Abnormal Lie, Multiple Pregnancy and Labour

Question 1

Abnormal Lie - Risks

Answer 1

Preterm labour, polyhydramnios, high parity women, multiple pregnancy and conditions that prevent engagement e.g. placental previa or pelvic abnormality.

Question 2

Transverse or Oblique Lie

Answer 2

• Occurs in 1 in 200 births.
• The risk is that an arm or umbilical cord may prolapse when the membranes rupture which untreated can lead to uterine rupture.

Question 3

Transverse/Oblique Lie - Management

Answer 3

• No action required pre 37 weeks unless in labour.
• After 37 weeks women are admitted in case of ROM and ultrasound performed to identify any underlying cause e.g. placenta previa.
• Lie normally stabilises before 41 weeks.
• If labour commences and lie is persistently abnormal a C section is performed.

Question 4

Breech Presentation

Answer 4

• Occurs in 3% of term and 25% of premature pregnancies.
• 70% are extended (knees) breech, 15% are flexed breech and 15% are footling breech (one or two feet present below the buttocks)

Question 5

Breech presentation - Management

Answer 5

• External Cephalic Version - attempted at 37 weeks and succesful in 50% - less likely to succeed in nulliparous women, Caucasians, when breech is engaged, when head not easily palpable or with high uterine tone.
• C Section - if ECV fails or is contraindicated.

Question 6

Multiple Pregnancy

Answer 6

• Twins occur in 1 in 80 pregnancies.
• Triplets occur in 1 in 1000 pregnancies.
• The incidence of twins is increasing in the UK due to subfertility treatment.

Question 7

Multiple Pregnancy - Maternal Complications

Answer 7

Gestation DM, pre-eclampsia and anaemia

Question 8

Multiple Pregnancy - Fetal Complications

Answer 8

• Congenital abnormalities, late miscarriage, preterm labour and IUGR.
• Twin-twin transfusion syndrome - occurs in monochorionic (same placenta) twins due to unequal blood distribution - 1 is the donor and gets anaemic and 1 is the recipient and gets overloaded.

Question 9

Multiple Pregnancy - Intrapartum Complications

Answer 9

• 1st twin - malpresentation in 20% and this is an indication for C section.
• 2nd twin - hypoxia, cord prolapse, tetanic uterine contraction, placental abruption or breech presentation.

Question 10

Mechanical Forces of Labour - The Powers

Answer 10

Once labour is established the uterus contracts for 45-60 seconds every 2-3 minutes. This causes effacement (pulling up) and dilation of the cervix.

Question 11

Mechanical Forces of Labour - The Passage

Answer 11

• Inlet of bony pelvis - transverse diameter is 13cm and AP diameter is 11cm.
• Outlet of bony pelvis - transvers diameter is 11cm and the AP diameter is 12.5cm.
• Head position can be described in relation to the ischial spines - 0 is in line with and +/-2cm.

Question 12

Mechanical Forces of Labour - The Passenger

Answer 12

• Attitude - degree of flexion of the head on the neck. Ideal is maximal flexion = vertex presentation (diameter is 9.5cm)
• Position - degress of rotation of the head - should be transverse at the pelvic inlet and longitudinal at the outlet so head must rotate 90 degrees. The occiput is anterior in most cases (95%).

Question 13

Diagnosis of Labour

Answer 13

• Prostaglandins reduce cervical resistance and cause oxytocin release from the posterior pituitary which stimulated contractions.
• Dilation and effacement is accompanied by a show or mucous plug from the cervix and rupture of membranes causing release of liquor.

Question 14

First Stage of Labour

Answer 14

• From diagnosis of labour until cervix is 10cm dilated - should take <16 hours.
• Latent stage - first 3cm occurs slowly.
• Active stage - nulliparous women dilate at 1cm per hour and multiparous at 2cm per hour.
• Slow progress - can be helped by amniotomy and if not successful IV oxytocin. A C section is often performed if not fully dilated by 16 hours.

Question 15

Second Stage of Labour

Answer 15

• From full dilation of the cervix to delivery.
• Passive stage - lasts until the head reaches the pelvic floor and women has desire to push. If descent is poor can try IV Oxytocin.
• Active stage - the mother is pushing and the fetus is delivered - takes on average 20 mins in multiparous and 40 mins in nulliparous women. If takes > 1 hour may need ventouse or forceps.

Question 16

Third Stage of Labour

Answer 16

• From delivery of the fetus to delivery of the placenta - usually takes approx 15 minutes.
• Uterine muscles compress vessels but normal blood loss is around 500mls.

