1. Bleddyn Woodward 4th year medical student
Abnormal Labour
Bleddyn Woodward
4th year medical student

2. Labour dystocia Definition: Abnormal or inadequate progress in labour.
Also known as “failure to progress”.

3. Aetiology Powers Passage Passenger Labour dystocia
Inefficient uterine contractions
Passage
Mechanical interference with the passage of the fetus through the birth canal
Passenger
Abnormalities of the foetus e.g. malpresentation, abnormal lie

4. Powers Inefficient uterine activity
Aetiology: dysfunctional uterine contractility, unclear reason.
Clinical features - Abnormalities of the 1st stage
Prolonged latent phase (>20h in nulliparous women)
Prolonged active phase (cervical dilation < 1 cm/h OR rate of descent of fetal head < 1 cm/h)
Secondary arrest of cervical dilation

5. Powers Management: Rule out Cephalopelvic disproportion.
Wait for active phase to begin. OR
Augmentation: ARM/oxytocin.
Caesarean if this fails.

6. Passenger Lie - relationship of fetus to long axis of uterus
Longitudinal = normal
Presentation - the part of the fetus that occupies the lower segment of pelvis
Cephalic = normal
Attitude - degree of flexion of the head on the neck
Fully flexed = normal
Position - degree of rotation of the head on the neck
OA = normal

7. Breech Incidence: Risk factors: Commonest malpresentation.
3-4% of singleton pregnancies at term.
Risk factors:
Maternal:
Grand multiparity → uterine laxity
Uterine abnormalities e.g. septate uterus
Pelvic tumours/bony abnormalities preventing engagement of head.
Placental:
Placental praevia
Oligohydramnios/ polyhydramnios
Fetal:
Multiple pregnancy

8. Breech Clinical features: Investigations: Management:
↑risk of cord prolapse
preterm labour
birth trauma (fetal head can get trapped in pelvis, maternal morbidity.
Investigations:
Suspected on clinical examination.
Ultrasound confirms presentation
Management:
External cephalic version – successful in ~50% of cases.
Elective caesarean – at 39 weeks. Normal vaginal delivery not recommended.

9. Occipitoposterior position
Incidence: 10% of pregnancies
Clinical features:
Delivery is usually prolonged and difficult for mother.
The head may rotate to OA position as it enters the pelvis leading to normal delivery.
It may rotate to full OP position/ OT position and require forceps delivery.
5-10% require caesarean section.

10. Transverse/oblique lie
→ shoulder presentation
Incidence: 0.3% of term pregnancies
Risk factors:
Placenta praevia/uterine or pelvic anomalies preventing engagement
Grand multiparity (lax uterus)
Management:
ECV
Caesarean section if unsuccessful

11. Face/brow presentation
Incidence:
Face =1 in 500 births, usually occurs by chance.
Brow = 1 in 1500 births.
Management:
Operative vaginal delivery may be possible.
Otherwise caesarean section.

12. Passage Cephalopelvic disproportion Definition:
Cephalopelvic disproportion is diagnosed when a woman has been unable to deliver a fetus despite:
adequate uterine activity and
no malposition of the fetus
Incidence: Uncommon in the UK.

13. Passage Aetiology: Management: Macrosomia
Small/abnormally shaped pelvis
Management:
Trial of delivery may be possible
30% then require instrumental delivery
30% require caesarean section
Otherwise, elective caesarean

14. Shoulder dystocia Incidence: rare Aetiology:
Fetal head is born but the shoulders cannot be delivered because of failure of rotation of the shoulders to enter the transverse diameter of the pelvic brim.

15. Shoulder dystocia Management: Prognosis:
Obstetric emergency – fetal demise can occur due to entrapment of the cord.
H: call for help
E: pt. evaluated for episiotomy
L: Mc Roberts position. Legs hyperextended onto abdomen
P: Suprapubic pressure applied to the back of the fetal shoulder
E: Enter- to manually rotate or perform Woods Screw Manoeuvre
R: Remove the posterior arm
R: Roll over onto all fours
Prognosis:
Maternal: damage to the lower genital tract is common
Baby: brachial plexus injury (Erb’s palsy), fractured clavicle/humerus

16. Cord prolapse Cord lies lower than the presenting part.
1 in 300 deliveries
Obstetric emergency – fetal blood supply is compromised
Management:
Cervix > 9cm dilated, immediate instrumental delivery may be possible.
Cervix < 9cm dilated, caesarean section.

17. References
Pocket Essentials of Obstetrics and Gynaecology, Barry O’Reilly, Cecilia Bottomley, Janic Rymer. Elsevier Saunders 2005.
Oxford Handbook of Clinical Specialties 8th Ed., J Collier, M Longmore, T Turmezei, A. R. Mafi. Oxford University Press, 2008.
Fundamentals of Obstetrics and Gynaecology 8th Ed., J Oats, S Abraham. Mosby, 2004.