By Arambam.Aruna

posterior

position

Occipito

Definition:In a vertex presentation where the

occiput is placed posteriorly over the sacro iliac joint or directly over the sacrum, it is called an occipito posterior position

INCIDENCE

- 10% at onset of labour.- During pregnancy(30-40%)- Early in labour(10-20%)- Late in labour(1-2%)

POSITION

Right OP is common than left OP because

- Dextro rotation of the uterus- Diminished left oblique

diametre by the presence of sigmoid colon

The right oblique diameter is slightly longer than the left one.

Aetiology

The shape of the pelvis: (85%)anthropoid and android pelvises are the most common cause of occipito-posterior due to narrow fore-pelvis.

Others(15%) Maternal kyphosis: The

convexity of the foetal back fits with the concavity of the lumbar kyphosis.

High pelvic inclination Abnormal uterine

contraction Anterior insertion of the

placenta: the foetus usually faces the placenta (doubtful).

Fetal factor contributing to deflexion of head e.g brachy cephaly

Other causes of malpresentations: as – placenta praevia,

– pelvic tumours,

– pendulous abdomen,

– polyhydramnios,

– multiple pregnancy.

Idiopathic(10-30%)

Type

Primary: It occure late in pregnancy before the onset of labour. It occur in association with anthropoid pelvis

Secondary: It develops during labour and in association with android pelvis

ANTENATAL DIAGNOSIS

ON INSPECTION:- There is a saucer shaped depression

at or just below the umbilicus- The depression is created by the

dip between the head and the lower limbs of the fetus

- The outline created by the high unengaged head can look like a full bladder

ON PALPATION:- The breech is easily palpated at

the fundus, the back is difficult to palpate as it is adjacent to the maternal spine.

- Limbs can be felt on both side of midline

ON AUSCULTATION:

- The fetal head is not well flexed so the chest is thrust forward, so F.H.S can be heard at midline

- Sometime F.H.S can be heard more easily at the flank on the same side of the back

Mechanism of labourSL.NO NAME

1 Flexion

2 Internal rotation of head

3 Crowning

4 Extension

5 Restitution

6 Internal rotation of shoulder

7 Internal rotation of head

8 Lateral flexion

Criteria:- Lie – longitudinal- Presentation- vertex- Attitude- deflexed head- Denominator- Occiput- Position- ROP, LOP- Presenting part- Middle or

anterior part of left parietal bone

The occipito frontal diameter of 11.5cm lies in the right oblique diameter of pelvic brime. The occiput points to the right sacro iliac joint and sinciput to left ileopectineal eminance

1. Flexion: Decend takes place with increase flexion and occiput is the leading part

2. Internal rotation of head: Occiput reaches the pelvic floor 1st and rotate forward 3/8th of a circle along the right side of pelvis to lie under symphysis pubis. The shoulder follows turning 2/8th of a circle from left to right oblique diameter

Crowning: Occiput escape under the pubic arch and the head is said to be crown

4. Extension: Sinciput face and chin is born by a movement of extension and head is born

5. Restitution: Occiput turns 1/8th of the circle toward the right side and head realign itself with the shoulder.

6. Internal rotation of the shoulder: shoulder enter the pelvis in right oblique diameter , the anterior shoulder reaches the pelvic floor 1st and rotate forward 1/8th of a circle along the left side

7. Lateral flexion – Anterior shoulder escape under the symphysis pubis and posterior shoulder sweap the perineum and the baby is born by a movement of lateral flexion

Early diagnosisCareful monitoring of labourJudicious and timely interference

Watchful expectancy Early caesarean section

Associated complication

- Contracted pelvis

- Post CS pregnancy

- Big baby- Pre-eclampsia

Persistant occipito posterior position

Anterior rotation of occiput(3/8)th

spontaneous

Ventous/ Forcep

Adequate size of pelvis

and fetal status

Mal rotation

Non rotation

Incomplete forward rotation

Occipito sacreal position

Pelvisadequate

Pelvisinadequate

LSCS

Head aboveischeal spine

Head below the levelOf ischeal spine

LSCS/manualRotation and forcep delivery

forcep delivery

Oblique posterior arrest

Deep transversearrest

Baby deathPelvic adequatePelvic inadequate

forcep Ventous delivery

LSCScraniotomy

MECHANISM OF LABOUR IN UNFAVOURABLE CONDITION

In unfavourable condition , the occiput fails to rotate , the cause may be

– deflexion of head

– weak uterine contraction

– faulty shape of pelvis

1. In complete forward rotation i.e in case of mild deflexion of head the occiput rotates 1/8th of a circle anteriorly and the saggital suture comes to lie in bispinous diameter and further anterior rotation is impossible and is called as deep transverse arrest

2. NON ROTATION- Both sinciput and occiput touches the pelvic floor simultaneously due to moderate deflexion of head resulting in non rotation of occiput.this condition is called as oblique posterior arrest

3. MAL ROTATION: In severe deflexion, the sinciput touches the pelvic floor 1st resulting in anterior rotation of sinciput 1/8th of a circle and putting the occiput in the sacreal hallow.This position is term as occipito sacreal position

4. In favourable condition i,e with the average size of baby , good uterine contraction and with adequate pelvis spontaneous delivery may occur as face to pubis delivery. In unfavourable condition when arrest occure it is called as occipito sacreal arrest

Management of OPPPrinciple: strict vigilance with watchful expectancy hoping for descent and

anterior rotation of the occiput Timely diagnosis judicious and timely interference

MANUAL ROTATION:PROCEDURE:-Patient should be place in lithotomy position and general anaesthesia should be given - Strict aseptic technique and catheterize the bladder- Vaginal examination and detect the direction of occiput

Step IGriping the hand: The corresponding hand is

introduce in the vagina in a cone shape manner after separating labia by 2 finger of the other hand.

In occipito transverse position the four finger are push in to the sacreal hollow to be placed over the posterior parietal bone and the thumb is place over the anterior parietal bone

In oblique posterior position the 4th finger of partially supinated are place over the occiput and the thumb is place over the sinciput

STEP IIROTATION OF THE HEAD Attempt is made to make the head flex. The head is to be rotated to

bring the occiput to the anterior side along the shortage route , simultaneously the back of fetus is rotated by the external hand from the flanks to the midline

STEPIIIAPPLICATION OF FORCEP Following the rotation of the head when the right hand is placed on

the left side of pelvis left blade of forcep is to be introduce. When the left hand is used, it is

place on the right side of pelvis after rotation as such the right blade is to be introduce 1st and the left blade is then to be introduce underlying the right blade

Complications

Premature rupture of membranes or its rupture early in labour.

Increased incidence of perinatal mortality.

Cord presentation and prolapse:

A high head predispose to early spontaneous rupture of the membrane, which together with an ill fitting presenting part, may result cord prolapse

Prolonged labour due to hypotonic or hypertonic inertia.

Obstructed labour with higher incidence of rupture uterus.

Increased incidence of instrumental and operative delivery.

Increased incidence of trauma to the genital tract.

Increased incidence of postpartum haemorrhage and puerperal infection

Bibliography- Fraser and Cooper. Myles textbook of midwives.14th

edition.churchill livingstone publication.philadelphia2007. page no 551-557

- Dutta D.C. Text book of obstetrics.6th edition. New central book publication. kolkata 2006. page no 365-374