Face Presentation
Definition:
It is a cephalic presentation in which the head is completely extended.
Incidence: About 1:300 labours.
Aetiology :
(A) Primary face:
-It is less common.
– occurs during pregnancy.
-It is usually due to foetal causes which may be:
1. Anencephaly: due to absence of the bony vault of the skull and the scalp while the facial portion is normal.
2. Loops of the cord around the neck.
3. Tumours of the foetal neck e.g. congenital goitre.
4. Hypertonicity of the extensor muscles of the neck.
5. Dolicocephaly: long anteroposterior diameter of the head, so as the breadth is less than 4/5 of the length.
6. Dead or premature foetus.
7. Idiopathic.
(B) Secondary face:
– It is more common.
– occurs during labour.
– It may be due to:
1. Contracted pelvis particularly flat pelvis which allows descent of the bitemporal but not the biparietal diameter leads to extension of the head.
2. Pendulous abdomen or marked lateral obliquity of the uterus.
3. Further deflexion of brow or occipito – posterior positions.
4. Other causes of malpresentation as polyhydramnios and placenta praevia.
Positions:
– Right mento-posterior (RMP).
– Left mento – posterior (LMP).
– Left mento-anterior (LMA).
– Right mento-anterior (RMA), are the more common positions.
Right mento- transverse (lateral), left mento-transverse, direct mento-posterior and direct mento-anterior are rare and usually transient positions.
1. The first position (RMP) corresponds to the first normal position (LOA) as the back should be to the left and anterior in the first position.
2. Mento-anterior are more common than mento-posterior as most cases arise from more deflexion of the head in occipito-posterior position usually in flat contracted pelvis.
Diagnosis:
(A) During pregnancy (difficult):
1. The back is difficult to feel.
2. The limbs are felt more prominent in the mento-anterior position.
3. The chin may be felt on the same side of the limbs as a horseshoe-shaped rim in the mento-anterior position.
4. In mento-posterior, a groove may be felt between the occiput and the back particularly after rupture of the membranes.
5. Second pelvic grip: the occiput is at a higher level than the sinciput.
6. The FHS is heard below the umbilicus through the fetal chest wall in mentoanterior position.
7. Ultrasound or X-ray: confirms the diagnosis and may identify associated fetal anomalies as anencephaly.
(B) During labour:
In addition to the previously mentioned findings. Vaginal examination shows the following identifying features for face:-
– supraorbital ridges,
– the malar processes,
– the nose ( rubbery and saddle-shaped),
– the mouth with hard areolar ridges. – the chin.
Brow Presentation
Definition:
It is a cephalic presentation in which the head is midway between flexion and extension.
Incidence: About 1:1000 labour.
Aetiology:
As face presentation.
Diagnosis:
(A) During pregnancy:
– It is difficult.
– The occiput and sinciput may be felt at the same level.
– Ultrasonography and X-rays may be helpful.
(B) During labour:
In addition to the previous findings, vaginal examination
reveals the following features:
– frontal bones,
– supra-orbital ridges, and
– root of the nose but not the chin.
Complex (Compound) Presentation
Definition:
It is the presence of a limb alongside the presenting part usually the arm presents with the head.
Incidence: About 1:800 labours.
Aetiology:
Interference of adaptation of the presenting part to the pelvic brim which may be:
(A) Fetal causes :
(1) Malpresentations.
(2) Prematurity.
(3) Multiple pregnancy.
(4) Polyhydramnios.
(B) Maternal causes:
(1) Contracted pelvis.
(2) Pelvis tumours.
Diagnosis:
Vaginal examination reveals limb beside the head.
BREECH PRESENTATION
Definition:
It is a longitudinal lie in which the buttocks are the presenting part with or without the lower limbs.
Incidence:
3.5% of term singleton deliveries and about 25% of cases before 30 weeks of gestation as most cases undergo spontaneous cephalic version up to term.
Aetiology:
In general, the fetus is adapted to the pyriform shape of the uterus with the larger buttock in the fundus and smaller head in the lower uterine segment.
