Obstetric Emergencies

Question 1

What is Shoulder Dystocia?

Answer 1

-Impaction of the fetal shoulders at the maternal pelvis, occurring after the birth of the head.
-It is defined by the need for additional obstetric manoeuvres to assist the birth of the infant, when routine axial traction has failed to deliver the anterior shoulder.
=Routine axial traction is used to deliver an infant without SD.
-Most commonly, SD is caused by the anterior shoulder impacting behind the maternal symphysis pubis. However, it may also be caused by the posterior shoulder impacting on the sacral promontory.
-The incidence is in the range of 0.1% to 3% of vaginal births and is increasing.

Question 2

Risk factors for shoulder dystocia

Answer 2

-Antepartum
=Previous shoulder dystocia (increases incidence to 12-17%)
=Macrosomia
=Maternal diabetes mellitus
=Advanced gestational age
=Maternal obesity

-Intrapartum
=Prolonged first stage
=Prolonged second stage
=Augmentation of labour
=Instrumental birth (forceps or vacuum)

HOWEVER: 50% of SD occurs in normal-sized fetuses and 98% of large babies do not have SD

Question 3

Prevention of shoulder dystocia

Answer 3

-All women with a previous SD should receive counselling about their birth options in the antenatal period, with discussion between caesarean or vaginal birth with the relevant risks and benefits; a Cochrane decision tool is available to guide the discussion.
-Induction of labour between 37 and 39 weeks for babies with an estimated fetal weight of >4 kg at term has been demonstrated to reduce the risk of SD by 40%, but with no improvement in clinical outcomes and a three-fold increase in severe perineal injury

Question 4

Presentation of SD

Answer 4

-Slow or difficult birth of the face and chin
-Tight retraction of the head against the vulva
-Chin retraction (‘turtle-neck sign’)
-Lack of restitution of the fetal head.
-However, a diagnosis cannot be made until there is failure of delivery of the anterior shoulder with routine axial traction.

Question 5

Management of SD

Answer 5

-Discourage pushing (increases impaction), lie flat and move mother’s buttocks to edge of mattress if on a bed, after every manoeuvre diagnostic axial traction

-McRoberts position (thighs to abdomen to optimise diameter of pelvic inlet, consider all fours if lone birth attendant)
-Suprapubic pressure (reduces fetal shoulder-to-shoulder diameter, CPR position of hands)

-Internal manoeuvres:
=Delivery of the posterior arm (reduce diameter of shoulders, if forearm felt)
=Internal rotation manoeuvres
=Both insert hand posterior to sacral hollow

-Consider cleidotomy, Zavanelli manoeuvre (replacing fetal head in uterus and birth by caesarean) or symphysiotomy (division of symphysial joint with scalpel to increase pelvic diameter) as last resort

Question 6

Complications of SD

Answer 6

-Occluded umbilical cord (between the fetal trunk and the maternal pelvis)
=rapid fetal hypoxia that may lead to brain injury and death.
=Low rates of hypoxic ischaemic encephalopathy when the head-to-body interval is less than 5 minutes.
=neonatal fluid resuscitation may be useful for infants who are difficult to resuscitate post-SD, probably due to hypovolaemia post–cord occlusion.

-Excessive traction, downward traction, and rapid application of force (jerking) are all associated with neonatal injury, particularly permanent injury to the anterior brachial plexus.
=Brachial plexus injury occurs in 2.3% to 16.0% of SD cases
=Most are temporary, but 10% of will be permanent (>12 months), leading to life-long disability of the upper limb.
-Neonatal fractures of the humerus and clavicle may also occur
-Maternal complications, such as genital tract trauma and postpartum haemorrhage

Question 7

What is eclampsia?

