Face presentation in pregnancy.

Ekai kaoo By Ekai kaoo, 2nd Aug 2013 | Follow this author | RSS Feed
Posted in Wikinut>Health>General Health>Fertility & Reproductive Health

face presentation is one of the malpresentation that occur during pregnancy.

positions in face presentation.

Face Presentation

Face presentation occurs when the head has complete extension, and the occiput is in contact with its spine. It happens in about one in every five hundred labour. Primary face presentation is when the face presents before labour. The term secondary face presentation is used when the face presents during labour. There are six positions in a face presentation, namely:
• Right mento-posterior
• Left mento-posterior
• Right mento-lateral
• Left mento-lateral
• Right mento-anterior
• Left mento-anterior
The denominator is the mento, the presenting diameters are the submento bregmatic (9.5cm) and the bi-temporal (8.2cm).

Causes of Face Presentation
You will now look at some of the causes of face presentation in detail.

Anterior Obliquity of the Uterus
The pendulous abdomen of a multiparous woman leans forward resulting in the alteration of the direction of the uterine axis. This causes the foetal buttocks to also lean forward and the force of the contractions to be directed in a line towards the chin, rather than occiput, which usually results in extension of the head.

Contracted Pelvis
Face presentation develops as the head enters in the transverse diameter of the brim. The obstetric conjugate is bound to be withheld which will result in the extended head in an android pelvis. Face presentation results when vertex presentation is in the posterior position and remains deflexed. The parietal eminences are caught in the reduced sacro-cotyloid dimension, the occiput does not descend and the head becomes extended.

In polyhydramnios, when the spontaneous rupture of membranes occurs, the resulting rush of fluids may cause the head to extend as it sinks into the loweruterine segment.

Congenital Abnormality
The absence of vertex in the encephally thrusts the face forwards. A tumour on the foetal neck can also cause extension of the head although this is rare.

Abdominal and Per Vaginal Diagnosis of a Face Presentation
The diagnosis is usually made in labour. During an abdominal examination check for the following features:
• The shape of the foetal spine is an s-shape.
• The round occiput is prominent and may be ballottable when the position is mento-posterior and a deep groove can be felt between it and the back.
The diagnosis is not always easy and clear. During a vaginal examination you may notice that you can diagnose face presentation with confidence if you have mastered vaginal examination skills. You will differentiate face from brow presentation when you feel the orbital ridges, the brow itself and the anterior sutures. You should look for the following characteristics:
• The presenting part is usually high, soft and irregular
• In a sufficiently dilated cervix you may feel orbital ridges, eyes, nose and mouth
• The mouth may be open with hard gums
• The foetus may suck the examining finger
• In progressive labour, the face becomes oedematous and is difficult to distinguish it from a breech presentation
• To determine the mentum, you must locate it, and if it is posterior, you should decide whether it is lower than the sinciput in order to rotate forward
and advance
• The orbit ridges determine the position either on the left or right oblique of the pelvis brim
Mechanism of Left Mento-Anterior Position
In face presentation, you will be substituting occiput with the chin. Instead of flexion you will maintain deflexion and instead of extension you will maintain flexion. Now look at the secret formula:
• Lie is longitudinal
• Attitude is one of extension of the head and the back
• The presentation is face
• The position is left mento anterior. In a left mento anterior position the orbital ridges will be in the left oblique diameter of the pelvis
• The denominator is the mentum
• The presenting part is the left molar bone

Descent takes place throughout and with increasing extension and thus the mentum becomes the leading part

Internal Rotation of the Head
This occurs when the chin reaches the pelvis floor and rotates forwards 1/8 of a circle. The chin escapes under the symphysis pubis. When this takes place and the sinciput, vertex and occiput sweep the perineum, the head is born.

This occurs when the chin turns 1/8 of a circle to the mother’s left.

Internal Rotation of Shoulders
The shoulders enter the pelvis in the left oblique diameter and the anterior shoulder reaches the pelvis floor first and rotates forward 1/8 of a circle along the right side of
the pelvis.

External Rotation of the Head
This occurs simultaneously and the chin moves a further 1/8 of a circle to the left.

Lateral Flexion
The anterior shoulder escapes under the symphysis pubis, the posterior shoulder sweeps the perineum and the body is born by a movement of lateral flexion.

Prolonged Labour
Labour is often prolonged due to ineffective uterine contraction caused by an ill-fitting presenting part. The facial bones do not mould and in order to enable the mentum reach the pelvic floor and rotate forwards, the shoulders must enter the pelvic cavity at the same time as the head.
With good uterine contractions, descent and rotation of the head occurs and labour progresses through to a spontaneous delivery.

Mento-Posterior Position
When the head is completely extended with an effective contraction, the mentum reaches the pelvic floor first and will rotate forwards an the position becomes anterior.

Persistent Mento-Posterior Position
The head is incompletely extended, the sinciput reaches the pelvic floor first and rotates forwards 1/8 of a circle, which brings the chin into the hollow of the sacrum. Further mechanism is prohibited, which results in impacted face. In order for further descent, both head and chest have to be accommodated in the pelvis.

Management of Labour in Face Presentation
Upon diagnosing the condition the first action you must take is to inform the doctor about the face presentation. Routine maternal and foetal condition observations are done as in normal labour (maternal pulse, foetal heart rate and contraction) half hourly. Blood pressure and temperature is done two hourly. Empty the urinary bladder every two hours.
Vaginal examination to determine cervical dilation and descent of the head, is done every four hours to monitor progress of labour. Take care not to injure the foetal eyes. In mento-posterior positions, the midwife should note whether the mentum is lower than the sinciput since rotation and descent depends on this. If the head remains high despite good uterine contractions, the mother is prepared for caesarean section.

Management of Labour in Face Presentation
Face extends to the Perineum
When the face extends to the perineum, give episiotomy to prevent extensive perineum tear.

Face appears at the Vulva
When the face appears at the vulva, maintain extension by holding back the sinciput until the chin is delivered.

Chin has been delivered
Once the chin has been delivered allow the occiput to sweep the perineum. In this way the submento-vertical diameter (11.5cm) distends the vaginal orifice, instead of the mento vertical diameter (13.5cm).

Occiput rides over Perineum

Head is flexed completely
The head is flexed completely and it is delivered.
Inform the doctor if the head does not descend in the second stage. In a mento-anterior position, it may be possible to deliver the baby using forceps.
If the head becomes impacted, or there is any suspicion of disproportion, a caesarean section will be necessary.

There are several possible complications during labour with a face presentation.

Obstructed Labour
A minor degree of contracted pelvis may result in obstructed labour as facial bones do not mould. Caesarean section is necessary in persistent mento posterior position.

Cord Prolapse
A prolapsed cord is more common when the membranes rupture because the face is an ill-fitting presenting part. Always perform a vaginal examination following rupture of membranes to rule out cord prolapse.

Facial Bruising
The baby’s head is elongated with a swollen bruised
face, oedematous eyelids and lips at birth. You should take great care while performing vaginal examination to avoid injury.

Cerebral Haemorrhage
The lack of moulding of facial bones can lead to intra-cranial haemorrhage caused by excessive compression
of the foetal skull or by upward compression in the
typical moulding of the foetal skull found in this type
of presentation.

Maternal Trauma
Extensive perineal laceration may occur at delivery due to the large submento vertical and bi-parental diameters distending the vagina and perineum. This increases the incidence of caesarean section, which can increase chances of maternal morbidity and mortality.



Meet the author

author avatar Ekai kaoo
Am a fourth year student undertaking Bachelor of science in Nursing.I like writing articles of medical field.

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