Malpresentation and malposition

Malpresentation & Malposition

Fetal lie:the relation of fetal long axis to that of the mother, either longitudinal ,transverse or oblique.
Presentation:that portion of the fetal body that is foremost within the birth canal or in close proximity to it.
Position: the relationship of a chosen portion of the presenting part to the right or left sides of the birth canal.

Malpresentation is any presentation other than vertex, which is the commonest presentation.
This includes: breech ,shoulder, face ,brow & compound.

Breech :

Near term, the fetus typically turns spontaneously to a cephalic presentation as the increasing bulk of the buttocks seeks the more spacious fundus.
When fetal buttocks or legs enter the pelvis before the head, the presentation is breech.
It is 3 to 4 % at term


Risk factors:
1.early GA as each fetal pole is of similar bulk earlier in pregnancy.
2.abnormal AFV
3.multifetal gestation
4.hydrocephaly
5.anencephaly
6.uterine anomalies

7.placenta previa

8.fundal placenta
9.pelvic tumors
10.high parity with uterine relaxation
11.prior breech delivery,the recurrence rate for a 2nd pregnancy with breech is 10% & for a 3rd breech is 27%.
12.prior CS increases the incidence two folds.
13.smoking may be a modifiable cause.

Classification:

1.Frank breech:the lower extremities are flexed at the hips & extended at the knees , thus the feet lie in close proximity to the head.
2.Complete breech:one or both knees are flexed.
3.Incomplete breech:one or both hips are not flexed & one or both feet or knees lie below the breech.
4.Footling:is an incomplete breech with with one or both feet below the breech.


In 5% of term breech fetuses, the head may be in extreme hyperextension , this called stargazer fetus & in Britain flying fetus.
With such hyperextension , vaginal delivery may result in injury to the cervical spinal cord.
Thus if present it is indication for CS.

Dx.:

Risk factors
Exam.:
The hard,round ,ballottable fetal head found occupying the fundus & the firm breech in the pelvis.
With suspected breech or any presentation other than cephalic, US is indicated.

The fetal sacrum & its spinous processes are palpated to establish position.

Fetal positions are designated as left sacrum anterior(LSA),right sacrum anterior(RSA), left sacrum posterior(LSP), right sacrum posterior (RSP), or sacrum transverse (ST) to reflect the relations of the fetal sacrum to the maternal pelvis.

Route of delivery:

This is determined by multiple factors:
1.fetal characteristics
2.pelvic dimensions
3.coexistent pregnancy complications
4.operator experience
5.patient preference
6.hospital capabilities


Factors favoring C delivery:
1.lack of operator experience
2.patient request for CS
3.large fetus >3800 to 4000 g
4.apparently healthy & viable preterm fetus either with active labor or with indicated delivery
5.sever fetal growth restriction
6.fetal anomaly incompatible with vaginal delivery

7.prior perinatal death or neonatal birth trauma

8.incomplete or footling breech
9.hyperextended head
10.pelvic contraction or unfavorable pelvic shape determined clinically or with pelvimetry
11.prior CS

There are 3 methods of vaginal breech delivery:

1.spontaneous breech delivery,the fetus is expelled entirely spontaneously without any traction or manipulation other than support of the newborn.
2.partial breech extraction,the fetus is delivered spontaneously as far as the umbilicus but the remainder of the body is extracted or delivered with operator traction & assisted maneuvers.

3.Total breech extraction,the entire body of the fetus is extracted by the obstetrician

Induction or augmentation of labor in women with a breech is controversial.


Management of labor:
1.assessement of the status of membranes, labor, & fetal condition.
2.surveillance of fetal heart & uterine cont.
3.staff should include; an obstetrician skilled in the art of breech extraction, an associate to assist with delivery,anesthetic who can ensure adequate analgesia or anesthesia when needed,an individual trained in newborn resuscitation.

4.engagement & descent of breech takes place with the bitrochanteric diameter.

5.mechanism of labor:the ant.hip descends more rapidly than the post.hip & when the resistance of the pelvic floor is met , internal rotation of 45 degrees follows bringing yhe ant.hip toward the pubic arch & allowing the bitroch. Diam. To occupy the AP diam.Of the pelvic outlet.

