Malpresentation, cephalopelvic disproportion, uterine rupture

Question 1

What is a malpresentation?

Answer 1

Malpresentation is the situation where a foetus within the uterus is in any position that is not cephalic - i.e. head down.

Malposition is any cephalic position other than occiput anterior.

Question 2

What is the most common malpresentation?

Answer 2

breech presentation, occuring in 3% of term births (the incidence is higher at earlier stages of gestation, however the tendency is to rotate to a cephalic presentation with time)
your baby’s bottom or feet are facing downwards - is breech

Question 3

What are the maternal factors of malpresentation?

Answer 3

pelvic inflammation
pelvic tumour / fibroid
arcuate or septate uterus
oligohydramnios
placenta praevia

Question 4

What are some foetal factors of malpresentation?

Answer 4

prematurity
multiple pregnancy
fetal malformation e.g. hydrocephalus
intrauterine death

Question 5

What are the various types of breech?

Answer 5

frank breech - hips flexed, legs extended at the knee (i.e. feet by ears) - 60-70%
flexed breech - also called complete - both legs flexed at hip and knee (i.e. legs crossed) - 30-40%
footling breech - at least one leg presents below the breech - < 1%; this type of breech presentation carries the greatest risk of cord prolapse

Question 6

What is an unstable lie?

Answer 6

When the presentation of the foetus changes from day to day the lie is said to be unstable.

Question 7

Why is unstable lie not a sinister sign?

Answer 7

the uterus is relatively flaccid and able to accommodate a lot of movement of the fetus.

Question 8

What is an unstable lie caused by?

Answer 8

• placenta praevia
• polyhydramnios
• prematurity
• subseptate uterus
• pelvic tumours such as fibroids and ovarian cysts

Question 9

What is a transverse lie?

Answer 9

not uncommon for the foetus to have a transverse lie until about the 32nd week of pregnancy. However if the foetus continues to adopt a transverse lie after this period then a possible cause should be determined

Question 10

What can a transverse lie occur in association with?

Answer 10

grand multiparity
polyhydramnios
prematurity
subseptate uterus
pelvic tumours such as fibroids, ovarian cysts
placenta praevia
multiple pregnancy
foetal abnormality

Question 11

What are the main dangers of a transverse lie?

Answer 11

Pre-term ruptures of membranes
Cord porlapse

Question 12

What is the incidence of a transverse lie?

Answer 12

1:320

Question 13

What is the aetiology of transverse lie?

Answer 13

prematurity
contracted pelvis
praevia
polyhydramnios
intrauterine fetal death
twins - very rare for both twins to be transverse lie unless conjoined
foetal abnormality

Question 14

What are the investigations for transverse lie?

Answer 14

uterus broad and symmetrical
no fetal pole in the pelvis
vaginal examination - forewaters or limb felt

Question 15

When should a woman with a diagnosis of transverse or oblique lie be admitted to a hospital and what should be excluded once in hopsital?

Answer 15

After 37 weeks
praevia
twins
foetal anomaly
pelvic tumour
polyhydramnios

Question 16

What therapies and management is available for oblique and transverse lie?

Answer 16

external version
stabilising induction
elective caesarian section
There is a risk of cord presentation and prolapse. Under such circumstances an immediate caesarian section is essential.

Question 17

What is the most common malposition?

Answer 17

Occipito posterior position

Question 18

What happens in occipito posterior position?

Answer 18

The head is usually incompletely flexed and the occipitofrontal diameter presents - ie a larger diameter is involved.

Question 19

How does the occipito posterior position occur?

Answer 19

Approximately 10% of labours begin this way, but many correct in labour. The shape of the pelvis, the strength of contractions and thus the presence of an epidural all influence this correction.

Question 20

What do people of occipito posterior position rotate to?

Answer 20

From LOP 65% rotate to OA, 15% rotate to OP and are delivered as “face to pubes” - this is more difficult due to the increased diameter - and 20% rotate to OT, which is incompatible with normal delivery. In this last case the management depends on the stage of labour - 5cm dilation of the cervix indicates the need for a caesarian section, full dilation might be managed with forceps

Question 21

What is the face presentation?

Answer 21

This is where the head is extended such that the face presents. The presenting diameter is submento-bregmatic, averaging 9.5 cm.

It occurs in 1 in 500 deliveries, and is less favourable than OP (occipitoposterior). Progress depends on the relative sizes of foetus and pelvis.

Question 22

What is the most favourable position of face presentation?

Answer 22

Mento-anterior

delivery may convert to OA in much the same way as OP, this can be assisted by manually flexing the head. Turning the head to mento-anterior has advantages.

Question 23

What is the incidence of face presentation?

Answer 23

Incidence: 1:500 deliveries

77% of face presentations are mento-anterior.

Question 24

What is the aetiology of face presentation?

Answer 24

prematurity
anencephaly
cord around neck
neck tumours
polyhydramnios
pelvic tumour
praevia
uterine anomalies

Question 25

What does the foetus often do in an extended position?

Answer 25

Often the foetus actively holds its head in an extended position; such an infant may voluntarily extend the neck after delivery.

Question 26

What happens in cases of cephalopelvic disproportion?

Answer 26

the occiput may become lodged on the pelvic brim, while the sinciput advances. This results in an arrested face presentation.

Question 27

What are the investigations for the face position?

Answer 27

This is generally made on vaginal examination in advanced labour.

Other diagnostic clues include:

S-shaped fetal spine
ovoid shaped uterus without fullness in the flanks
a deep groove is palpated between the back and occiput

Question 28

What is the management for the face position?

Answer 28

exclude:
foetal anomaly
contracted pelvis

check foetal size
careful assessment, monitoring
episiotomy usually required if vaginal delivery
in a mentoanterior presentation normal vaginal delivery should be the ideal; in cases of delayed second stage, forceps should be used
persistent mentoposterior makes vaginal delivery almost impossible