Answer 7

-Complication of severe PET (1%)
-Characterised by convulsions that cannot be attributed to a primary neurological problem (e.g., epilepsy, cerebral infarction, tumour cerebral infection, or ruptured aneurysm).
-44% of eclamptic seizures occur in the postpartum period.
-Neurological complications include focal motor deficits, coma, cortical blindness and cerebral haemorrhage.

Question 8

Epidemiology of eclampsia

Answer 8

-Global prevalence: 0.6%.
-UK incidence: steadily declining, with a reduction of over 90% observed since the 1920s, related to improved detection and management of hypertensive pregnancies.
-Risks of serious adverse maternal and perinatal outcomes are high among women with eclampsia.
=In areas with low maternal mortality, the case-fatality rate is below 1%, but severe maternal complications (such as coma, stroke and acute respiratory distress) occur in 10% to 30% of cases, with 5% to 8% of pregnancies resulting in a perinatal loss.

Question 9

Risk factors for eclampsia

Answer 9

Pre-eclampsia

Question 10

Presentation of eclampsia

Answer 10

-Tonic-clinic seizures not attributable to other causes (40% post-partum)

Question 11

Management of eclampsia

Answer 11

-Woman should be turned onto her left side to avoid aortocaval compression.
-The airway should be secured and high-flow oxygen should be administered.
-Magnesium sulphate (MgSO 4 4g over 5-10 minutes ) should be administered intravenously to terminate the seizure and then by intravenous (IV 1g/hour) infusion to reduce the chance of further convulsions.
=In settings where IV infusion pumps are not available, MgSO 4 can be administered intramuscularly (IM) to reduce the risk of over- or under-dosing.
=The infusion should be continued for at least 24 hours following delivery or after the last seizure.
=MgSO 4 can depress neuromuscular transmission and the woman should be monitored for signs of toxicity. The respiratory rate and patellar reflexes should be monitored (reduced patellar reflexes usually precede respiratory depression) as well as UO abd oxygen saturations
-If there is significant respiratory depression, calcium gluconate can be used to reverse the effects of MgSO 4 and consideration given to ventilation.
-Urgent delivery is necessary if the seizure has occurred antenatally or intrapartum.
-Paralysis and ventilation should be considered if the seizures are prolonged or recurrent
-Fluid restriction to avoid fluid overload

Question 12

Types of haemorrhage definitions

Answer 12

-Threatened miscarriage – up to 24 weeks’ gestation
-Antepartum haemorrhage (APH) – from 24 weeks’ gestation until the onset of labour
-Intrapartum haemorrhage – from the onset of labour until the end of the second stage
-Postpartum haemorrhage (PPH) – from the third stage of labour until 12 weeks after delivery

Question 13

Classifications of antepartum haemorrhage

Answer 13

-Minor APH is <50 mL and stopped
-Major APH is 50 to 1000 mL and no hypovolaemic shock
-Massive APH is >1000 mL and/or hypovolaemic shock

Question 14

Causes of antepartum haemorrhage

Answer 14

-Local
-Placenta praevia
-Placental abruption
-Unexplained (50%)

Question 15

Describe local causes of antepartum haemorrhage

Answer 15

-Bleeding from the woman’s vulva, vagina or cervix.
-Bleeding from the cervix is not uncommon in pregnancy and may follow sexual intercourse (post-coital bleeding).
=A cervical ectropion or benign polyp is often found; rarely, a diagnosis of cervical carcinoma is made.
=The passing of a blood-stained ‘show’, mucus along with a small amount of blood, may herald the onset of labour as the cervix becomes effaced.

Question 16

What is placenta praevia?

