11. Obstetrics Flashcards
- While performing a lumbar epidural using a loss of resistance to saline (LORS) technique, you disconnect the syringe from the Tuohy needle to find there is clear fluid very obviously dripping from the needle. What is the best way to confirm whether this fluid is cerebrospinal fluid (CSF)?
A. Observe rate and duration of fluid dripping
B. Assess temperature of fluid with back of gloved hand
C. Dipstick fluid to determine specific gravity
D. Send for beta 2 transferrin assay
E. Dipstick fluid to test for glucose
- E
The danger of accidental dural puncture is such that the anaesthetists must be able to diagnose
whether it has occurred or not, when suspected by fluid dripping out of the needle.
Further, the diagnosis needs to be made quickly at the bedside to inform ongoing management of
the patient and to decide whether a spinal catheter is indicated.
In this scenario the fluid will either be cerebrospinal fluid or saline 0.9% used in the loss of resistance
syringe. It is possible to distinguish the two substances by comparison of temperature (subjectively
reported using a gloved hand), protein, or glucose estimation on dipstick testing, and by measuring
pH value. Cerebrospinal fluid typically will be warm, contain glucose and protein, and have a pH
greater around 7.4. ‘Normal’ saline is relatively acidotic with pH 7.0. Rarely saline may test positive
for protein or glucose if it has been contaminated by blood.
Assessing temperature of the fluid may be a reliable way to distinguish the two liquids but is subject to variables such as ambient, patient, and operator temperature, etc. An objective test is more reliable than this subjective one.
Therefore the best answer in this scenario is dipsticking to test for glucose.
Estimation of free flow rate alone has been shown to be unreliable as a means of distinguishing the
two fluids.
Properties of CSF
Specific gravity .006– .008
Opening pressure 90– 80 mmH2O
pH 7 28– 7.32
Na 35– 50 mmol/ L
Cl 6– 27 mmol/ L
Glucose 45– 80 mg/ dL
Beta 2 transferrin assay is the gold standard test for CSF. This specialized test is carried out in only a
few centres in the UK and results may take up to one week to be reported. Indications may include
elucidation in a patient complaining of rhinorrhoea for example. Thus it is not useful in the clinical
scenario described above given the delays in reporting.
- You review a 28- year- old woman two days post normal vaginal delivery.
She received epidural analgesia in labour. She complains of severe postural headache and double vision. On examination she in unable to abduct her left eye. The most likely cause of her symptoms is:
A. Cerebral venous thrombosis
B. Subdural haemorrhage
C. Migraine
D. Multiple sclerosis
E. Dural puncture headache
- E
The patient has a sixth nerve (abducens) palsy causing failure of lateral eye movement causing
diplopia.
This is the most common cranial nerve palsy after dural puncture associated with intracranial
hypotension. The patient also complains of postural headache and had an epidural in labour.
No further information is offered regarding complications during insertion of the epidural.
However, this does not exclude a subsequent headache and in fact is a not an infrequent finding.
The other causes are rare; however, a pragmatic lower threshold for imaging prior to considering
epidural blood patch is recommended due to the presence of new coexisting neurology.
3. The most common cause of pregnancy- related death worldwide is: A. Sepsis B. Suicide C. Haemorrhage D. Embolism E. Hypertensive disorders
- C
About 830 women die from pregnancy or childbirth- related complications around the world
every day. It was estimated that in 205, approximately 303,000 women died during and following
pregnancy and childbirth. Almost all of these deaths occurred in low- resource settings, and
most could have been prevented. According to the WHO, haemorrhage accounted for 27.%,
hypertensive disorders 4.0%, and sepsis 0.7% of maternal deaths. The remainder of deaths
were due to abortion 7.9%, embolism 3.2%, and all other direct causes of death 9.6%. Regional
estimates vary substantially. Haemorrhage is the sixth most common direct cause of maternal death
in the UK.
- A Jehovah’s witness is receiving a transfusion of 200 mL of salvaged blood following an uneventful elective caesarean section.
Blood loss during surgery was 400 mL. She suddenly reports feeling unwell.
Heart rate is 120 bpm and BP 60/ 30. The most likely complication of transfusion is:
A. ABO incompatibility B. Transfusion via leucodepletion filter C. Amniotic fluid contamination D. Sepsis E. Contamination with fetal red cells
- B
Leukodepletion filters are recommended in obstetrics by AAGBI guidance. There have been recent
reports of severe hypotension with re- infusion of salvaged blood using leukocyte depletion filters.
