Malpresentation

Question 1

What is malpresentation?

Answer 1

Any non-vertex presentation. This may be of the face, brow, breech or some other part of the body if the lie is oblique or transverse

The lie refers to the long axis of the fetus in relation to the long axis of the uterus. The lie may be longitudinal, transverse or oblique. The presentation is that part of the fetus that is at the pelvic brim, in other words, the part of the fetus presenting to the pelvic inlet.

Question 2

What is malposition?

Answer 2

When the head, coming vertex first, does not rotate to OA, presenting instead as persistent occipitotransverse or occipitoposterior (OP).

The position of the fetus refers to the way in which the presenting part is positioned in relation to the maternal pelvis.

Question 3

Types of malpresentations

Answer 3

-Face
-Brow= wide diameter at pelvic inlet
-Breech

Question 4

Signs and symptoms of malpresentation

Answer 4

-Fetus moulding, caput

Question 5

Describe face presentation

Answer 5

-1 : 500 births
-Fetal head extends right back (hyperextended so that the occiput touches the fetal back)
-Associated with prematurity, tumours of the fetal neck, loops of cord around the fetal neck, fetal macrosomia and anencephaly
-Recognised only after the onset of labour and, if the face is swollen it is easy to confuse this presentation with that of a breech.
-The position of the face is described with reference to the chin, using the prefix ‘mento’. The presenting diameter is submentobregmatic (9.5cm)
-The face usually enters the pelvis with the chin in the transverse position (mentotransverse) and 90% rotates to mentoanterior so that the head is born with flexion
-If mentoposterior, the extending head presents an increasingly wider diameter to the pelvis, leading to worsening relative CPD and impacted obstruction
-A caesarean birth is usually required.

Question 6

Describe brow presentation

Answer 6

-1 : 700 and 1 : 1500 births
-Least favourable for delivery
-The presenting diameter is mentovertical, measuring 14 cm.
-The supraorbital ridges and the bridge of the nose will be palpable on vaginal examination.
-The head may flex to become a vertex presentation or extend to a face presentation in early labour.
-If the brow presentation persists, a caesarean birth will be required

Question 7

Epidemiology of breech presentation

Answer 7

-Fetus presenting bottom first (caudal end of fetus occupies lower segment)
-incidence is around 40% at 20 weeks, 25% at 32 weeks and only 3% to 4% at term.
-The chance of a breech presentation turning spontaneously after 38 weeks is less than 4%.
-At term, 65% of breech presentations are frank (hips flexed, knees full extended), with the remainder being flexed or footling (one or both feet come first with bottom at higher position)
=Footling breech carries a 5% to 20% risk of cord prolapse (higher perinatal morbidity)

Question 8

Risk factors/causes for breech presentation

Answer 8

-Idiopathic
-15% underlying factors affecting fetal motility or the vertical polarity of the uterine cavity:
=Multiple pregnancy
=Bicornuate uterus and uterine malformations (septate, didelphys)
=Fibroids
=Placenta praevia (prevents presenting part from engaging)
=Polyhydramnios (unstable lie, unable to engage) and oligohydramnios (unable to turn to vertex)
=Prematurity (due to increased incidence earlier in gestation)

=It may also rarely be associated with fetal anomaly, particularly neural tube defects
=Neuromuscular disorders (hypotonia of fetus)
=Autosomal trisomy.

Question 9

Types of breech

Answer 9

-Complete breech, where the legs are fully flexed at the hips and knees (tuck)
-Incomplete breech, with one leg flexed at the hip and extended at the knee
-Extended breech, also known as frank breech, with both legs flexed at the hip and extended at the knee (pike)
-Footling breech, with a foot is presenting through the cervix with the leg extended

Question 10

Mode of delivery for breech presentation

Answer 10

-External Cephalic Version (vaginal breech delivery with baby turned prior to the onset of labour
-Caesarean
-Vaginal
-Assisted vaginal

Question 11

Describe ECV (external cephalic version)

Answer 11

-All women with a breech presentation at term should be offered ECV unless there is an absolute contraindication
-It is good practice to offer ECV from 36 weeks in nulliparous women and from 37 weeks in multiparous women.
-The success rate is approximately 50%

Question 12

Absolute contraindications to ECV

Answer 12

-When caesarean delivery is required regardless of presentation (e.g., placenta praevia)
-Antepartum haemorrhage within the last 7 days
-Abnormal cardiotocograph
-Major uterine anomaly
-Ruptured membranes
-Multiple pregnancy (except delivery of second twin)
-Absence of maternal consent

Question 13

Relative contraindications where ECV might be more complicated

Answer 13

-Nuchal cord
-Fetal growth restriction
-Proteinuric pre-eclampsia
-Oligohydramnios
-Major fetal anomalies
-Hyperextended fetal head
-Morbid maternal obesity

Question 14

Procedure of ECV

Answer 14

-CTG, USS (potentially fasted and prepared for theatre in case of fetal distress)
-Most likely to be successful in parous women when the presenting part is free, the liquor volume is normal, the head is easy to palpate, and the uterus feels soft.
-A flexed breech is more likely to turn than an extended (frank) breech.