Answer 16

-Low lying placenta when the placental edge is less than 2 cm from the internal os and placenta praevia when the placenta lies directly over and covers the internal os.
=Transvaginal ultrasound scanning
=Wholly or partly in lower uterine segment

Question 17

Classifications and presentation of placenta praevia

Answer 17

-Minor
=I: Encroaches the lower uterine segment
=II: Reaches internal os of the cervix (marginal)
-Major
=III: Covers part of internal os (partial)
=IV: Completely covers the internal os (complete)
-Anterior, posterior or lateral

-Uterus is usually soft, the presenting part will usually be free and the fetal heartbeat is usually present

Question 18

Management of placenta praevia

Answer 18

-Women with pregnancies in which the placenta is low lying (less than 2 cm from the internal os) or praevia are recommended to give birth by caesarean section.
-Placental location is routinely determined at the time of the fetal anatomy scan at 18 to 22 weeks and may be found to be low lying or praevia at that stage
-As the uterus grows from the lower segment upwards, the placenta appears to move upwards with advancing gestation, with resolution of low-lying placenta in 90% of cases before term. This is not a reflection of placental migration; rather, it is simply a feature of uterine growth. When a low-lying placenta is detected on ultrasound scanning early in pregnancy, it is necessary to repeat the scan early in the third trimester and then review the woman’s care if placenta praevia persists

Question 19

Risks of placenta praevia

Answer 19

-Sudden, unpredictable, major or massive haemorrhage.
=The woman’s care may be either as an inpatient or outpatient.
=Factors that will affect this decision include distance and transport availability to a hospital where facilities for resuscitation and birth are immediately available, number of episodes of bleeding and their severity, haematology results, and willingness to accept blood and/or blood products.
=Elective birth by caesarean section is usually planned for 36 to 37 weeks but will be considered earlier if there is a history of vaginal bleeding or other risk factors for pre-term birth.

Question 20

What is placental abruption?

Answer 20

-Retroplacental haemorrhage (bleeding between the placenta and the uterus) as a result of some degree of placental separation prior to birth of the baby.
-Separation of the placenta results in a reduced area for gas exchange between the fetal and maternal circulations, predisposing to fetal hypoxia and acidosis.
-It is crucial to remember that with placental abruption the amount of ‘revealed’ blood (bleeding from the vagina) may not reflect the total blood loss and that a woman may have considerable retroplacental bleeding without any external loss at all – a ‘concealed abruption’

Question 21

Risk factors for placental abruption

Answer 21

-Previous placental abruption
-Pre-eclampsia
-Fetal growth restriction
-Non-vertex presentations
-Polyhydramnios
-Advanced maternal age
-Multiparity
-Low body mass index
-Pregnancy following assisted reproductive techniques
-Intrauterine infection
-Premature rupture of membranes
-Abdominal trauma
-Smoking
-Drug misuse (cocaine and amphetamines)

Question 22

Investigations of placental abruption

Answer 22

-Ultrasound?

Question 23

Presentation of placental abruption

Answer 23

A major concealed abruption is inferred from the degree of pain, uterine tenderness and evidence of hypovolaemic shock; again, urgent birth may be required
-uterus is typically hard and tender (‘Couvelaire’ uterus) and the fetal heartbeat may be absent. There may be frequent contractions or continuous pain
-The woman usually describes pain and frequent contractions, the contractions precipitated by irritation of the myometrium from the retroplacental clot. The fetal heart rate will often show a suspicious or pathological pattern, which may progress to a fetal bradycardia and fetal death unless birth of the baby is expedited= placental separation with fetal compromise

Question 24

Management of placental abruption

Answer 24

-Urgent birth when major revealed haemorrhage
-The decision between vaginal and caesarean birth is influenced by the degree of bleeding coupled with maternal and fetal conditions
-If intrauterine fetal death is diagnosed, vaginal birth is to be preferred, if safe to do so, although the woman’s preferences should always be considered.
=major degree of blood loss= hypovolaemic shock may develop and may progress to multisystem organ failure if not corrected. In addition, release of thromboplastins from the damaged placenta may lead to disseminated intravascular coagulation (DIC) with depletion of platelets, fibrinogen and other clotting factors. Therefore, waiting for the baby to be born vaginally carries risks, and caesarean birth may occasionally be indicated to minimise these systemic maternal risks. Deciding on the appropriate mode of birth is further complicated by the risks of carrying out an operation in the presence of DIC