After rotation,descent continues & the ant hip appears at the vulva. By lat flexion the post hip is forced over the perineum .
The legs & feet follow the breech .
After breech birth,there is slight external rotation, with the back turning ant , the shoulders then descend & undergo internal rotation with the bisacromial diameter occupying the AP plane.

Immediately following the shoulders, the head enters the pelvis in one of the oblique diameters & then rotates to bring the post portion of the neck under symph pubis, the head is then born in flexion.

6.with all breech deliveries,an episiotomy is made.

7.delivery is allowed sponta to the umbilicus then the abd ,thorax ,arms & head must be delivered promptly either spont or assisted.
8.following delivery of the legs,the fetal bony pelvis is grasped with both hands using a towel.The fingers rest on the AS iliac crests & thumbs on the sacrum.

9.gentle downward traction until lower halves of scapulas are delivered,then the fetal back tends to turn spont towards the side of the mother .
10.two methods for shoulder delivery;in the 1st with the scapula visible the trunk is rotated so that the ant shoulder & arm appear at the vulva & can be released & delivered first.The body of fetus is then rotated 180 degrees in the reverse direction to deliver the other shoulder & arm.


The 2nd method is employed if trunk rotation is unsuccessful,with this maneuver the post shoulder is delivered first.
11.after both shoulders delivery,the back of the fetus rotates in the direction of symphysis.
12.delivery of aftercoming head:
Mauriceu Maneuver:the index & middle finger of one hand are applied over the maxilla to flex the head while the body rests on the palm of the hand & forearm.

Two fingers of the other hand are hooked over the fetal neck grasping the shoulders , downward traction is applied until suboccipital region appears .
The body then is elevated toward the maternal abd & the mouth , nose ,brow, & eventually the occiput emerge over the perineum.

Version:

With this procedure , fetal presentation is altered by physical manipulation either substituting one pole of a longitudinal presentation for the other , or converting an oblique or transverse lie into a longitudinal lie.
According to whether the or breech is made the presenting part , the operation is designated cephalic or podalic version.

With external version , the manipulation are performed exclusively through the abdominal wall.
With internal version ,they are accomplished inside the uterine cavity.

ECV:

It is done before labor after 36 weeks , before this time there is still a high likelihood of correcting spontaneously, & if performed too early time may allow a return back to breech.

CI:version is CI if vaginal delivery is not an option ex.:

1.placenta previa
2.nonreassuring fetal status
3.rupture of membranes
4.uterinr malformations
5.multiple gestation
6.recent uterine bleeding
7. prior uterine incision is a relative CI

Factors improving the chances for successful version:

1.multiparity
2.abundant AF
3.unengaged presenting part
4.fetal size 2500 to 3000 g
5.posterior placenta
6.nonobese patient

Complications:

1.projected success rates
2.conversion back to breech
3.placental abruption
4.uterine rupture
5.fetomaternal hemorrhage
6.alloimmunization
7.preterm labor
8.fetal compromise & even death
9.emergency CS


Technique:
1.tocolytic agents given such as terbutaline , ritodrine,sulbutamol nifedipine,nitroglycerin.
2.analgesics
3.facilities for an emergency CS
4.US performed to confirm presentation,AFV,
Exclude fetal anomalies & placental location.
5.FHR monitoring
6.Anti-D to Rh-D negative

Each hand grasps one fetal pole,the buttocks elevated from the maternal pelvis, the buttocks are guided gently towards the fundus & the head towards the pelvis.

Version attempts are discontinued if:

1.excessive discomfort
2.persistently abnormal FHR
3.multiple failed attempts

Internal podalic version:

Used only for delivery of 2nd twin.
Membranes preferably intact.
A hand inserted into the uterine cavity to turn the fetus manually.
One or both feet drawn through the cervix , while the other hand transabdominally pushing the upper portion of fetal body.
This is followed by breech extraction.


Face presentation:
The head is hyperextended so that the occiput is in contact with the fetal back & the chin (mentum)is presenting.
It may present with chin ant. Or post. Relative to the maternal symphysis pubis.