The mechanism is likely to be bradykinin release and management includes stopping transfusion,
removing the filter, and transfusing without the filter. ABO incompatibility is unlikely as the patient
is receiving their own blood back and being a Jehovah’s witness the extracorporeal circuit would be
set up in continuous connection with the patient. Salvaged blood would be unlikely to have become
contaminated to cause sepsis during an uncomplicated caesarean and the time frame is one of
immediate re- transfusion.
Amniotic fluid is reduced by washing and a two- suction set up. Fetal red cell contamination is
reduced by filtration with maternal sensitization for subsequent pregnancies a greater concern.
- Regarding inadvertent dural puncture during labour epidural administration, which of the following has the largest impact on reducing the appearance of headache?
A. Higher gauge Tuohy needle B. Restriction of pushing C. Intrathecal saline administration D. Prophylactic epidural blood patch E. Supra- normal fluid intake
- A
There is substantial evidence that using a smaller epidural needle (higher gauge, e.g. 8G instead of
6G) reduces the risk and severity of headache. There is a lack of sufficient evidence in support of
the other options in the questions.
- You are asked to review a 22- year- old woman in early labour. She has a history of hydrocephalus from childhood and a functioning ventriculoperitoneal
shunt in situ. She has no neurological symptoms. The most correct advice is:
A. Epidural analgesia or spinal anaesthesia can be offered as needed
B. Epidural analgesia can be offered but spinal anaesthesia should be avoided
C. Epidural analgesia should be avoided but spinal anaesthesia can be offered
D. Neuraxial techniques are absolutely contraindicated
E. Discuss caesarean section at the earliest opportunity under general anaesthetic
- A
If the shunt is functioning normally as suggested by an absence of symptoms of hydrocephalus, then both neuraxial techniques have been used and can be offered.
Vaginal delivery is the preferred route in women with a functioning shunt. However, neuraxial techniques in women with shunt failure are generally considered to be contraindicated and could increase the risk of brain
herniation.
Caesarean section is indicated with shunt failure and raised ICP.
Caesarean delivery may also potentially damage the peritoneal part of the shunt.
- A 28- year- old primigravida requires lumbar epidural analgesia in labour.
During insertion of the epidural a recognized dural puncture occurs with an 18G Tuohy needle.
The best way of reducing the incidence of
headache now is:
A. Injection of intrathecal saline
B. Insertion of intrathecal catheter and leave in place for 24 hours
C. Establish epidural analgesia
D. Intrathecal opioid administration
E. Prophylactic epidural blood patch
- B
Various strategies to prevent the onset of headache have been used such as prophylactic epidural
blood patch (EBP) or intrathecal saline injection.
The most widely practiced is that of inserting an
intrathecal catheter at the time of dural puncture. Study results are conflicting but suggest that most
benefit occurs when the catheter is left in place for 24 hours. A recent meta- analysis demonstrated
a significant reduction in the incidence of post dural puncture headache (PDPH) from 66% to 51%
and requirement for EBP from 59% to 33% after intrathecal catheter placement.
However, the monitoring and procedures in place to ensure safety of this practice in an individual
unit is of paramount importance and should also be considered.
8. The most common cause of major obstetric haemorrhage is: A. Uterine rupture B. Uterine atony C. Placental abruption D. Placenta praevia E. Placenta accreta
- B
Although blood loss may be concealed or difficult to measure, fetal distress, loss of uterine tone, and rising abdominal girth may indicate ongoing blood loss. The majority of bleeds are post- partum and caused by uterine atony. Many of the other causes of haemorrhage are also a risk factor for uterine atony.
- A 45- year- old para 4 patient has just delivered a 4.0 kg baby by forceps in theatre. Her epidural has been topped up to provide analgesia. She is
having a post- partum haemorrhage. The blood loss is currently 1 L and is ongoing. So far, you have given oxytocin 5 units IV, a further 5 units of oxytocin IV, ergometrine 500 μg IV, one dose of carboprost 250 μg IM.