Question 17

Perineal Trauma

Answer 17

• The perineum remains intact in 50% multiparous and a third of nulliparous women.
• 1st degree - minor damage to fourchette (skin).
• 2nd degree tear and episiotomies - involves perineal muscle but not the anal sphincter.
• 3rd degree tear - involves the anal sphincter and occurs in just 1% of deliveries.
• 4th degree tear - involves the anal mucosa.

Question 18

Epidural Analgesia

Answer 18

• An injection of LA and opoid into the epidural space between L3 and L4.
• Sensory (except pressure) and partial motor blockade from the upper abdomen is the norm.
• The main complication is hypotension.

Question 19

Epidural - Advantages and Disadvantages

Answer 19

• Advantages - makes labour pain free (advised in long labour), reduce BP if high and prevents premature urge to push.
• Disadvantages - increasing monitoring of vital signs required, women are bed bound, can cause urinary retention, maternal fever is common and can cause spinal tap (accidental puncture of the dura mater causes CSF leak and headaches).

Question 20

Induction of Labour

Answer 20

• Prostaglandins - 2mg PGE2 gel placed in the posterior fornix, can be repeated 6 hours later. Starts labour or makes cervix more favourable.
• Cervical sweeping - finger through cervix and stripping between membranes and uterus.
• Amniotomy - amnihook to rupture membranes.
• Oxytocin - infusion can be started if labour hasn’t started within 2 hours of amniotomy.

Question 21

Induction of Labour - Complications

Answer 21

Labour may fail to start due to unefficient uterine activity, risk of C section or instrumental increased, uterus can be hyperstimulated causing fetal distress and risk of infection and PPH is higher.

Question 22

Prelabour Term Rupture of Membranes

Answer 22

• Small risk of neonatal infection - increased by VE, group B strep positive and duration until labour.
• Mx - monitor fetus with CTG, labour occurs in 80% within 24 hours, monitor maternal obs every 4 hours, if meconium or evidence of infection induce labour immediately. After 24 hours prescribe abx for GBS and induce labour.

Question 23

Instrumental Delivery

Answer 23

• 20% of nulli and 2% of multiparous women.
• Ventous (vacuum extractor) or forceps can be used to add power and if required rotation.
• Prerequisites - head must be at or below the ischial spines, cervix must be fully dilated, the position of the head must be known, must be adequate analgesia and bladder must be empty.

Question 24

Instrumental Delivery - Complications

Answer 24

• Maternal complications - increased risk of vagina laceration, blood loss and 3rd degree tears.
• Fetal complications - chignon (swelling due to cup of ventouse), facial bruising, nerve damage, skull or neck fractures can happen with forceps.

Question 25

Caesarean Section

Answer 25

• Occurs in 20-30% of births in developed world.
• The usual operation is a lower segment operation where the uterus is incised transversally to deliver the baby.
• Can occasionally be classic caesarean where the uterus is incised vertically e.g. in extreme prematurity, multiple fibroids or where the fetus is transverse.

Question 26

Caesarean Section - Complications

Answer 26

• Maternal - haemorrhage, increased need for blood transfusion, infection of the wound or uterus, visceral damage (bowel or bladder), postoperative pain, immobility and VTE.
• Fetal - increased risk of respiratory morbidity and bonding and breastfeeding are affected.

Question 27

Shoulder Dystocia

Answer 27

• Shoulders fail to deliver in 1 in 200 births - a delay of just 5 minutes can be fatal.
• Brachial plexus damage can occur (Erb’s or waiters tip palsy) and is permanant in 50%.
• Mx - gentle downward traction, McRoberts position (legs hyperestended) and suprapubic pressure or internal maneovres with episiotomy.

Question 28

Cord Prolapse

Answer 28

• After ROM the cord descends before the presenting part in 1 in 500 deliveries.
• If untreated the cord is compressed or goes into spasm leading to fetal hypoxia.
• Mx - prevent presenting part from compressing the cord, keep the cord warm and moist but don’t push it back inside, give tocolytics to prevent contractions and C section is normally performed.

Question 29

Amniotic Fluid Embolism

Answer 29

• A rare complication - only occurs in 1 in 50,000 births but causes 80% maternal deaths.
• When membranes rupture liquor enters maternal circulation and causes dyspnoea, hypoxia, hypotension. Can lead to seizures and arrest.
• Risks - polyhydramnois and strong contractions.

Question 30

Uterine Rupture

Answer 30

• Occurs in 1 in 1500 and mortality is 10%.
• The uterus tears, the fetus is extruded, the uterus contracts and bleeds from the rupture site causing fetal hypoxia and maternal haemorrhage.
• Mx - maternal resuscitation with IV fluids and blood, urgent laparotomy for delivery of the fetus and cessation of maternal bleeding by repair or removal of the uterus.