malposition

Malposition

Occipitoposterior position 18


Fetal malpositionThis refers to the relationship between the denominator &the pelvis that make spontaneous delivery unfavourable,e.g.occipito-posterior in vertex presentation,sacro-posterior in breech presentation&mento-posterior with face presentation.
osition


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presentation

The lowest pole of the fetus that presents to the lower uterine segment &cervix Denominator Is the most definable peripheral point in the presenting part Position The relationship of the denominator of the of the presenting part to fixed point of the maternal pelvis If the occiput lies in the posterior half of the pelvis,then it is considered malposition&usually present with a slightly extended head.

aetiology

The head enters the pelvic brim with occipitolateral position then rotate to occipito-anterior in 80% When the head not well flexed ,the diameter of the persenting part will be larger and increases as the deflection increased until reaching face presentation when submento-pregmatic is9.5 cm



aetiology
In normal labor the contraction force the head to flex &rotate ;if deflection persist ,the bregma reaches the pelvic floor first &rotate anteriorly cause occiput posterior(op) In epidural anasthesia there is laxity in pelvic muscle leading to op In andriod pelvis there is less space anteriorly that cannot be occupied by occiput

Synclitisim:-the parietal eminences are at the same level in the pelvis. Asynclitism:-when the saggital suture shifted more anterior or posterior Anterior asynclitism:-parietal eminence in the anterior 1/2of the pelvis &lower Posterior asynclitism:-parietal eminence in the posterior 1/2of the pelvis&lower

Anterior asynclitism Naegele's obliquity

Normal synclitism
Posterior asynclitism Litzmann's obliquity Ear presentation

Occipitoposterior position

occurs when the fetal occiput is posterior in relation to the maternal pelvis

Occiput anterior

Right Occipitoposterior

Left Occipitoposterior

Left Occipitoposterior

Left Occipitoposterior

Right Occipitoanterior

Left Occipitoanterior

Mechanism of labour in Occipitoposterior position:

ROP is more common than the LOP Mechanism of labour depends whether the head is well flexed or not

The well flexed head

The occiput slides down the gutter formed by the levator muscles, undergoing long rotation through three-eighths of the circle, and reach the free space under the pubic arch With ROP the head will rotates along the right side of the pelvis to the front, and the shoulders will rotate with the head from the left oblique diameter into the anteroposterior diameter. After rotation the mechanism is same as ROA and the head delivered by extension



The incompletely flexed head
The larger occipitofrontal diameter, which measure 11.5 cm, pass through the pelvis instead of the suboccipitobregmatic diameter , which measure 9.5 cm The forehead is as low as the occiput, meets the pelvic floor before the occiput, and rotates to the free space under the pubic arch, turning through the one-eighths of the circle, while the occiput rotates backwards under the hollow of the sacrum. Head born with face to pubis, the vertex born by flexion followed by the occiput

Left Occipitoposterior

Deep transverse arrest of the head
The head arrest with its long axis in the transverse diameter of the pelvis The head extended that neither the occiput nor the forehead meet the pelvic floor and enhance rotation Some cases are due to incomplete forward rotation from an Occipitoposterior position The majority are the result of descent of the head originally in an occipitotransverse position and failed to rotate anteriorly

Right occiput transverse

Left occiput transverse

Summery

summery In most cases normal vaginal delivery occurs, where a well flexed head under go long rotation of about 3/8 of the circle and lie under the pubic arch ( suboccipitobregmatic diameter = 9.5 cm) In 20% the malposition persist, where a poorly flexed head fail to under go long rotation and rotate only 1/8 of the circle and delivered face to pubis ( occipitofrontal diameter = 11.5 cm )



Diagnosis
Diagnosis during pregnancy is of no importance except that the head is not engaged During labour early rupture of the membrane indicate OP

Abdominal examination:

Slight flattening of the lower abdomen The limbs are easily felt Difficult to define the back Difficult to hear the fetal heart Slow descend of the head during contraction occur if the head is poorly flexed

Vaginal examination

Early in labour difficult to reach the presenting part and the membranes may rupturedLater on the fontanelle is feltWell flexed head → posterior fontanelle Less poorly flexed head → anterior and posterior fontanellePoorly flexed head → anterior fontanelleDelay in the second stage of the labour with the formation of caput succedaneumMoulding of the head

Course of labour

80% spontaneous rotation to occiput anterior 10% short rotation and delivery face to pubis Remainder assisted rotation is required Uterine contraction is ineffective Prolonged first stage Prolonged second stage

Management of first stage of labour:

Nothing than the normal labour with follow up of labour by a partogram If progressive cervical dilatation is not occur, augmentation of uterine contraction by syntocinon drip is done Cesarean section indicated if there is poor progress of labour or if there is fetal distress

Management of second stage of labour

A desire to bear down before the cervix is being fully dilated has occur lead to false diagnosis of the second stage of labour Examination of the fontanelle to assist the degree of flexion Caput succedaneum and moulding suggest poor rotation of the head if delivered face to pubes, perineal tear occur



indication for interference: failure of descend of presenting part fetal distress maternal distress

assistant delivery to enhance rotation of the head by:

Manual rotation and forceps delivery
epidural anesthesia, pudendal block, or general anesthesia is required if ROP, rotation of the head with fingers along the right side of the pelvis if LOP, rotation of the head with the fingers along the left side of the pelvis shoulder girdle of the fetus should be rotated at the same time by applying pressure on the abdomen using the other hand forceps applied after rotation of the head to occiput anterior

Vacuum extractor

Types of vacuum: 1.Rigid vaccum: O’neil Bird Malmstrom

2.Soft vacuum: Funnel cause less fetal injury ,higher failure rate .mushroom Ring


Check the application. Ensure there is no maternal soft tissue (cervix or vagina) within the rim

FAILURE

If vacuum extraction fails perform caesarean section

Arrest at the pelvic outlet

It is occurred when the head is so low in the pelvic cavity that is easy visible with each uterine contraction but arrest Episiotomy is performed and delivery assisted with either obstetrical forceps or vacuum that allow traction alone with out the need for rotation

Trial of forceps with an Occipitoposterior position

Some times it is difficult to obtain rotation of the head from OP to OA, so trial of forceps in the theatre and every thing is ready for cesarean section

FAILURE

Forceps failed if: fetal head does not advance with each pull; fetus is undelivered after three pulls with no descent or after 30 minutes. Every application should be considered a trial of forceps. Do not persist if there is no descent with every pull. If forceps delivery fails, perform a caesarean section.

Deep transverse arrest of the head

The head descend to the level of the ischial spine and the sagital suture lies in the transverse diameter of the head The head is poorly flexed The condition only diagnosed during the second stage of labour If the head is firmly fixed, obstructed labour will result Correction by rotation and extraction in the same way as in Occipitoposterior position

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