Question 25

Investigation and management of minor haemorrhage with a soft uterus and normal cardiotocography

Answer 25

-USS scan: determine the placental site (if not already established by an earlier scan)
-Provided that the placenta is not praevia, a speculum examination should be performed to look for cervical effacement or dilatation, an ectropion or a cervical polyp.
=If all is normal, it is common practice to admit the woman at least until the bleeding stops.
= However, most clinicians will not admit the woman if the bleeding is minor and clearly seen to be coming from an ectropion.
=Women whose blood group is rhesus negative are advised to receive prophylactic anti-D.

-If there is a placenta praevia and the pregnancy is at more than 36 to 37 weeks’ gestation, it is reasonable to arrange for birth by caesarean section. If less than this gestation, a conservative approach may be appropriate if the bleeding has settled.

Question 26

Investigation and management of minor/major haemorrhage with hard, tender uterus

Answer 26

-Probably a placental abruption (concealed and revealed).
=Clinical care revolves around maternal resuscitation, correction of hypovolaemia and coagulation defects and evaluation of the fetal condition by cardiotocography.
=Expediting birth is highly likely to be appropriate; the route of birth will be influenced by a number of factors, including evidence of fetal compromise and the presence or absence of maternal coagulopathy

Question 27

Causes of intrapartum haemorrhage

Answer 27

-Placental abruption (if uterus does not relax between contractions)
-Placenta praevia (painless bleeding with placenta separates from uterine wall when cervix dilates)
-Uterine rupture (rare)
-Vasa praevia

Question 28

What is vasa praevia?

Answer 28

-1 in 1200 and 1 in 5000
-Umbilical cord vessels run in the fetal membranes and cross the internal os of the cervix= rupture spontaneously in early labour or may be ruptured at the time of amniotomy, which may lead to fetal exsanguination.
-It may be that the cord is inserted into the membranes rather than directly into the placenta (type 1 vasa praevia)
-or that the vessels are running from the placenta to a separate succenturiate (accessory) placental lobe (type 2 vasa praevia).

Question 29

Presentation and diagnosis of vasa praevia

Answer 29

-Pathological cardiotocography (CTG) or fetal death following a minor intrapartum haemorrhage.
-In the presence of an APH, diagnostic tests to differentiate fetal from maternal blood are seldom reliable and the baby is usually born urgently by caesarean section because of the fetal compromise.
-The diagnosis of vasa praevia is often only made retrospectively, by examination of the placenta and membranes.
-Although it is possible to diagnose the condition antenatally with colour flow Doppler ultrasound, routine screening for vasa praevia is not established practice, as there is concern there may be a high false-positive rate and no evidence of benefit is currently available.
-Risk factors for vasa praevia have been identified, with velamentous cord insertion and placenta praevia being the most common.

Question 30

Classification of postpartum haemorrhage

Answer 30

-There is inevitably some bleeding during the third stage of labour, usually around 200 to 300 mL following a vaginal birth.

=A primary PPH is defined as a blood loss of 500 mL or more within 24 hours of birth. The PPH is ‘minor’ if blood loss is 500 to 1000 mL with no hypovolaemic shock and ‘major’ if >1000 mL and continuing or associated with hypovolaemic shock.
=A secondary PPH is any excess vaginal blood loss between 24 hours and 12 weeks after the birth

Question 31

Epidemiology of primary PPH

Answer 31

-18% of all births.
-It is more common in women of high parity (four deliveries or more), women over 35 years of age, women with a body mass index of over 35, multiple pregnancy, women with fibroids, placenta praevia and in those who have had a long labour or an instrumental birth.
-It may also follow an APH and is more likely in women with a past history of primary PPH.
-Women with risk factors for PPH are advised to give birth in a consultant-led unit

