This document discusses fetal positioning and presentations during labor. It begins by defining presentations other than vertex, such as breech, face, brow, and transverse. It then lists potential risk factors for abnormal presentations. The main part of the document describes the different positions a fetus can take during labor, including occiput posterior. It provides details on identifying and managing different positions and presentations, including mechanisms of labor, signs and symptoms on examination, and potential interventions if needed.

2. Fetal presenting part other than vertex includes
breech, face, brow, transverse, and compound
presentation.

3.  More than one pregnancy (e.g. Multipara,Grand multipara )
 More than one fetus (e.g. Twins)
 Too much or too little amniotic fluid (e.g. Polyhydramnious,
oligohydramnios)
 Abnormal uterine shape (e.g. Arcuate ,septate, supseptate) or
abnormal growth (e.g Fibroid)
 Placenta previa
 The baby is preterm

4. Presentation
the part of the fetus which occupying the
lower uterine segment
Presentation may be :
(3%)
(0.5%)
Breech
Face
Brow
Shoulder
Compound
3 in 100
1 in 500
1 in 1000
1 in 300
1 in 1000
(0.3%)

6. Vertex 99% Face
Brow

8.  The occiput is in the posterior segment of pelvis,
overlying the sacroiliac joint or the sacrum
 Occipitoposterior position is responsible for most cases
of prolonged labour and second stage delay and is the
most common cause of a mobile head at term
 When the occiput is in front of the sacrum, it is termed
direct Occipitoposterior
 In the right Occipitoposterior, the occiput overlies the
right sacroiliac joint and in left Occipitoposterior, it
overlies the left sacroiliac joint
 Thus,3 positions are described –ROP, LOP, Direct
Occipitoposterior

11.  1. BACK ON THE RIGHT SIDE
 If the back is to the left as in 70% of vertex presentations, the
chance of a posterior position(LOP) is remote
 this is because of dextrorotation of uterus and the presence of
sigmoid colon on the left
 the foetal back is seen on the right side in 25-30% of vertex
presentations and this predisposes to occipitoposterior(ROP)
 2. ANTERIOR INSERTION OF PLACENTA
 Favours a posterior position by pushing the back of the head
with the broader biparietal diameter posteriorly

12.  3. SHAPE OF THE BRIM
 Influences position
 In anthropoid pelvis, the anteroposterior diameter of
the brim exceeds the transverse diameter
 This pelvis is usually of high assimilation type with an
extra vertebra in the sacrum
 Therefore, inclination of the pelvis is increased and this
favours Occipitoposterior
 In android pelvis, the inlet is wedge shaped and so the
bulky occiput cannot find space in the narrow forepelvis
 This also predisposes to Occipitoposterior

13. ABDOMINAL EXAMINATION
 Subumbilical flattening due to the absence of the back
anteriorly
 Back is in one or the other flank and so cannot be felt
clearly
 Limbs are felt easily anteriorly
 Shoulder is felt out in the flanks
 Unengaged or high head at term
 The sinciput and occiput may be at the same level due
to deflexion
 Fetal heart sounds are heard in the flanks and are
frequently indistinct

14. VAGINAL EXAMINATION
 Early in Labour
 Early rupture of conical bag of membranes
 Sagittal suture in the right oblique diameter of the
pelvis
 Smaller posterior fontanelle in the right posterior
quadrant and diamond shaped larger anterior
fontanelle in the left anterior quadrant
 As the head is deflexed, both fontanelles are easily
palpated

15. In occipitoanterior position, as the head is well
flexed, the posterior fontanelle will be easily
felt, but not the anterior fontanelle
On the other hand, in Occipitoposterior, the
head is usually deflexed and so the anterior
fontanelle will also be felt with ease

16.  LATE IN LABOUR
 A large caput may be present obscuring the sutures
 The pinna always points the occiput
 Perineum gapes much before the head distends it
and premature straining can occur
 Difficulty in applying forceps in unrecognised
occipitoposterior

17. Occipitoposterior position is the common
cause for prolonged labour in a vertex
presentation
The mechanism of labour will depend upon
whether the vertex is well flexed. in
occipitoposterior position with a well flexed
head, the occiput being the lower will touch the
pelvic floor first and rotate anteriorly and
labour proceeds normally

18. However due to the longer internal rotation in
occipitoposterior(3/8 of a circle) labour will
naturally be prolonged
In some occipitoposterior positions, the head is
deflexed and this may result in further delay in
rotation or malrotation

