Malposition and Malpresentation

pregnancy

Malposition and Malpresentation

As pregnancy progresses, it becomes important to determine the presentation and position of the fetus in relation to the mother pelvis. In approximately 95% of the birth, the fetal head presents first.

Occipitoposterior position

  • A cephalic presentation of the fetus with its occiput turned toward the sacrum or rotated to the right (right occipitoposterior, ROP) or to the left (left occipitoposterior, LOP) sacroiliac joint of the mother.
  • Most common of malposition of the occiput and occur in approximately 10% of labour.

Causes

  • The direct cause is often unknown, but it may be associated with an abnormally shaped pelvis. In android pelvis the forepelvis is narrow and the occiput tend to occupy the roomier hindpelvis.
  • The oval shape of the anthropoid pelvis, with its narrow transverse diameter, favours a direct occipitoposterior position.

Diagnosis

  • The woman may complain of continuous and sever backache worsening with contraction. The absence of backache doesn’t necessarily indicate an anteriorly-positioned fetus.
  • The large and irregularly shaped presenting circumference doesn’t fit well onto the cervix. Therefore the membranes tend to rupture spontaneously at an early stage of labour and contraction may be incoordinate. Descent of the head can be slow even with good contraction. The woman may have a strong desire to push early in labour because the occiput is presenting on the rectum.

Management

Labour with a fetus in an occipitoposterior position can be long and painful. The deflexed head doesn’t fit well onto the cervix and therefore doesn’t produce optimum stimulation for uterine contractions.

First stage of labour

  • The woman may experience sever and unremitting backache which is tiring and can be very demoralising especially if the progress of labour is slow. Continuous support from the nurse will help the mother and her partner to cope with the labour.
  • The nurse can help to provide physical support such as message and other comfort measure and suggest changes of posture and position.
  • The woman may experience a strong urge to push long before her cervix has become fully dilated. This is due to the pressure of the occiput on the rectum. If the woman pushes at this time, the cervix will become edematous and this would delay the onset of the second stage of labour.
  • The urge to push may be eased or controlled by a change in position and the use of breathing technique or entonox to enhance relaxation.

Second stage of labour

  • Full dilation of the cervix may need to be confirmed by a vaginal examination because moulding and formation of the caput succedaneum may bring the vertex into view while an anterior lip of cervix remains. If the head is not visible at the onset of the second stage, then the nurse could encourage the woman to remain upright.
  • This position may shorten the length of the second stage and may reduce the need for operative delivery. In some cases where contractions are weak and ineffective Syntocinon infusion may be commenced to stimulate adequate contractions and achieve advance. As with any labour the maternal and fetal conditions are closely observed throughout the second stage.
  • The length of the second stage of labour is increased when the occiput is posterior an there is an increased likelihood of operative delivery.

Complication associated with occipitoposterior position:

  • Obstructed labour.
  • Maternal trauma
  • Neonatal trauma
  • Cord Prolapse.
  • Cerebral Hemorrhage

Face presentation

In a face presentation, the fetal head and neck are hyperextended, causing the occiput to come in contact with the upper back of the fetus while lying in a longitudinal axis. The presenting portion of the fetus is the fetal face between the orbital ridges and the chin. The fetal chin (mentum) is the point designated for reference during a vaginal examination. The mentum can present in any position relative to the maternal pelvis. If the mentum presents in the left anterior quadrant of the maternal pelvis, it is designated as left mentum anterior (LMA).

Causes

Anterior obliquity of uterus

The uterus of a multiparous woman with slack abdominal muscles and a pendulous will lean forward and alter the direction of uterine axis. This causes the fetal buttocks to lean forwards and the force of the contraction to be directed in a line towards the chin rather than the occiput resulting in extension of the head.

Contracted pelvis

In the flat pelvis, the head enters in transverse diameter of the brim and the parietal eminences may be held up in the obstetrical conjugates; the head becomes extended and a face presentation develops.

Alternatively, if the head is in the posterior position, vertex presenting, and remains deflexed, the parietal eminences may be caught in the sacrocotyloid dimensions, the occiput doesn’t descend, the head becomes extended and face presentation result. This is more likely in the presence of an android pelvis in which the sacrocotyloid dimension in reduced.

Polyhydromnios

If the vertex is presenting and the membranes rupture spontaneously, the resulting rush of fluid may cause the head to extend as it sinks into the lower uterine segment.

Congenital abnormality

Anencephaly can be a fetal cause of a face presentation. In a cephalic presentation, because the vertex is absent, the face is thrust forward and presents. More rarely a tumour of the fetal neck may cause extension of the head.

