.
● The risk of decompensation depends on severity.
Anything worse than moderate disease (valve area <1.5cm2)
frequently results in heart failure,
which usually develops in the second or third trimester
and is progressive.
f) What are your cardiovascular goals when she presents in
labour?
● Control of rate and rhythm:
- avoid tachycardia;
- avoid a rapid ventricular response in AF.
● Maintain afterload.
● Avoid an increase in preload.
● Avoid hypoxia, hypercarbia and acidosis as they exacerbate
pulmonary hypertension.
g) Outline your management of this patient in labour.
● Early epidural to avoid sympathetic stimulation.
● Establishment of a block gradually to avoid precipitous hypotension.
● Use of alpha-agonists to treat hypotension.
● Nitrous oxide increases pulmonary vascular resistance.
● Assist second stage to cut short labour and limit Valsalva manoeuvre.
● Caution with oxytocin as it decreases SVR and increases PVR.
● Ergometrine is contraindicated as it is a pulmonary vasoconstrictor.
h) Explain the mechanism of pulmonary oedema post-delivery.
A sudden increase in preload due to:
● Autotransfusion due to uterine contraction.
● Decompression of the IVC.
A 39-year-old multiparous woman is admitted post-term with spontaneous
rupture of membranes and meconium-stained liquor. After an epidural
catheter is inserted, a syntocinon infusion is started as she is in early labour.
She started contracting shortly and the foetal heart rate drops. She
becomes breathless and cyanosed; her blood pressure has dropped.
a) What are the differential diagnoses for this presentation?
Obstetric causes:
● Amniotic fluid embolism.
● Uterine rupture.
● Eclampsia.
● Placental abruption.
● Acute haemorrhage.
● Cardiomyopathy.
● Uterine inversion.
Non-obstetric causes:
● Pulmonary embolism.
● Air or fat embolism.
● Tension pneumothorax.
● Anaphylaxis.
● High spinal/epidural, local anaesthetic toxicity.
● Pulmonary oedema, heart failure, myocardial infarction.
● Sepsis.
● Transfusion reaction.
● Aspiration.
● Respiratory condition exacerbation.
● Intracranial bleed.
b) What are the risk factors for an amniotic fluid embolism (AFE)?
● Induction of labour by any method.
● Use of oxytocin.
● Assisted delivery (forceps/ventouse) or caesarean section.
● Maternal age >35 years.
● Multiple pregnancy.
● Polyhydramnios.
● Eclampsia.
● Uterine rupture.
● Cervical trauma.
● Placenta praevia.
● Placental abruption.
● Ethnic minority.
c) Describe the pathogenesis of AFE
Exposure of maternal circulation to amniotic fluid
or foetal antigens is a prerequisite.
● There are two main theories —
mechanical and immune-mediated.
● Anaphylactoid syndrome.
● Phase 1 — lasts 30 minutes, entry of amniotic fluid into the
circulation, the pulmonary artery pressure rises, right ventricular
failure, microvascular damage, hypotension. Microthrombi are
formed once DIC develops.
● Phase 2 — left ventricular failure, endothelial activation and leakage,
leading to DIC
d) What are the clinical features of AFE?
● Hypotension and foetal distress are identified in all cases of AFE.
● Sudden cardiovascular collapse or cardiac arrest.
●Cyanosis, dyspnoea, seizures, coagulopathy,
pulmonary oedema, ARDS.
● Uterine atony, bronchospasm, cough, headache, chest pain.
e) How would you diagnose AFE?
● Clinical symptoms once other causes are ruled out.
● Postmortem — foetal squames or hair in lungs.
f) What is the incidence of AFE?
● 1.7 per 100,000 pregnancies.
● The case fatality is 19%.
● 120 cases between 2005 and 2014; UKOSS register.
● Fifth direct cause of maternal mortality (MBRRACE-UK report).
g) List the management strategies for AFE.
Supportive management depending on the clinical presentation:
● Senior clinicians should be involved, teamwork,
urgent decision to deliver,
need for critical care support.
● Advanced Life Support® guidelines — ABC.
● Haemorrhage control.
● Coagulation abnormalities to be corrected; involve the senior
haematology consultant
a) Describe the pain pathways associated with the first and
second stages of labour.
**
● The first stage of labour:
pain from the uterus,
lower uterine segment
and vagina is transmitted via sensory fibres which accompany
sympathetic nerves and ends in the dorsal horns of T10-L1.