19. Deflexion may be due to when the back is
posterior, the convexity of the fetal spine abuts
against the convexity of the maternal spine causing
extension of the head
Hence large diameter present to the pelvic inlet
and the occiput is no longer the leading part. This
is also known as relative disproportion
Another problem is that in OPP, the biparietal
diameter occupies the smaller sacrocotyloid
diameter which is encroached upon by the sacral
promontory
And hence the labour is further arrested

20. Suboccipitofrontal diameter in a deflexed head
is 10.5cm
Occipitofrontal diameter in a head which is
further deflexed is 11.5cm

21.  1. Anterior rotation
 In 90% of cases, the occiput rotates anteriorly through
3/8of a circle and the baby is born as occipitoanterior.
Engagement may be delayed and labour may be longer
because of the dorsiflexion
 2. Posterior rotation and face to pubis delvery
 When the head is deflexed, the engaging diameter is the
occipitofrontal and sinciput is the leading part. Hence
the sinciput touches the pelvic floor first and rotates
anteriorly. The occiput thus rotates posteriorly into the
hollow of sacrum and delivery occurs as face to pubis.
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22.  Perineal tears are common as the occiput is
posterior and it is the longer biparietal
diameter(9.4), which distends the perineum rather
than the smaller bitemporal(8cm). Hence liberal
episiotomy should be given.
3. Failure of rotation
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ittal suture
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23. REASONS FOR FAILURE OF ROTATION
 Deflexion of the head
 Inefficient uterine contraction
 Weak pelvic floor preventing anterior rotation
 Cephalopelvic disproportion and android
pelvis

24. Most of the malposition will rotate anteriorly and
the baby will be born spontaneously as occiput
anterior
Alternatively, the may rotate posteriorly and
deliver as face to pubis which need liberal
episiotomy.
As the labour is longer, judicious use of fluids and
analgesia is needed.
Epidural analgesia is ideal.

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26. 1. CAESAREAN SECTION
 The pelvis should be reassessed and if the pelvis is
android or there is evidence of disproportion,
CAESAREAN SECTION should be done
 Increasing use of caesarean for deep transverse
arrest is to avoid the intracranial haemorrhage due
to traumatic vaginal delivery

27. 2. VACCUM EXTRACTION
 This is an alternative in the absence of
cephalopelvic disproportion.
 It promotes flexion thereby reducing the diameter
presenting to the outlet from occipitofrontal to
smaller suboccipitobrgmatic.
 It is less traumatic and does not need general
anaesthesia
 The cup should be applied as near posterior
fontanelle as possible as in order to promote flexion
and smooth descent .

28. 3. MANUAL ROTATION
 This procedure can be employed if the obstetrician
is well versed in this technique.
 Under the general anaesthesia, the right hand
grasps the sinciput displacing it thereby increasing
flexion.
 The smaller bitemporal diameter allows more space
for the thumb and finger to have a firm grasp
across the temple with middle finger on the frontal
suture. In LOP, the left hand is used. Then the
sinciput is rotated and forceps or vaccum is applied

29. 4. FORCEPS ROTATION
 In deep transverse arrest Keilland forceps is used.
 It should be used only by the obstetrician who are
expert in its use.
 It is widely used in UK but it is not popular in India.
 Keilland forceps is applied under General
Anaesthesia in the anteroposterior direction and
rotation carried out

31.  This is a cephalic presentation where the attitude is one
of complete extension, presenting part is the face (area
between chin and glabella)and denominator is the chin
or mentum.
 Primary face presentation: present before the onset of
labour and are rare
 Secondary face presentation: caused by extension
during labour.( E.g. . left mentoanterior is a result of
extension of right Occipitoposterior)

32. The engaging diameter is submentobregmatic
9.4 cm

34. Maternal
 Contracted pelvis
 Oblique of uterus
 Multiparity and pendulous abdomen
Fetal
 Anencephaly and iniencephlaly
 Cord round neck
 Tumor of neck like congenital goiter
 Spasm of sternocleidomastoid muscle
 Dolichocephalic head

35. Abdominal examination
 In mentoanterior, back is felt with difficulty as it is
posterior and limbs are felt anteriorly
 Head remains high
 Cephalic prominence is the occiput and on the
same side as the back
 Groove between the head and back is prominent
 Fetal heart sound are transmited through the chest
and heart well anteriorly in mentoanterior

36. Vaginal examination
 Conrical bag of membranes
 Chin, mouth, nose, mala eminences, and
supraorbital ridges are felt
 In mentoanterior, chin is in one anterior quadrant
and forehead in the opposite posterior quadrant

37. Mentoanterior posterior
1. Engagement
 the engagement diameter is submentobregmatic.
In face presentation, the biparietal diameter is 7 cm
behind the face unlike in vertex, where it is only 3-4
cm distance.
 The biparietal diameter will pass through the inlet
only when the face is low down in the perineum.
When the face is distending the vulva (crowning),
the head has just engaged.

