ABNORMAL PRESENTATIONS AND MALPOSITIONS Professor, MSc, Dr. Consultant in O & G. Wilfredo Garcia Novoa

In the third trimester of pregnancy physical exam can help us to define the lie, presentation, and position of the fetus. Lie refers to the long axis of the fetus in relation to the long axis of the uterus. Presentation is that part of the fetus which is at the pelvic brim, in other words the part of the fetus presenting to the pelvic inlet. Position refers to the way in which the presenting part is positioned in relation to the maternal pelvis. Strictly speaking this refers to any presenting part, but here it will be considered in relation to those fetuses presenting head first (cephalic).

Malposition Malposition is when the head, coming vertex first, does not rotate to occipitoanterior, presenting instead as persistent occipitotransverse or occipitoposterior.

Malposition: With malposition, the first and the second stage of labour are usually longer Occipitoposterior position could have a vaginal delivery with the head coming out “face to pubis”, or after manual rotation, rotational ventouse or rotational forceps delivery. Caesarean section could be required

Malpresentation Normal presentation is vertex of the fetal head and the word Malpresentation describes any nonvertex presentation. This may be of the face, brow, compound, breech or some other part of the body if the lie is oblique or transverse.

Malpresentations: Face presentation: This occurs in about 1:500 births. Usually only recognized after the onset of labour, easy to confuse with a breech. The position of the face is described with reference to the chin, using the prefix mento. Due to complete extension of the fetal head. The presenting diameter is as submento-bregmatic (9,5cm). Progress in labour is slow. Diagnosis by palpating the nose, mouth and eyes on vaginal examination. In Mento-anterior position vaginal delivery is possible In Mento-posterior position vaginal delivery is impossible= Caesarean Section.

Malpresentations: Brow presentation: It can be considered a mid-way position between vertex and face. Occurs in approximately 1:2000 births. The presenting diameter is Occipito-mental diameter (13-13,5cm). It diagnosed in labour by palpating the anterior fontanelle, supra-orbital ridges and nose on vaginal examination. This is incompatible with a vaginal delivery = Caesarean Section.

Shoulder presentation: Malpresentations: Shoulder presentation: Occur 1 in 300 deliveries. Result of a transverse or oblique lie of the fetus. This is incompatible with a vaginal delivery = Caesarean Section.

Malpresentations: Breech presentation: The incidence is around 25% at 32 weeks and only 3% at term. The chance of breech presentation turning spontaneously after 38 weeks is less than 4%. Is associated with multiple pregnancy, bicornuate uterus, fibroids, placenta praevia, polyhydramnios and oligohydramnios.

Breech presentation: Could be: - Extended or Frank breech - Flexed or Complete breech - Footling breech.

Principle complications of breech delivery: Prolapse of the cord Difficulty in delivering the shoulders (possible damage to the brachial plexus to the fetus or to the liver) Difficulty in delivering the head. (possible intracranial bleeding, prolonged compression of the umbilical cord and asphyxia)

No intent vaginal delivery if: Baby is footling presentation. The predicted weight is less than 1,5 kg or greater than 3,5 kg, or if the maternal pelvis is narrow in any dimension.

Management of breech delivery: Should be attend in a hospital with surgical unit. In early rupture of membranes cord prolapse should be rule out. Slow progress could be associated with sacrum-posterior position or big baby. No ARM until advanced dilatation Continuous assess of fetal wellbeing Epidural analgesia could be use

Management of breech delivery: The team should be ready for the delivery Oxytocin infusion and forceps delivery, if is necessary Empty the bladder Episiotomy Spontaneous evolution, no touch the fetus until the scapula are out A small loop of cord may be pulled down and cardiac pulsations felt. Loveset’s manoeuvre for delivery the shoulders if is necessary Bracht manoeuvre. Mauriceau- Smellie-Viet manoeuvre. Forceps delivery

Management of breech delivery: Caesarean Section: At least 30% of babies presenting by breech are now delivered by elective caesarean section, because of possible long-term damage, which can result from vaginal birth.

SUMMARY DEFINITIONS ( LIE, PRESENTATION AND POSITION) MALPOSITIONS MALPRESENTATIONS (BROW, FACE, SHOULDER AND BREECH) BREECH PRESENTATION

BIBIOGRAPHY CURRENT BOCK TEN TEACHER INTERNET REVISIONS

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