● The second stage of labour:
afferent nerves innervating the vagina
and perineum travel via the pudendal nerve
to dorsal root ganglia of S2-S4.
b) Explain how and why the nature of the pain experienced
changes as labour progresses.
● The first stage of labour: visceral pain,
which is poorly localised and
diffuse in nature.
● Pain is felt in the lower abdomen and lumbosacral area.
● The second stage of labour:
somatic pain, which is better localised.
c) What dermatomes should be blocked for labour analgesia and
a lower segment caesarean section (LSCS)?
● Labour analgesia — T10-S5.
● LSCS — T4-S5.
d) Why is it essential to achieve a higher dermatomal level of
regional block for a caesarean section than for analgesia in
labour?
A higher level of block is required for LSCSs — due to peritoneal traction
e) Why do you sometimes observe bradycardia during regional
anaesthesia for a caesarean section?
● Parasympathetic over-activity due to spinal sympathetic block.
● Decreased venous return triggers the
Bainbridge reflex and Bezold-
Jarisch reflex.
● Blockade of cardio-accelerator fibres from T1-T4.
● Surgical manoeuvres, e.g. exteriorising the uterus.
f) List any five specific situations in which labour epidurals may be
beneficial.
**
● Pre-eclampsia (without severe thrombocytopenia or coagulopathy).
● High Body Mass Index (BMI).
● Anticipated difficult airway or other risk factors for a general
anaesthetic.
● High risk for assisted vaginal delivery,
e.g. breech or multiple gestation.
● Trial of labour after a previous caesarean section.
● Maternal cardiovascular, cerebrovascular or respiratory disease
g) What is puerperal sepsis?
**
Puerperal sepsis is infection of the genital tract occurring at any time
between rupture of membranes or labour and the 42nd day postpartum
associated with two or more of the following:
● Pelvic pain.
● Fever, abnormal vaginal discharge.
● Abnormal smell of discharge.
● Delay in reduction in the size of the uterus.
h) Name the organisms implicated in sepsis in the UK.
● Group A Streptococcus.
● Streptococcus pneumoniae.
● Escherichia coli.
● H1N1 influenza virus.
i) List the risk factors for sepsis
Obstetric factors:
● During pregnancy:
- amniocentesis;
- cervical suture.
● During vaginal delivery:
- prolonged rupture of membranes;
- prolonged labour;
- vaginal trauma;
- surgical procedures — episiotomy, caesarean section;
- retained products.
Non-obstetric factors:
● Obesity.
● Diabetes.
● Immunosuppression.
● Anaemia.
● Socioeconomic deprivation.
● History of pelvic inflammatory disease.
BJA Obesity article
Key Points
- Maternal obesity is increasing worldwide and is associated with adverse outcomes for both mother and baby.
- Multidisciplinary team involvement is vital for managing the parturient with obesity.
- Neuraxial analgesia should be offered early in labour.
*Continuous neuraxial techniques are optimal for Caesarean delivery.
- General anaesthesia poses significant risk in these high-risk patients
Maternal complications
Gestational diabetes
Gestational HTN PET
OSA
CVS
VTWE
Infection + Sepsis
Instrumental Delivery
+ Failed
Section
PPH
LOS
BJA Extra points
Logistics
Analgesia
- Logistical planning
Women with obesity should only have their baby delivered in obstetric units that have services adequate to meet their
including staffing, equipment and accessibility
consultant-led unit with appropriate anaesthesia and neonatal services
Specialised anaesthetic equipment should be readily available, such as difficult airway equipment, US machines, long spinal and epidural needles,
t. An NIBP cuff on the forearm may be used if it is not possible to use an appropriately sized blood pressure cuff on the upper arm.7
Even with appropriate equipment, transporting women with BMI >50 kg m−2 to the operating theatre in the event of an emergency can be challenging
- Neuraxial
They provide the most effective analgesia with the fewest adverse effects for both mother and baby. Furthermore, with neuraxial techniques, labour analgesia can be readily converted to surgical anaesthesia should the need for CD arise,
accidental dural puncture (ADP) compared with patients of normal BMI (4% vs 1%
An ITC can also be placed to provide continuous labour analgesia. Whilst placement of an ITC is usually only considered after inadvertent ADP, elective placement in women with BMI >50 kg m−2 may be an option for neuraxial analgesia,
- Other analgesia
Inhaled nitrous oxide and oxygen
Opioids should be judiciously used in parturients with obesity because the incidence of OSA and the risk of respiratory depression are both increased.