Etiology:

1.conditions that prevent head flexion as a neck mass
2.preterm infants
3.coils of cord around the neck
4.hydramnios
5.fetal anomalies as anencephaly
6.contracted pelvis & large fetus
7.high parity

Dx.:

By vaginal examination, palpation of facial features
Breech may be mistaken for face because anus mistaken for mouth & ischial tuberosities for malar prominences.
US shows hyperextended head & facial bones below pelvic inlet


Mx.:
Successful vaginal delivery can occur in mentoanterior.
Most mentopost. Convert to ant. In labor,if not the fetal brow(bregma) is pressed against the maternal sym.pubis
This precludes head flexion,thus mentopost. Is undeliverable vaginally.

Mechanism of labor includes descent,internal rotation,flexion & accesory movements for extension & external rotation.
Edema may sometimes distort the face & skull undergoes molding.

Brow :

The portion of the head between the orbital ridge & the ant. Fontanel presents at the pelvic inlet, so the fetal head occupies a position midway between full flexion (occiput) & extension (face).
Causes are the same for brow.

Dx.:

By abd. Palpation both occiput & chin can be palpated easily.
The frontal sutures , large ant. Fontanel , orbital ridges , eyes , & root of nose are felt on vaginal exam. , but neither the mouth nor the chin is palpable.

Labor:

A brow presentation is commonly unstable & often converts to face or occiput.
If the brow persists, prognosis is poor for vaginal delivery this is because engagement is impossible until there is marked molding & this will deform the head.

Transverse lie:

The long axis of the fetus is perpendicular to that of the mother.
Here the shoulder is positioned over the pelvic inlet ,shoulder presentation.
Causes:high parity,preterm,PP , uterine abn., hydramnios , contracted pelvis.


Dx.:
By inspection, the abd. Is unusually wide where as the fundus is only slightly above the umbilicus.
No fetal pole is detected in the fundus & the ballottable head is found in one iliac fossa & the breech in the other.

The back position is identified, with back ant. , a hard resistance plane extends across the front of the abd. ,when it is post. , irregular nodulations representing fetal small parts are felt.
On vaginal exam., scapula & clavicle can be felt.

Mx.:

It is an indication for CS.
If labor starts with a neglected transverse lie, the uterus will rupture.
With CS, a low transverse uterine incision may lead to difficult fetal extraction therefore a vertical incision is indicated.

Compound presentation:

An extremity prolapses alongside the presenting part such as a hand or arm with the head.
Causes : are conditions that prevent complete occlusion of the pelvic inlet by the fetal head including preterm labor.

Mx.:

The condition should be observed closely to ascertain whether the arm retracts with descent of the presenting part.
If it fails to retract & prevents descent of the head,it should be pushed gently upward & the head downward by fundal pressure.

Malposition:

Occiput post.:20% of labors, it is assoc. with a narrow forepelvis & ant. Placentation.
Mechanism of labor is same as occiput ant. Except that the occiput has to internally rotate to the symphysis pubis through 135 degrees instead of 90 & 45 degrees respectively.


Effective contractions, adequate head flexion & average fetal size permit most post. Positions to rotate promptly.
Poor contr. ,faulty head flexion or epidural analgesia may predispose to incomplete rotation.
If no rotation takes place the occiput remains in direct OPP known as persistent OP.

POPP:

2 to 10% of singleton term cephalic fetuses deliver in OPP.
Women with POPP have higher rates of prolonged 2nd stage, CS,operative vaginal delivery, increased blood loss & 3rd &4th degree lacerations.

Infants delivered from an OPP have more complications than those born from OAP.

Every possible compl. Was found more frequently with POOP, such as birth trauma, low Apgar score, intensive care unit admission.

Delivery of POOP is by spontaneous or operative vaginal delivery.

If neither can be completed with relative ease, CS is performed.

Occiput transverse position:

This is usually transitory , it will rotate to OA.
If no rotation,vaginal delivery can be accomplished in a number of ways:
1.manual rotation to OA or OP.
2.rotation with Kielland forceps
3.CS