-Lie flat with a 30-degree lateral tilt.
-Betamimetic drug, to soften the uterus is associated with an increased success rate.
-Applying scanning gel to the abdomen allows easier manipulation and permits scanning during the procedure if required.
-The breech is disengaged if necessary, with the scan probe or hands.
-Then, attempts are made to rotate in the direction in which the baby is facing (i.e., ‘forward roll’).
=The fetal heart rate should be checked throughout the procedure.
-If a forward roll is unsuccessful, a backward ‘somersault’ can be tried.
-If the procedure is only partially successful (i.e., the ­fetus is converted to a transverse lie), the fetus should be returned to breech rather than leave it transverse.
-A CTG should be performed after the procedure is completed.
-Women who are rhesus D negative should undergo testing for fetomaternal haemorrhage and anti-D immunoglobulin should be offered.

Question 15

Caesarean section for breech presentation

Answer 15

-Planned caesarean section at term for breech presentation is associated with a small reduction in perinatal mortality compared with a planned vaginal birth.
-However, the decision to perform a caesarean section has important implications for future pregnancies, such as the risks of opting for vaginal birth after caesarean section, increased risk of complications in future caesarean sections and the risk of an abnormally invasive placenta

Question 16

Vaginal birth for breech presentation

Answer 16

-Antenatal assessment and counselling risks associated with vaginal breech birth.
=More complicated in: hyperextended neck on ultrasound, high/low estimated fetal weight, footling presentation, and evidence of fetal compromise.
-Induction of labour is not usually recommended if presenting in labour
-Epidural analgesia controversial—its use may facilitate manipulation of the fetus, but its presence may inhibit the desire to push, which is particularly important in breech delivery.
-Augmentation of slow progress should be considered only in the event of inadequate uterine activity in the presence of an epidural.
-A standing or semi-recumbent position in an ‘all fours’ position has been recommended.
-At full dilatation, the woman can be encouraged to push when she experiences an urge. The temptation to pull must be resisted.
-Ideally, the baby should be left alone to birth by itself (‘hands off’), taking care to ensure that the back remains uppermost when advancing.
-If there is undue delay, or there are concerns about fetal well-being (e.g., movements stopping, baby becoming floppy, no response to stimuli), assisted delivery can be used to encourage a more rapid birth.
-Breech extraction may be considered when delivering the second twin

Question 17

Technique for vaginal breech presentation

Answer 17

-Knees flexed to deliver legs
-Once legs are delivered, wait for body to advance further before holding bony pelvis firmly-Rotate to allow one arm to be freed, flexed and brought down
-Rotation the other way allows other arm to be delivered
-After delivery of other arm, flexion of baby’s head encouraged by allowing the breech to hang down
-Head delivered as for hands off delivery

Question 18

Describe the assisted vaginal breech birth

Answer 18

-One of the key risks of breech delivery is that pulling may lead the head to extend and become stuck at the pelvic brim. ‘The importance of maternal effort at this stage, rather than traction from below, cannot be overemphasised—it allows the head to flex and minimises the risk of it becoming stuck at the pelvic brim’.
-Should the head of a pre-term breech become entrapped behind an incompletely dilated cervix, it should first be flexed as far as is possible to narrow the presenting diameter.
-Failing this, the options are then to incise the cervix at the 4 and 8 o’clock positions (risking massive, potentially fatal maternal haemorrhage) or to push the fetus back up and perform a caesarean section (a very difficult manoeuvre).
-Because such interventions are hazardous to the woman, it may be preferable to await spontaneous birth even if this compromises the well-being of the baby.
-All babies presenting by the breech should be examined for developmental dysplasia of the hip and Klumpke paralysis.