Accupuncture and transcutaneous electrical nerve stimulation, could also be considered
BJA Extra points
Logistics
Analgesia
- Logistical planning
Women with obesity should only have their baby delivered in obstetric units that have services adequate to meet their
including staffing, equipment and accessibility
consultant-led unit with appropriate anaesthesia and neonatal services
Specialised anaesthetic equipment should be readily available, such as difficult airway equipment, US machines, long spinal and epidural needles,
t. An NIBP cuff on the forearm may be used if it is not possible to use an appropriately sized blood pressure cuff on the upper arm.7
Even with appropriate equipment, transporting women with BMI >50 kg m−2 to the operating theatre in the event of an emergency can be challenging
- Neuraxial
They provide the most effective analgesia with the fewest adverse effects for both mother and baby. Furthermore, with neuraxial techniques, labour analgesia can be readily converted to surgical anaesthesia should the need for CD arise,
accidental dural puncture (ADP) compared with patients of normal BMI (4% vs 1%
An ITC can also be placed to provide continuous labour analgesia. Whilst placement of an ITC is usually only considered after inadvertent ADP, elective placement in women with BMI >50 kg m−2 may be an option for neuraxial analgesia,
- Other analgesia
Inhaled nitrous oxide and oxygen
Opioids should be judiciously used in parturients with obesity because the incidence of OSA and the risk of respiratory depression are both increased.
Acupuncture and transcutaneous electrical nerve stimulation, could also be considered
Peripartum anaesthetic management: CD
neuraxial anaesthesia or GA has been chosen as the primary anaesthetic, all patients with obesity should be placed in the ‘ramped position’ with left uterine displacement
Retraction of the panniculus may be needed for adequate exposure for surgery especially when Pfannenstiel incision is used. Many obstetricians choose to tape the panniculus in the cephalad direction.
Cephalad retraction is associated with aortocaval compression that can lead to maternal hypotension and non-reassuring fetal heart tones
Obesity is a risk factor for surgical site infection after CD.
Advancing a Tuohy needle may be technically easier, and once the epidural space has been located, it can be used as an introducer for the long spinal needle as part of a needle-through-needle CSE technique
More commonly, catheter-based techniques are chosen to deliver extended neuraxial anaesthesia for CD. If a patient has a labour epidural catheter in situ,
General anaesthesia
There are significant risks associated with GA for parturients who are obese. The importance of patient positioning, preoxygenation, presence of adequate personnel and difficult airway equipment cannot be emphasised enough
However, it is advised that lean body weight should be used to calculate initial doses of i.v. induction agents rather than total body weight
By contrast, suxamethonium should be dosed to total body weight because of increased circulating plasma cholinesterase. If non-depolarising neuromuscular blocking drugs are being used on induction of anaesthesia, these should be given based on ideal body weight
as the risk of aspiration exists during this time as well. To minimise risk, the stomach should be decompressed with an orogastric tube and the patient should be awake, obeying commands and able to protect her airway before tracheal extubation. .
ried out with the patient in the head-up position to allow control of the airway and improve respiratory mechanics. If the parturient has OSA, it is advised to commence CPAP immediately to avoid airway obstruction and hypoxia
Maternal Critical Care
Peripartum women should receive high-quality critical care provision irrespective of their location.
Close working between the critical care and maternity teams is essential.
Checklists and local standard operating procedures can be helpful when a maternity patient is admitted to critical care.
Every effort should be made to keep mother and baby together.
Women can sustain psychological injury through birth trauma and critical illness.
Maternal Critical care checklists
Within 1 h
Alert poster
Airway alert poster
Obs consultant
CMM
Neonatal resuscitaire in unit
Delvery pack and crash section trolley
Maternal Critical care checklists
Within 12h
Consultant bedside review
fetal compromise
?need for fetal monitroing
involve link midwife
Medical speciality referall?
Surgical review
Crit care pharmacy
CC dietician
NOK
Proteinuria?
Breastfeeding review
During crit care
Senior clinician review
Psychology referall?