Question 32

Pre-existing maternal risk factors for Primary PPH

Answer 32

-High parity
-Maternal age >35 years
-Anaemia
-Raised body mass index
-Uterine fibroids
-Coagulation disorders

Question 33

Pregnancy risk factors for primary PPH

Answer 33

-Multiple pregnancy
-Fetal macrosomia
-Polyhydramnios
-Previous postpartum haemorrhage
-Antepartum haemorrhage in current pregnancy
-Prolonged 2nd stage of labour
-Instrumental birth
-Retained placenta and placenta accreta
-Episiotomy and/or genital tract trauma
-General anaesthesia

Question 34

The 4 ‘T’ causes of primary PPH

Answer 34

-Tone
=Poor uterine contractility or atony.
=This is the most common cause of primary PPH (90%).
=Normally, contraction of the uterus in the third stage of labour causes compression of intramyometrial blood vessels, and bleeding from the placental site stops promptly. If there is uterine atony, this compression does not occur

-Trauma
=Bleeding may be from an episiotomy, a vaginal tear, cervical laceration or a rupture of the uterine wall.
=Lacerations of the genital tract are more common after an instrumental birth.

-Tissue
=Retained placental tissue inhibiting uterine contractility.
=Placental tissue is considered retained if the placenta is not delivered in 30 minutes with active management or 60 minutes with physiological management and affects 2% to 3% of all vaginal births.
=The physical presence of placental tissue prevents effective uterine contraction and the partial placental separation results in bleeding from the placental bed.
=More likely in the presence of an abnormally invasive placenta, which is termed ‘placenta accreta spectrum’
=The severity of this condition ranges from invasion deep into the myometrium down to the serosa (known as an ‘increta’) or even through the uterine wall, invading surrounding pelvic organs such as the bladder (known as ‘percreta’).
=Women with a placenta praevia overlying a previous caesarean section scar are at very high risk of this serious complication.

-Thrombin
=Coagulopathy, usually DIC. DIC can occur in association with a number of different causes, including maternal sepsis, placental abruption and PPH, in which the blood loss causes the DIC and the DIC exacerbates the blood loss.

Question 35

Risk factors for placental accreta spectrum

Answer 35

-Previous caesarean section
-Placenta praevia
-Advanced maternal age
-High parity
-Previous retained placenta
-History of dilatation and curettage or suction termination of pregnancy
-Previous postpartum endometritis

Question 36

Classification of abnormal placental attachment

Answer 36

-Placenta accreta (75%–78%)
=Invades superficially into the myometrium.

-Placenta increta (17%)
=Invades deep into the myometrium.

-Placenta percreta (5%–7%)
=Invades through the myometrium and penetrates the outer serosal layer of the uterus. It may invade adjacent structures, including bladder and bowel.

Question 37

Clinical presentation of primary PPH

Answer 37

-The bleeding is usually obvious.
-Occasionally, however, an atonic uterus can fill up without obvious external loss, and the first sign of the PPH is hypovolaemic shock.
-A less dramatic, prolonged trickling of blood may go unnoticed, the significance of which may not be initially appreciated.
-With blood-soaked pads and bedding, it is common to underestimate the loss.

The key questions are:

1 Has the placenta been delivered and is it complete?
2 Is the uterus firmly contracted?
3 If so, is the bleeding due to trauma?

Question 38

Investigation of primary PPH

Answer 38

-Measure the loss by weighing pads.
-Determine the pulse and blood pressure.
-Palpate the abdomen to assess the size and tone of the uterus.

