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Week 2: Complex labour > Malposition and malpresentation > Flashcards

Malposition and malpresentation Flashcards

1
Q

What is malposition?

A

Where the occiput is in one or other posterior quadrant of the pelvis’ The fetus adopts a deflexed attitude as in an OP position

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2
Q

What is malpresentation?

A

any presentation other than vertex The fetus adopts an extended attitude as in face or brow, or presents as breech or shoulder

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3
Q

What is the lie?

A

the relationship of the long axis of the fetus to the long axis of the uterus

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4
Q

What is the presentation?

A

the part of the fetus lying in the lower pole of the uterus

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5
Q

What is the position?

A

-The denominator is the part of the presentation used to determine the position

Occiput, sacrum, mentum (chin)

-The position is the relationship of the denominator to six areas of the woman’s pelvis

Left and right of all three

Plus whether it is an anterior or posterior position

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6
Q

What is the attitude?

A

The relationship of the fetal head and limbs to its body. May be flexed, deflexed or partially extended

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7
Q

State diameters of fetal skull and presenting part

A
  1. Suboccipitobregmatic 9.5cm, normal, well flexed
  2. Suboccipitofrontal 10cm, not quite flexed
  3. Occipitofrontal 11.5cm, deflexed, military, OP
  4. Mentovertical 13.5cmm, brow
  5. Submentobregmatic 9.5cm, face
  6. Submentovertical 11.5cm, face not fully extended

(Biparietal 9.5cm- widest transverse diameter and bitemporal 8cm)

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8
Q

State diameters of maternal pelvis

A
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9
Q

What is the normal mechanism of labour?

A

Descent/engagement

Flexion

Internal Rotation (of head-to suit change in diameter of maternal pelvis- becomes dead on AP, coz was preiously Loa or Roa)

Crowning of the Head/Extension

Restitution (head realigns with shoulders- they’re diagonal not completely vertical to pelvis)

External Rotation of the Shoulders (shoulders become dead on AP and are visible)

Lateral Flexion (posterior then anterior shoulder and trunk delievered)

Expulsion

Do Frogs In Canada Ride Epic Limos Everyday?

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10
Q

Why is knowing the position and presentation important?

A

Impacts greatly on care plan- is vaginal birth possible, c-section necessary, ECV?

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11
Q

Why does OP occur?

A

Passengers

Powers

Passage

Maternal posture and lifestyle

Android/anthropoid pelvis

Anterior placenta

Epidural analgesia plus oxytocin augmentation

Nulliparity

Increased maternal age

Increased gestation

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12
Q

Evidence on optimal fetal positioning

A

Research Evidence

Inconclusive

Further research recommended

May help as a comfort measure in labour

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13
Q

What clinical assessment is undertaken for the diagnosis of OP position?

A

Antenatal assessment

  • Inspection of abdomen
  • Palpation
  • FH auscultation

In labour

  • Listen to the woman (FM and pain)
  • Inspection and palpation
  • FH auscultation
  • Vaginal examination
  • Progress of labour (e.g. early SROM, in-coordinate contractions
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14
Q

What is the mechanism of occipito position – long rotation

Long internal rotation (commonest mechanism) ie LO

A

Long internal rotation (commonest mechanism) ie LOP

Occipito frontal diameter engages (11cms) in R oblique diameter

(12cms)

Increasing flexion and descent- Sub-occipito bregmatic diameter (9.5cms) in the pelvic cavity

Occiput meets the resistance of the pelvic floor and rotates 3/8th circle forwards

Head now in same position as occipitor anterior mechanism

The shoulders follow the head turning 2/8th

from left to right oblique

Head is born by extension

Restitution

Internal rotation of shoulders

External rotation of head to mothers right

Lateral flexion

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15
Q

Short internal rotation (Persistent OP)

A

Occipito frontal diameter (11cms) engages in right oblique diameter (12cms)

Descent occurs with little or no flexion

Sinciput meets the resistance of the pelvic floor and rotates forwards 1/8th of a circle (now direct OP)

Occiput passes into the hollow of the sacrum

Shoulder enters pelvis in left oblique

The root of the nose (glabella) pivots under the pubic arch

Occiput sweeps the pelvic floor by flexion and face is born by extension (‘face-to-pubes’)

Restitution

External rotation of head

Lateral flexion

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16
Q

What is the mechanism of OP – Deep transverse arrest?

A

Head descends with some flexion

Head starts long rotation but flexion not maintained and head caught in bi-spinous diameter (11cms) of the outlet in deflexed position

Head cannot advance and an instrumental or operative delivery will be necessary

17
Q

What is the midwifery management and care during labour?

A

Check notes and history, Identify early, women with OP position, Abdominal palpation – accurate diagnosis

Full and clear explanation to woman re labour, length, options, discomfort, provide full support

Discuss optimal fetal positioning and alternative birth positions

Monitor maternal and fetal wellbeing – strength and length of contractions and descent of head abdominally. FH.

Check bladder

VE – findings – essential to confirm. PROGRESS? Large caput?