Midwifery input
Contact mother baby
breast milk expression as desired
Equipment
Intubation
Short handled laryngoscope
Sodium citrate
Ramp (e.g. Oxford pillow)
Birth/review
Neonatal resuscitation equipment
Caesarean section equipment tray
Speculum
Uterotonic drugs
(oxytocin, ergometrine, carboprost, misoprostol)
Fetal assessment Fetal Doppler
Breastfeeding & psychological care Breast pump
iPad (FaceTime)
Patient/baby diaries
Digital or instant camera/memory card
Challenges airway breathing
Aspiration –
assume a full stomach even if starved H2RA or PPI i.v. in anticipation
Aspirate nasogastric tube (if in situ)
Sodium citrate 0.3 M solution –
give 30 mmol immediately before induction
Head-up tilt
Cricoid pressure
Limit any facemask ventilation to non-excessive pressures using airway adjuncts as required
Desaturation – decreased FRC, increased oxygen consumption
Consider high flow humidified nasal oxygen for preoxygenation (CAUTION – worsens aerosol generation if concerns of infection)
Modify RSI to include manual ventilation with cricoid pressure in respiratory failure
Difficult intubation Follow OAA-DAS guideline and make a plan for failed intubation and failed oxygenation
Ensure appropriate equipment including short handled laryngoscope
Ensure optimal positioning including ‘ramp’ for patients with high BMI
Ensure appropriate help and difficult airway equipment available
Intracerebral haemorrhage – stimulatory effects of direct laryngoscopy (pre-eclampsia)
Ensure BP well controlled before induction and modify RSI to use fast onset opioid (e.g. alfentanil) as a coinduction agent
yngeal oedema If laryngeal oedema is present then a smaller endotracheal tube may be required.∗
Aortocaval compression (pregnant) Ensure manual displacement or left lateral tilt in place when patient is supine
Vasopressor/vagolytic drugs immediately available
Circulatory support
he first intervention for any new episode of maternal hypotension should be to exclude aortocaval compression by using the full left lateral decubitus position
. The onset of supine hypotension may be delayed and nausea is a common warning sign.
Vasopressor drugs alter uterine blood flow but this risk is outweighed by the requirement to resuscitate the mother. Invasive monitoring is essential as severe sudden increases in blood pressure can increase the risk of placental abruption.
Noradrenaline (norepinephrine) is recommended as the first-line agent.15 Arginine vasopressin is uterotonic and is consequently not used first line in pregnancy.
Adrenaline (epinephrine) is tocolytic and can cause fetal dysrhythmias, but its use in pregnancy is well established for resuscitation.
Drugs
Both propofol and midazolam infusions are used, though midazolam can cause neonatal withdrawal if used for extended periods of time. Dexmedetomidine has also been used successfully but toxicity has been reported in animal studies: it can be used after a risk-benefit assessment
Neuromuscular blocking agents do not cross the placenta in significant amounts.
Paracetamol is safe to use. Non-steroidal anti-inflammatory drugs should be avoided after 30 weeks of gestation (they cause closure of the ductus arteriosus). Codeine phosphate should be avoided in breastfeeding because of unpredictable maternal metabolism and overdose risk in the infant; dihydrocodeine can be used with caution.
t are associated with respiratory depression in the neonate and as with midazolam there is a risk of neonatal withdrawal after prolonged usage
Imaging
Care bundles
t. A CT scan of the pelvis typically results in a fetal dose of 10–50 mGy, which is not associated with miscarriage or teratogenesis, but there may be a small increased risk of malignancy.
Care bundles and nutrition
Pregnancy confers an additional risk of thromboembolic disease (over and above critical illness) extending for 6 weeks after
Conventional care bundles for stress ulcer prophylaxis and prevention of ventilator-associated pneumonia should be used. Both proton pump inhibitors (PPIs) and histamine-2 receptor antagonists (H2RAs)
The relative energy, protein and micronutrient requirements are altered, and depend on gestation and underlying illness. The readily available ‘complete’ enteric feeds are not tailored to pregnant women. Expert advice from a dietician is recommended.
The fetus
absence of a specific obstetric indication, continuous cardiotocography (CTG) monitoring is not used outside of labour, but it is common for obstetricians to operate a twice-daily routine CTG assessment when women have been admitted to critical care
CTG trace may also be indicative of compromised maternal physiology and optimisation of the mother can improve fetal physiology
Where fetal distress does not resolve, delivery needs to be arranged as an emergency, but should not endanger the life of the mother. In the meantime, fetal resuscitation should be undertaken:
1.
