Abnormal presentation/ lie

Question 1

What is abnormal lie?

Answer 1

Any non-cephalic presentation

Question 2

Terms used to describe foetal positioning

Answer 2

Lie = relationship between the long axis of the foetus and the mother

Presentation = part of the foetus that first enters the maternal pelvis

Position = position of the foetal head as it exits the birth canal

Question 3

Most common foetal presentation

Answer 3

Cephalic vertex

Question 4

Most common position of foetal head as it exits birth canal

Answer 4

Occiput-anterior

The left occiput anterior (LOA) position is the most common in labor. In this position, the baby’s head is slightly off center in the pelvis with the back of the head toward the mother’s left thigh. The right occiput anterior (ROA) presentation is also common in labor

Question 5

What is the most common malpresentation?

Answer 5

Breech

Affects 3-4% foetuses at term

Question 6

Factors causing malpresentation

Answer 6

Maternal

• Pelvic tumours/ fibroids
• Congenital uterine anomalies
• Oligohydramnios
• Placenta praevia

Foetal

• Prematurity
• Anomalies e.g. hydrocephalus
• Multiple pregnancy
• Intrauterine death

Question 7

Clinical features of malpresentation

Answer 7

Suspected clinically on abdo palpation and confirmed by USS

Question 8

Discuss abnormal lie

Answer 8

Transverse and oblique lie occur in 1:300 pregnancies and resut in shoulder, limb and cord presentation

Vaginal delivery not possible unless abnormal lie corrected

Question 9

Diagnosis of abnormal lie

Answer 9

Mothers abdomen may appear wide

Fundus lower than expected for dates

Neither foetal pole is palpable entering pelvis

Foetal head palpable on one side

Pelvis empty on vaginal exam

Limb/ cord may prolapse through cervix

Question 10

Management of abnormal lie

Answer 10

External cephalic version @36-38 weeks depending on contraindications - if successful, exclude cord prolapse before allowing labour to progress

C-section is indicated in almost all cases

Question 11

Contraindications to external cepahlic version

Answer 11

Antepartum haemorrhage within last 7 days

Ruptured membranes

Uterine anomalies

Previous c-section

Multiple pregnancy

Abnormal CTG

Question 12

Outline abnormal presentations in labour

Answer 12

Any presentation other than vertex:

• Breech
• Brow
• Face
• Shoulder
• Arm
• Cord

Question 13

Frequency of brow presentation

Answer 13

1/1000 - 1/3500 deliveries

Can revert to face or vertex but if it persists normal delivery is not possible

Management: watch and wait, may become face or vertex presentation, if persists c-section needed

Question 14

How many births does face presentation occur in?

Answer 14

1:600 - 1:1500

Management: 90% are mentoanterior meaning the chin is anterior - normal labour can occur as head can flex

10% = mentoposterior and babies cannot be delivered in this presentation as would require hyperextension of the neck

Poor progress and failure to roate means c-section needed

Question 15

In which presentation is ventous absolutely contraindicated?

Answer 15

Face presentation

Can lead to opthalmic haemorrhages

Question 16

Discuss cord presentation

Answer 16

When one or more loops of the cord lie below the presenting part and membranes are still intact

Associated with malpresentation, abnormal lie and high head

Risk of cord prolapse when membranes rupture >> this is an obstetric emergency

Occult (incomplete) cord prolapse – the umbilical cord descends alongside the presenting part, but not beyond it.

Overt (complete) cord prolapse – the umbilical cord descends past the presenting part and is lower than the presenting part in the pelvis.

Cord presentation – the presence of the umbilical cord between the presenting part and the cervix. This can occur with or without intact membranes.

Question 17

Management of cord presentation

Answer 17

Avoid handling the cord to reduce vasospasm

Manually elevate the presenting part by lifting the presenting part off the cord by vaginal digital examination

Encourage into left lateral position with head down and pillow placed under left hip OR knee-chest position. This will relieve pressure off the cord from the presenting part.

Consider tocolysis (e.g. terbutaline) – if delivery is not imminently available this will relax the uterus and stop contractions, relieving pressure off the cord

Delivery is usually via emergency Caesarean section

Question 18

Discuss breech presentation

Answer 18

Buttocks/ feet first

Most common malposition is frank breech where baby’s hip joints are flexed and knees extended

Complete breech: baby’s knees and hips flexed

Footling breech: baby’s hip and knee joints extended and flexed respectively

Question 19

Management of breech presentation

Answer 19

Babies <36 weeks may turn spontaneously so watch and wait

ECV if >36 weeks

Mother may have vaginal delivery but access for conversion to emergency c-section needed

Vaginal = safer for mother

C-section = safer for baby

Question 20

What medication is used to promote efficacy of ECV?

Answer 20

Tocolysis: terbutaline

Given subcut, it is a b-agonist and works to relax the myometrim and promote ECV success

Question 21

What is given to rhesus negative women before ECV is done?

Answer 21

Anti D because ECV is a sensitising event

Question 22

How do we decide how much anti-D to give before a sensitising event?

Answer 22

Kleihauer test - measure foetal Hb levels in the mother