Observe for early ROMs, - risk of cord prolapse

Monitor for in-coordinated uterine action, and cervical dilatation and provide active management of labour for positive outcome – get head flexed!

Augment labour if appropriate

Avoid epidural if possible – mobile mix

RECORDS of progress and subsequent care

Inform woman of progress being made and possible outcomes

18
Q

What are the 5 possible outcomes of an OP position?

A

Depends on the degree of flexion

90% will descend and rotate OL-OA and deliver

  1. deflexed head – long rotation to OA
  2. deflexed head – long rotation but DTA – assisted delivery
  3. deflexed head – short rotation to DOP
  4. High deflexed head – partial extension – brow
  5. Full extension - face
19
Q

What is the management of a face to pubes delivery?

A

Allow the sinciput to escape as far as the glabella (smooth part of the forehead above and between the eyebrow)

The occiput sweeps the perinuem, the sinciput is held back to maintain flexion

Grasping the head to bring the face down from under the symphysis pubis

Extension of head

20
Q

Who can perform a manual rotation of OP position?

A

A skilled practitioner

21
Q

What ar the possible complications of OP position?

A

Increased maternal and perinatal morbidity and mortality due to…

  • Obstructed labour if DTA or Brow
  • Maternal exhaustion and ketosis
  • Higher incidence of epidural and instrumental delivery or C/S
  • Maternal trauma –probable need for episiotomy third /fourth degree Urinary retention – epidural, pressure, prolonged labour
  • Cord prolapse with early ROMs
  • Excessive moulding with long labour
  • Intracranial haemorrhage with upward moulding of fetal skull
  • Fetal hypoxia with prolonged labour
  • PPH with prolonged labour
  • Maternal/fetal infection due to intervention in a prolonged labour
  • Postnatal depression or PTSD due to above (Lewis 2010)
22
Q

What are the causes of a face presentation?

A

Face occurs when the presenting part and head is hyper-extended

Incidence 0.2%

Causes:

Pelvis shape

Grand multiparity (pendulous abdomen)

Polyhydramnios

Enlargement of fetal neck (tumour of the neck)

Multiple coils of cord around the neck

Anecephalic fetus

Multiple pregnancy

Prematurity

(Lewis 2010, )

23
Q

How is a face presentation diagnosed?

A

Primary (Before Labour)

Not easily identified before labour

Non-engaged head

Deep groove between head & back palpable

Secondary (During Labour)

Most commonly detected on VE

Presenting part high, soft and irregular

Eyes, nose & mouth may be felt

Need to differentiate from breech

Facial features more difficult to palpate as labour progresses due to facial oedema

24
Q

What is the mechanism of labour for a face presentation?

A

6 possible positions for face presentation

Mentum (chin) is the denominator

Presenting diameter is 9.5cm

Needs to rotate to a mento-anterior position to facilitate a vaginal delivery

There are no delivery mechanisms for persistent mento-posterior positions therefore a vaginal delivery is very unlikely

25
Q

What is the mechanism of mento-anterior position?

A

Descent with extension of the head

Mentum- leading part

Internal rotation of the head- chin reaches pelvic floor & rotates 1/8th circle forward

Chin escapes under symphysis pubis

Flexion of head- sinciput, vertex & occiput sweep perineum

Restitution- mentum turns 1/8th circle to original side of back

Internal rotation of shoulders (anterior shoulder rotates 1/8th of a circle)

External rotation of head simultaneous with shoulders

Lateral flexion

26
Q

What are the complications with face presentation?

A

Cord prolapse

Obstructed labour

Fetal distress

Operative delivery

Severe perineal trauma

Facial bruising & oedema in baby

Intracranial bleed in baby

27
Q

What is a brow presentation?

A

Brow presentation involves partial extension of fetal head with the frontal bone as the presenting part

Least common of all presentations

Incidence 1:500 – 1:1400

Causes similar to face presentation

28
Q

What is the mechanism of labour in a brow presentation?

A

Presenting diameter (mentovertical) 13.5cm

Vaginal delivery extremely rare

Obstructed labour normally results

Delivery usually by LSCS unless baby very small

Three possible outcomes

Brow may:

  • Convert to vertex
  • Convert to face
  • Remain as a persistent brow
29
Q

What is the management of care with a brow presentation?

A

Immediately inform Obstetrician

High risk care

If diagnosed early in labour & no fetal distress, obstetrician may wait to see if conversion to vertex or face takes place or LSCS

30
Q

What are the complications with a brow presentation?

A

Cord prolapse

Fetal distress

Excessive moulding

Obstructed labour (very likely)

31
Q

What causes an unstable lie, how is it diagnosed, when can you continue as normal and when does it become an obstetric emergency?

A

An unstable lie (transverse or oblique) can lead to a shoulder presentation

  • Causes: laxity of uterine muscles, multiple pregnancy, polyhydramnios, placenta praevia, fibroid
  • Diagnosed by abdominal palpation
  • Can be corrected by external version to a longitudinal lie
  • If fetal head enters the pelvis labour can continue as normal.
  • If shoulder enters the pelvis once labour has started then this is an obstetric emergency and need delivery by LSCS

Week 2: Complex labour (5 decks)

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