Stop oxytocin infusion (if in progress)
2.
Full left lateral decubitus position
3.
Tocolysis (terbutaline or glyceryl trinitrate spray)
4.
Improve cardiac output, correct hypotension – fluid bolus ± vasoactive agent
5.
Increase oxygen tension at placenta – give oxygen
ICU Delivery
1.
Environment: large side room
2.
Personnel: neonatal, obstetric and midwifery team aware of the patient’s location
3.
Equipment: specified by the neonatal and obstetric teams and may include: CTG monitor, Caesarean tray, neonatal resuscitation kit ± Resuscitaire
4.
Drugs: uterotonic drugs must be available
Maternal Critical Care
Specific conditions
Multiple comorbidities in pregnant women can be more challenging to manage in critical illness.
Close working between the critical care, other specialist, and maternity teams is essential.
Maternal admissions to critical care result most frequently from major obstetric haemorrhage, sepsis, and pre-eclampsia.
Non-obstetric causes of deterioration should always be considered.
Causes for obstetric haemorrhage—‘the 4 Ts’
Tone
Uterine atony
Haematoma
Trauma
Laceration
Inversion, uterine rupture, or both
Tissue
Retained tissue
Invasive placenta
Thrombin
Coagulopathy
Uterotonic drugs used in PPH.
- Oxytocin
Syntocinon
2.Ergot alkaloids
- Prostaglandin analogues
- Oxytocin
5 U i.v. or i.m.
Myometrial contraction
Onset within 1 min i.v. (4 min i.m.). May be repeated to total 10 U followed by infusion (e.g. 40 U over 4 h)
Causes transient hypotension, arrhythmias, and nausea. Structurally similar to antidiuretic hormone: causes water retention and hyponatraemia
2.Ergot alkaloids
Ergometrine
250–500 μg i.m.
I.V. injection slowly with caution
Vasoconstriction and myometrial contraction
Highly emetogenic—give antiemetic.
Causes hypertension (can be severe),
coronary vasospasm, and pulmonary hypertension.
Avoid in PET, hypertension, coronary disease, aortopathies, aneurysms
- Prostaglandin analogues
- Carboprost (e.g. Hemabate) 250 μg i.m.
Prostaglandin F2α agonist:
myometrial contraction
May only be given i.m. Dose of 250 μg may be repeated eight times at 15 min intervals.
Prostaglandin analogues can cause bronchospasm but may be given in asthma with atonic bleeding because of threat to life. Cause severe diarrhoea, hyperthermia, rash, dizziness
___________________________________
- Misoprostol
600 μg per rectum
Prostaglandin E1 agonist: myometrial contraction and cervical relaxation See note above regarding unwanted effects in prostaglandin analogues
MOH
Risk increased
Normal losss
MOH?
Uterine blood flow at term is 600–900 ml min−1. Uncontrolled bleeding from the uteroplacental bed is the commonest cause of maternal death worldwide and it is the most frequent obstetric reason for admission to critical care
Emergency Caesarean section,
prolonged labour,
multiple pregnancy,
polyhydramnios, macrosomia, obesity, intrapartum sepsis, and uterine inversion are all associated with an increased risk
Blood loss of ≤500 ml after a vaginal delivery or ≤1000 ml after Caesarean section is considered normal.
f MOH and while a loss of ≥1500 ml is commonly suggested for convenience
If drugs fail
Uterine-preserving interventions include
arterial ligation,
B-Lynch compression sutures,
uterine packing and
uterine balloon tamponade.
Timely hysterectomy should be performed if necessary to save life
MOH is anticipated (morbidly adherent placenta) prophylactic bilateral placement of arterial balloon catheters before Caesarean section may be uterus-preserving
Resuscitative endovascular balloon occlusion of the aorta (REBOA) does not require radiological expertise
Sepsis
The physiology of normal pregnancy and response to labour may mask the presence of sepsis. Intrapartum, women may be tachypnoeic with increases in temperature, white cell count, and lactate even in the absence of infection. Assessment by the multidisciplinary team (MDT) with close attention to physiological trends and a high index of suspicion. Delirium is an ominous sign in maternal sepsis; it is seen infrequently in the labour suite and may be misdiagnosed as puerperal psychosis.
‘Maternal sepsis is a life-threatening condition defined as organ dysfunction resulting from infection during pregnancy, childbirth, post-abortion, or postpartum period.