An oxytocin infusion has been commenced. The next best step in the pharmacological management of haemorrhage is:
A. Give vitamin K 10 mg IV
B. Give oral misoprostol 600 μg
C. Give tranexamic acid 1 g IV
D. Give recombinant factor VIIa
E. Give calcium carbonate 10 mmol/ L IV
- C
The post- partum haemorrhage is most likely due to uterine atony as she is multiparous and has
delivered a large baby. In addition, there may be trauma to the birth canal following delivery.
T
ranexamic acid has been shown to be beneficial in the management of post- partum haemorrhage.
Although it is not yet clear if this finding will be transferable to a UK cohort it remains the best
answer as all others can be excluded as being less useful.
To be of benefit, it must be given as soon as possible after the haemorrhage is diagnosed: 1 g is
given initially with a further 1 g given 30 min later.
Oral or PR misoprostol can be given in the absence of intravenous access or if there are no
supplies of the IV drug preparations.
Recombinant factor VIIa is used in the prevention and treatment of bleeding due to haemophilia.
Vitamin K is indicated to reverse warfarin therapy Calcium replacement may be required during
subsequent blood transfusion.
10. You are asked to review a mother two days post partum complaining of unilateral leg weakness when crossing her legs. She had an epidural sited during first stage of labour before delivery of a 3.3kg baby by mid- cavity forceps. What is the most likely cause of her postpartum neurological deficit? A. Lithotomy position for delivery B. Epidural injury C. Forceps delivery D. Stroke E. Descent of fetal head
C0. C
She has an obturator nerve palsy. Obstetric causes most likely. The classic feature is weakness
of leg adduction (difficulty crossing legs) with a patch of numbness on the inner aspect of thigh if
examined. Women presenting with neurological dysfunction in the post- partum period may have
symptoms secondary to either complications of regional anaesthesia or obstetric nerve injury. The
overall incidence of major complications resulting in permanent harm following central neuraxial
blockade (spinal and/ or epidural block) in the obstetric population is in 80,000 to in 320,000.
Clinically important transient neurological dysfunction from an obstetric cause is estimated to be
in 500, i.e. much more common.
Lithotomy position can lead to foot drop due to compression of common peroneal nerve by the
stirrups. Stroke is rare and likely to produce a central nerve lesion deficit, e.g. hemiparesis.
A common cause of problems is the fetal head compressing the lumbosacral trunk where it crosses
the posterior pelvic brim before descending in front of the sacral ala. Usually, however, this causes
femoral nerve symptoms with limited quadriceps strength and also reduced hip flexion. Foot drop
can be a notable consequence of these mechanics too. The foot drop is almost always unilateral
and on the opposite side to the fetal occiput resulting in weak dorsiflexion and eversion with
decreased sensation on the lateral lower leg and dorsal foot.
- A 24- year- old primigravida is having a category 4 caesarean section for placenta praevia. She is rhesus negative; 600 mL of blood has been salvaged. What is the most appropriate management regarding infusion
of salvaged blood?
A. No leukodepletion filter, perform re- crossmatch post transfusion
B. Use leukodepletion filter, perform Kleihauer test post transfusion
C. Use leukodepletion filter, perform re- crossmatch post transfusion
D. Use leukodepletion filter, perform Coomb’s test post transfusion
E. No leukodepletion filter, perform Kleihauer test post transfusion
11 B
Concerns about amniotic fluid embolism, rhesus sensitization, and fetal debris contamination
previously limited the use of cell salvage in obstetric practice. However, to date, there have
been no proven cases of amniotic fluid embolism caused by reinfusion of salvaged blood in
the literature. The utilization of leucodepletion filters during transfusion of salvaged blood
can reduce the fetal squamous cell contamination to a level comparable with maternal blood
contamination.
However, it is not recommended that salvaged blood be pressurized through
these filters as it may cause hypotension from the release of vasoactive substances such as
bradykinin.
The cell saver cannot distinguish fetal from maternal red cells. If the mother is rhesus negative (and
the fetus RhD positive) the extent of maternal exposure should be determined by Kleihauer testing
as soon as possible and a suitable dose of anti- D immunoglobulin given (usually 25 IU/ mL of fetal
blood).
- A primigravida with severe pre- eclampsia on labour ward is 4 cm dilated and requesting an epidural.
On admission earlier today her blood pressure was 160/ 110 mmHg and is currently 40/ 90 mmHg after oral labetolol.