Question 39

Treatment and interventions of primary PPH

Answer 39

-If the uterus is atonic, a contraction can be ‘rubbed up’ by abdominal massage. Bimanual compression may also be performed
-Intravenous (IV) access should be established with two wide-bore cannulae and blood taken for haemoglobin concentration, platelet count, blood clotting and a red cell cross-match (the number of units depends on volume lost).
-An IV bolus of oxytocin 5 IU should be given to further contract the uterus, followed by an oxytocin infusion (usually 40 IU in 500 mL isotonic crystalloids at 125 mL/h).
-The woman’s bladder should be emptied and an in-dwelling catheter left in situ to monitor the urinary output.
-Crystalloid and/or colloid up to 3.5 L should be rapidly infused to maintain the circulating volume. With rapid blood loss, O rhesus-negative blood may need to be given.
- Further oxytocics can be given, for example, further boluses of IV oxytocin, IM ergometrine, IM carboprost and/or rectal misoprostol (carboprost and misoprostol are synthetic prostaglandin analogues).
-The antifibrinolytic drug, tranexamic acid 1 g IV, has been shown to improve outcomes in women undergoing PPH.
-Bleeding from genital tract lacerations should be diagnosed promptly by examination (often under regional block or general anaesthesia) and bleeding arrested by application of clamps and suturing

Question 40

What if the placenta has not been delivered in primary PPH?

Answer 40

-Gentle attempt at umbilical cord traction should be tried.
-If still retained, a regional block or general anaesthetic will be required for a manual removal of the placenta (where a hand is passed into the uterus through the cervix to strip off the placenta under aseptic conditions) .
-The procedure must be covered with antibiotics, as there is a significant association between manual removal of the placenta and postpartum endometritis

Question 41

Additional management of haemorrhage continues despite initial intervention

Answer 41

-Arterial line and blood transfusion commenced.
-The coagulation defects of DIC should be corrected with fresh frozen plasma or cryoprecipitate following consultation with a haematologist.
-Maintaining compression of the uterus or applying pressure directly to the placental bed.

=A ‘brace’ suture involves an additional laparotomy (unless the haemorrhage is following a caesarean section) and the placing and tying of sutures around the uterine body in order to maintain compression. The most commonly known type of brace suture is called a ‘B-Lynch’ suture.
=Placement of an intrauterine balloon does not require a laparotomy and works by applying pressure directly to the placental bed. Balloon insertion is effective in the majority of cases in which it is considered appropriate.

-Hysterectomy may be indicated, especially if there is an abnormally invasive placenta. In acknowledgement of the high PPH risk, it is recommended that women with suspected placenta accreta should give birth by caesarean section in a specialist centre. Conservative management (when the placenta is left in situ to be absorbed over time) is an option with placenta accreta, though this is associated with a significant incidence of major complications from infection and bleeding, and the woman must be monitored closely for several weeks (sometimes months) following discharge.

=Internal iliac artery ligation is occasionally performed but requires a high degree of surgical skill. Radiologically directed arterial embolization is an option in the management of PPH, provided that the woman is stable for transfer to the radiology theatre suite. This procedure is highly specialised and is performed by interventional radiologists. Embolization often enables haemorrhage to be controlled without resorting to hysterectomy.

Question 42

What causes secondary PPH?

Answer 42

-This is usually caused by infection of the uterine cavity (endometritis), retained products of conception, or both.
-Exceptionally, it is due to trophoblastic disease.

Question 43

Investigation of secondary PPH

Answer 43

-Pulse rate, blood pressure and temperature
-Uterus palpated for tenderness.
-Endocervical and vaginal swabs are sent for culture
-An ultrasound scan is often helpful in ruling out retained tissue.

Question 44

Management of secondary PPH

Answer 44

-Conservative management with antibiotics or arranging for an evacuation of retained products under regional or general anaesthesia.
-In the first week, the evacuation can often be carried out digitally without the need to instrument the uterus.
-Clinical judgement is important, often giving broad-spectrum antibiotics in the first instance if the bleeding is not severe and arranging an evacuation if the bleeding does not settle.
-Care is required to avoid perforating the postpartum uterus.
-Many clinicians perform the evacuation with real-time ultrasound to ensure that the instrument remains within the uterine cavity.