Question 19

Risk factors and complications of transverse and oblique lie

Answer 19

-Occurring in less than 1% of pregnancies at term
-There is usually no specific cause, but abnormal lie is more common in multiparous women, multiple pregnancies, pre-term labour and polyhydramnios.
-It may also be associated with placenta praevia, congenital abnormalities of the uterus, lower uterine fibroids and other pelvic masses, such as an ovarian cyst

Question 20

Management of transverse lie

Answer 20

-Identified antenatally
=scan should be undertaken to exclude placenta praevia, polyhydramnios, lower uterine fibroids and a pathologically enlarged fetal head
-ECV is usually possible (the woman should be reviewed a few days later to ensure that the lie is still cephalic).
-She should be advised to come to hospital if there is any suspicion of early labour, as it may still be possible to carry out an ECV at that stage, provided that the membranes are still intact.
-She should also be advised to go to the hospital immediately if there is any suspicion of membrane rupture, as there is a risk of cord prolapse or prolapse of a limb
-In view of the small risk of cord prolapse, some clinicians advise that women with a transverse lie or unstable lie are admitted to hospital from 38 weeks to await birth or until a longitudinal lie is maintained.

-In labour: particularly after membrane rupture, a caesarean section will usually be required.
=These caesarean sections can be technically very difficult, and a vertical uterine incision may be necessary to allow adequate access for delivery.

Question 21

Management of unstable lie

Answer 21

-A lie that varies rom examination to examination

-Manage conservatively, with repeated ECVs as required, and await the spontaneous onset of labour. Should the membranes rupture with the fetus in a non-cephalic presentation, there may be a risk of cord prolapse. As described earlier, inpatient care is considered appropriate by some.
-Arrange to turn the baby to cephalic presentation and then induce labour. This is sometimes referred to as a ‘stabilising induction’. The disadvantage is that the induction itself is not without risks, and the lie may become unstable again even after the membranes have been ruptured.
-Carry out a caesarean section.

Question 22

Types of malposition

Answer 22

10% of pregnancies, the fetal head enters the pelvis in a more OP position than transverse or anterior, either by chance or in association with an unfavourably shaped pelvis, particularly the long oval ‘anthropoid’ pelvis. The baby is then in a direct OP position or with the occiput to the right or left of the midline, referred to as right or left OP.

1. The occiput will rotate anteriorly (through approximately 135 degrees) to OA, and then (usually) deliver normally (65%).
2. The occiput will partially rotate to occipitotransverse and not deliver (20%).
3. The occiput will rotate more posteriorly to OP (15%).

Question 23

Differences in malposition vaginal delivery

Answer 23

-Those that remain OP have greater difficulty negotiating the birth canal and are less likely to birth spontaneously.
-The first and second stages of labour are usually longer, partly because of the greater presenting diameter (relative CPD) and partly because the head is less well applied to the cervix and, therefore, less able to facilitate its dilatation.
-Back pain in labour appears to be more common with the OP position.
-The woman is more likely to request an epidural, is more likely to experience secondary arrest due to relative CPD, and is more likely to require augmentation with an oxytocin infusion.

Question 24

Management of malposition delivery

Answer 24

-If the cervix does not reach full dilatation despite oxytocin augmentation, a caesarean section will be required.
-If full dilatation is reached, it is quite possible for a baby to be born in the OP position (with the head coming out ‘face to pubis’).
-Not uncommonly, manual rotation, rotational Ventouse, or a Kielland rotational forceps birth will be required
-Third- and fourth-degree perineal tears are more likely to occur when a baby is born in an OP position

Question 25

Pre-term breech management

Answer 25

For those in pre-term labour with breech presentation, the mode of delivery should be individualised. The decision should be based on the stage of labour, type of breech, fetal well-being, and the availability of a clinician experienced in vaginal breech birth

Question 26

What is CPD?

Answer 26

-Cephalopelvic disproportion
=How well the fetal head fits through the pelvis and may occur if the fetal head is too big or the pelvis too small.
-It is subdivided into ‘true’ CPD if the head is in the correct position (head too big or pelvis too small) and ‘relative’ CPD if the obstruction is caused by malposition (increases the diameter of presenting part)

-True CPD diagnosed only if head does not become engaged despite adequate uterine activity

Question 27

Investigation of breech presentation

Answer 27

-Clinical examination: fetal head felt in upper part of uterus, irregular mass in pelvis (buttocks and legs), vaginal: sacrum or foot may be felt through cervical opening
-Fetal heart auscultated higher on maternal abdomen
-USS
=Document fetal lie and presenting part, type of breech, degree of flexion of head, estimated fetal weight (3.8kg), amniotic fluid volume, placental location, fetal anatomy review

Question 28

Risks with vaginal breech birth

Answer 28

-Head obstruction of baby during labour
=Intracranial injury=Widespread bruising
=Damage to internal organs
=Spinal cord transection
=Umbilical cord prolapse
=Hypoxia

-Maternal: emergency C section higher risk than planned