Labor Management

  • Continuous fetal heart rate monitoring is considered mandatory because of the increased incidence of abnormal fetal heart rate patterns and/or fetal compromise.
  • Forceps may be used if the mentum is anterior.
  • During delivery, careful attention must be taken to avoid hyperextension of the fetal head.
  • Administer of oxytocin.
  • Perform cesarean delivery when arrest of labor occurs.

Complications

  • Obstructed labour
  • Cord Prolapse
  • facial bruising
  • Cerebral hemorrhage
  • Maternal trauma

Brow Presentation

In a brow presentation, the fetal head is partially extended with the frontal bone, which is bounded by the anterior fontanelle and the orbital ridges, lying at the pelvic brim. This presentation is rare, with an incidence of approximately 1 in 1000 deliveries.

Causes

During the process if extension from a vertex presentation to a face presentation, the brow will present temporarily and in a few cases this with persist.

Labor Management

  • Cesarean section required in most cases
  • Brow presentation rarely can deliver vaginally unless:
  • Spontaneously converts to vertex or face presentation.
  • Fetus is very small or pelvis is very large
  • Do not attempt to convert brow presentation to vertex.
  • Never apply vacuum extractor to brow presentation.
  • Do not apply internal scalp electrodes.
  • Avoid oxytocin

Breech presentation

Breech presentation is defined as a fetus in a longitudinal lie with the buttocks or feet closest to the cervix. This occurs in 3-4% of all deliveries. The percentage of breech deliveries decreases with advancing gestational age from 22% of births prior to 28 weeks’ gestation to 7% of births at 32 weeks’ gestation to 1-3% of births at term.

Categories

There are four main categories of breech births:

  • Frank breech – the baby’s bottom comes first, and his or her legs are flexed at the hip and extended at the knees (with feet near the ears). 65-70% of breech babies are in the frank breech position.

Complete breech – the baby’s hips and knees are flexed so that the baby is sitting crosslegged, with feet beside the bottom.

  • Footling breech – one or both feet come first, with the bottom at a higher position. This is rare at term but relatively common with premature fetuses.
  • Kneeling breech – the baby is in a kneeling position, with one or both legs extended at the hips and flexed at the knees. This is extremely rare.

Etiology

  • multiple (or multifetal ) pregnancy (twins, triplets or more)
  • abnormal volume of amniotic fluid: both Polyhydromnios and oligohydramnios
  • fetal anomalies: hydrocephaly, anencephaly and other congenital abnormalities
  • uterine abnormalities
  • prior Cesarean section

Management

  1. Ultrasound exam, to better check the position of the baby, the location of the placenta, and the amount of amniotic fluid in the uterus.
  2. Gentle pushing on the lower abdomen can turn the baby into the head-down position.
  3. Check the fetal heart rate.
  4. An epidural block may used to inhibit the urge to push prematurely.

Types of delivery

  1. Spontaneous breech delivery
  2. Assisted breech delivery
  3. Total breech extraction
  4. Forceps delivery
  5. Caesarean section

Complications

  1. Impacted breech
  2. Cord Prolapse
  3. Birth injury
  4. Fetal hypoxia
  5. Premature separation of the placenta
  6. Maternal trauma

Shoulder presentation

When the fetus lies with its long axis across the long axis of the uterus (transverse lie) the shoulder is most likely to present. Occasionally the lie is oblique but this doesn’t persist at the uterine contraction during labour make it longitudinal or transverse.

Shoulder presentation occurs in approximately 1: 300 pregnancies near term. Only 17% of these cases remain as a transverse lie at the onset of labour.

Causes

Maternal

  • Lax abdominal and uterine muscles
  • Uterine abnormality
  • Contracted pelvis

Fetal

  • Preterm pregnancy
  • Multiple pregnancies
  • Polyhydromnios
  • Macerated fetus
  • Placenta praevia

 

Management

Antenatal

A cause must be sought before deciding on a course of management. Ultrasound examination can detect placenta praevia or uterine abnormalities, whilst x-ray pelvimetry will demonstrate a contracted pelvis. Any of these causes requires elective caesarean suction. Once they have been excluded, external version may be attempted. If this fails, or if the lie is sign transverse at the next antenatal visit, the woman is admitted to hospital while further investigations into the cause are made.

Intrapartum

If the transverse lie is detected in early labour while the membranes are still intact, the doctor may attempt an external version followed, if this is successful, by controlled rupture of the membranes. If the membranes have already ruptured spontaneously, a vaginal examination must be performed immediately to detect possible cord prolapse.

Immediate caesarean auction must be performed:

  • If the cord prolapse
  • When the membranes are already ruptured
  • When external version is unsuccessful
  • When labour has already been in progress for some hours.

Complications

  • Prolapsed cord
  • Prolapsed arm
  • Neglected shoulder presentation

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