38. 2. Descent with increasing extension
 Descent is brought by the same factors as in vertex
presentation.
 When resistance is encountered by a process of
extension, the occiput is pushed towards the back
of the fetus, while the chin descents.

39. 3. Internal rotation
 On further descent, the chin reach
0
es the pelvic floor
and rotates anteriorly through 45 towards the
symphysis.
 Anterior rotation does not take place until the face
is well applied to the pelvic floor and may be
delayed. Only internal rotation takes place this
manner, can the neck travers the posterior surface
of the symphysis pubis.

40. 4. flexion
 The head is born by flexion. The chin pivots under
the symphysis pubis and the mouth, nose, orbits,
forehead, vertex and occiput are born by flexion
5.Restitution and external rotation
 Restitution and external rotation of chin occurs
towards the side to which it was originally directed,
and the shoulder are born as in vertex

41. Mentoposterior position
2/3 of cases anteriorly through 3/8 of a circle
and deliver as mentoanterior. Of the rest, some
remain in the oblique diameter and some
rotate posteriorly into the hollow of sacrum.
In these cases of persistent mentoposterior, the
neck is too short to span the 12cm of the
anterior aspect of sacrum.

42. The shoulder also get impacted along with the
head making delivery impossible.
The engaging diameter is the sternobregmatic,
which is about 17cm. Hence, there is no
mechanism of labour in mentoposterior

43. Cause of prolonged labour in face
 Face is less effective dilator of cervix
 No moulding of face
 More chance of premature rupture of membrane
 Long internal rotation in mentoposterior
 Internal rotation occurs only late in the second
stage

44. complication
 prolonged and complicated labour
 Maternal distress … dehydration …
Infection
 obstructed labour → uterine rupture
 →maternal death
Fetal
complication
Rupture of fetal membranes
cord prolapse → fetal distress →fetal death
edema of the brow
marked moulding , congenital malformation
Increase in maternal and fetal morbidity and mortality
Maternal
complication

45. Evaluate the cephalopelvic disproportion or
other associated complication and in such
situation, caesarian section is done.
If there is no disproportion and position is
mentoanterior, labour can be allowed to
progress.
In persistent mentoposterior, cescerian section
is done.

47. It is the least common among cephalic
presentation and most unfavorable.
The attitude is one of partial extension , the
presenting part being the area between the
anterior fontanelle(bregma) above and the
glabella and orbital ridges bellow and
denominator is the forehead or frontum.

48. The presenting diameter is verticomental 13.5
cm, which is largest of fetal head

49. It is about 1in 1000 birth
The cause is similar to face presentation and
include any factor that interferes with flexion of
the head

50. Possible Etiological causes
Maternal
Fetal
BPriceomrnaatuterituyterus
SMeuplttieptleutgeersutsation
F
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ra
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r nios N
La
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F
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soid
pelvis Large Fetal head
Congenital Abnormalities
Cord around the neck
Neck tumor

51. - Left fronto-anterior.
 - Right fronto-anterior.
- Right fronto-posterior.
 - Left fronto-posterior.

52. Abdominal examination
 High mobile head, which feels large from side to
side
 Cephalic prominence is the occiput and is on the
same side as the back and the groove between the
cephalic prominence and the back is less prominent
than in face presentation

53. Vaginal examination
 Conical bag of membrane may be felt in early
labour
 Anterior fontanelle(bregma) is felt at one end and
root of nose(nasion)and orbit ridges at the other
end of an oblique or transvers diameter.
 Sometimes, the nose and the mouth are palpable,
but not the chin.

54. As such, ther is no mechanism of labour for
persistent brow presentation.
Spontaneous delivery is unlikely and can occur
only when there is a very small baby and large
pelvis.
In persistent brow, the verticomental diameter
is shortened and the occipitofrontal diameter is
elongated with marked moulding and a large
catput on the forehead

56. complication
Increase in maternal and fetal morbidity and mortality
Maternal complication
prolonged and complicated labour
Maternal distress … dehydration … keto acidosis
Infection
No engagement of presenting part
obstructed labour → uterine rupture →maternal death
fetal complication
Rupture of fetal membranes
cord prolapse → fetal distress →fetal death
marked molding

57. Antepartum
 It is better to wait until the onset of labour in the
hope that correction to vertex or face.
Early labour
 Cesarean section should be done. If diagnosis in
early labour before rupture of membrane, a short
period of time can be given under close supervision
in the hope of spontaneous correction.

58. Late labour
 It there is feature of obstructed labour, cesarean
section is performed immediately even if the fetus is
dead.