The maternal sepsis bundle should be initiated without delay
Fluid resuscitation of 30 ml kg−1 may be deemed excessive, especially peripartum, as the maternal circulation is vulnerable to fluid overload. Reassessment after each 500 ml is prudent
t. Special care should be applied in the context of comorbid PET. Vasopressor therapy may be needed concurrently with resuscitation with i.v. fluids. Noradrenaline (norepinephrine) is the first-line agent. A target MAP of ≥65 mmHg applies to non-pregnant patients, but is nevertheless a reasonable starting point
Obstetric infections are usually polymicrobial and initial antimicrobial therapy must cover both Group A Streptococcus and E. coli
bstetric sites of infection include retained products of conception, chorioamnionitis, endometritis, pelvic abscess, and wound infection
PET
new-onset hypertension after 20 weeks’ gestation associated with proteinuria, evidence of end-organ involvement, or utero-placental dysfunction
. A protein-creatinine ratio of ≥30 mg mmol
PET can rapidly progress from a ‘mild’ condition to one with severe end-organ
A diagnosis of ‘PET with severe features’ is made if the patient has a systolic BP (SBP) ≥160 mmHg or any of the following features: cerebral involvement (e.g. headache, visual disturbance, or altered mental state), an otherwise unexplained severe right upper quadrant pain, serum transaminases more than twice the normal limit, platelets less than 100×109 L−1, progressive renal insufficiency, or pulmonary oedema.
PET RX
The treatment of PET is delivery of the placenta. It should be noted that PET is frequently diagnosed after birth and can persist and worsen initially before resolvin
Supportive measures
In the context of PET, a BP of 160/110 mmHg is an obstetric emergency. The goal of treatment is to aim for a SBP of <140 mmHg: it is systolic pressure that is associated with adverse endpoints such as intracerebral haemorrhage. SBP≥180
symptoms such as headache may be seen as BP improves. Infusion of an antihypertensive agent is usually considered an indication for invasive monitoring of arterial BP
PET RX
The treatment of PET is delivery of the placenta. It should be noted that PET is frequently diagnosed after birth and can persist and worsen initially before resolvin
Supportive measures
In the context of PET, a BP of 160/110 mmHg is an obstetric emergency. The goal of treatment is to aim for a SBP of <140 mmHg: it is systolic pressure that is associated with adverse endpoints such as intracerebral haemorrhage. SBP≥180
symptoms such as headache may be seen as BP improves. Infusion of an antihypertensive agent is usually considered an indication for invasive monitoring of arterial BP
Antihtn in PET
Hydralazine
Y Y
Maternal hypotension and tachycardia.
Adequate hydration before administration is important
Labetalol Y Y Y Nausea (4.1%)
Dizziness (4.1%)
Nifedipine MR Y
Headache (5.4%), maternal tachycardia (4.1%), dizziness (2.7%)
PET emergencies—therapeutic options and considerations
Pulmonary oedema
Conventional supportive management including oxygen, diuretics and where necessary CPAP
Once stabilised expedite delivery
Neuraxial anaesthesia preferable where possible Most cases of PET pulmonary oedema are postpartum
Differential diagnoses:
- Acute coronary syndrome (e.g. related to spontaneous coronary artery dissection)
- Peripartum cardiomyopathy
- Overzealous fluid administration (common)
- Tocolytic use
- Lung injury (e.g. transfusion/infection/ARDS)
Hypertensive encephalopathy:
*
Cerebral oedema
*
Intracranial haemorrhage
Supportive management and urgent optimisation of BP control
Magnesium infusion as eclampsia prophylaxis in all symptomatic PET
Cortical blindness is managed by controlling and optimising the BP
Differential diagnoses: metabolic abnormalities, drugs, infection, and cerebral venous sinus thrombosis
Eclampsia A 4 g loading dose of magnesium sulphate (MgSO4) followed by an infusion 1–2 g i.v.a
aAKI: halve the infusion dose.
Give additional bolus of MgSO4 should the woman have a fit while on MgSO4.
If refractory to MgS04 give antiepileptic drugs (e.g. benzodiazepines, levetiracetam) 1% Risk of recurrence of eclampsia in a future pregnancy
Subcapsular liver rupture Stabilise and contact nearest liver unit Subsequent pregnancies are infrequently complicated by HELLP (2–19%)