She has significant proteinuria. Her platelet count at her midwife appointment two days ago was 206 × 109/ L and on admission earlier today was 141 × 09/ L with normal coagulation. What is the best
advice for her labour analgesia?
A. Proceed with epidural
B. Commence Entonox N2O/ O2. Review need for epidural subsequently
C. Commence 5 mg of IM diamorphine intermittently as required
D. Commence remifentanil PCA
E. Commence morphine patient controlled
2. A
An epidural technique will help control blood pressure and improve placental blood flow. It will also
allow conversion to epidural anaesthesia if assisted or operative delivery required.
This is superior to IM opioid and preferable to remifentanil in this case. PCA morphine is not suitable for labour pain due to its kinetics and Entonox will provide only low grade analgesia leaving blood pressure susceptible to surges with contraction pain. Her platelet count has had a modest fall over a period of days which is not obviously precipitous. It is still at a level where epidural can be reasonably considered.
3. You are treating a 26- year- old primigravida who is at 37 weeks’ gestation. She has severe pre- eclampsia and is receiving both intravenous magnesium sulphate infusion and labetalol infusion. She now complains of double vision. On examination you note she has a
respiratory rate of 12 bpm, BP of 50/ 90, O2 saturations of 95% on air, and has lost her patellar reflexes. What would be the next step in the
pharmacological management of this patient?
A. Bolus of labetalol
B. Bolus of hydralazine
C. Bolus of lorazepam
D. Bolus of magnesium sulphate
E. Bolus of calcium gluconate 0%
E3. E
This patient is exhibiting signs of hypermagnesaemia and the management would be to stop
magnesium infusion and give calcium.
The other options are treatments for pre- eclampsia/ eclampsia.
- A 25- year old primigravida presents for antenatal anaesthetic assessment at 32 weeks’ gestation. She has a history of benign intracranial hypertension which has been asymptomatic.
She is otherwise well and has a normal BMI. She is keen for a normal vaginal delivery and wants to discuss her options. You recommend:
A. Treat as normal
B. Allow labour but avoid all neuraxial blocks for labour and delivery
C. Early labour epidural
D. Elective caesarean section under spinal
E. Elective caesarean section under general anaesthetic
4. C
Benign intracranial hypertension is a diagnosis of exclusion described as raised intracranial pressure
(ICP) in the absence of an intracranial lesion, hydrocephalus or infection, and normal cerebrospinal
fluid (CSF) composition.
Patients usually present with headache characteristic of raised ICP, visual disturbance, and nausea. The condition is more common in obese women while symptoms often worsen during pregnancy and improve after delivery.
Symptomatic patients are at risk of further
compromise if allowed to labour due to an increase in CSF and epidural pressures during uterine
contractions and the second stage of labour.
Asymptomatic patients should be offered effective
regional analgesia and an elective instrumental will reduce surges in ICP.
- You review a 31- year- old para 1+0 patient in recovery after an isolated
BP reading of 75/ 40 mmHg. She had a category 2 caesarean section under spinal anaesthesia with intrathecal diamorphine, 4 hours earlier, during which she lost 1,500 mL of blood. She complains of mild
abdominal discomfort on moving and right shoulder tip pain. Heart rate is 102, respiratory rate 22, and capillary refill time 3 seconds. She is apyrexial and has passed 20 mL of urine postoperatively. What is the
most likely cause of her symptoms?
A. Sepsis
B. Pulmonary embolism
C. Overdose opioid
D. Hypovolaemia
E. Blocked catheter
- D
This is a common clinical picture in recovery in obstetrics and ongoing bleeding must be suspected.
Blood pressure is well maintained in otherwise fit adults until compensation is no longer possible. At this stage 30– 40% of circulating blood volume has been lost. Any episode of hypotension should be
taken seriously.
The patient’s signs are consistent with hypovolaemia. (tachycardia, hypotension, increased
respiratory rate, and prolonged capillary refill time). A full blood count will help differentiate
between a lack of fluid intake and occult intra- abdominal bleeding. Sepsis should be considered post
caesarean section but would usually be accompanied by pyrexia or hypothermia. Full blood count
will provide estimation of neutrophil count. Her low urine output is worrying and serum urea and
electrolytes should be checked and the catheter flushed to exclude obstruction. However, catheter
obstruction and bladder distension would cause a raised blood pressure and constant discomfort.
Her respiratory rate is raised making opioid overdose unlikely.