Any factor that interferes with this adaptation, allows free mobility or prevents spontaneous version, can be considered a cause for breech presentation as :
1- Prematurity: due to
– relatively small fetal size,
– relatively excess amniotic fluid, and
– more globular shape of the uterus.
2- Multiple pregnancy: one or both will present by the breach to adapt to the relatively small room.
3- Poly-and oligohydramnios. 4-Hydrocephalus.
5- Intrauterine fetal death. 6-Bicornuate and septate uterus.
7- Uterine and pelvic tumors. 8-Placenta praevia.
Types:
(A) Complete breech:
– The feet present beside the buttocks as both knees and hips are flexed.
– More common in multipara.
(B) Incomplete breech:
(1) Frank breech:
– It is breech with extended legs where the knees are extended while the hips are flexed.
– More common in primigravida.
(2) Footling presentation:
– The hip and knee joints are extended on one or both sides.
– More common in preterm singleton breeches.
(3) Knee presentation:
The hip is partially extended and the knee is flexed on one or both sides.
Positions : ( 8 positions)
1- Left sacro- anterior.
2- Right sacro-anterior.
3- Right sacro – posterior.
4- Left sacro-posterior.
In addition to 5,6- left and right sacro – transverse (lateral). 7,8 – Direct Sacro- anterior and posterior.
Sacro-anterior positions are more common than Sacro-posterior as in the first the concavity of the fetal front fits into the convexity of the maternal spines.
Diagnosis:
(A) During pregnancy:
(I) Inspection:
1. A transverse groove may be seen above the umbilicus in Sacro-anterior corresponds to the neck.
2. If the patient is thin, the head may be seen as a localized bulge in one hypochondrium.
(II) Palpation:
1. Fundal grip: the head is felt as a smooth, hard, round ballottable mass which is often tender.
2. Umbilical grip: the back is identified and a depression corresponds to the neck may be felt.
First pelvic grip: the breech is felt like a smooth, soft mass continuous with the back. Trial to do ballottment to the breech shows that the movement is transmitted to the whole trunk.
(III) Auscultation:
FHS is heard above the level of the umbilicus. However, in frank breech it may be heard at or below the level of the umbilicus.
(IV) Ultrasonography:
It is used for the following:
1. To confirm the diagnosis.
2. To detect the type of breech.
3. To detect gestational age and fetal weight: Different measures can be taken to determine the fetal weight as the biparietal diameter with chest or abdominal circumference using a special equation.
4. To exclude hyperextension of the head.
5. To exclude congenital anomalies.
6. Diagnosis of unsuspected twins.
(B) During Labour:
In addition to the previous findings, vaginal examination reveals;
1. The 3 bony landmarks of breech namely 2 ischial tuberosities and tip of the sacrum.
2. The feet are felt beside the buttocks incomplete breech.
3. Fresh meconium may be found on the examining fingers.
4. Male genitalia may be felt.
Shoulder Presentation (Transverse or Oblique lie)
Definition:
The longitudinal axis of the fetus does not coincide with that of the mother.
These are the most hazardous malpresentation due to mechanical difficulties that occur during labour.
The oblique lie which is deviation of the head or the breech to one iliac fossa is less hazardous as correction to a longitudinal lie is more feasible.
Incidence:
3-4% during the last quarter of pregnancy but 0.5% by the time labour commences.
Aetiology:
Factors that
– change the shape of pelvis ,uterus or foetus,
– allow free mobility of the foetus or
– interfere with engagement as:
(A) Maternal:
1- Contracted pelvis.
2- Lax abdominal wall.
3- Uterine causes as bicornuate, subseptate and fibroid uterus.
4- Pelvic masses as ovarian tumours.
(B) Fetal causes:
1- Multiple pregnancy.
2- Polyhydramnios.
3- Placenta praevia.
4- Prematurity.
5- Intrauterine fetal death.
Positions:
The scapula is the denominator
1- Left scapulo – anterior.
2- Right scapulo – anterior.
3- Right scapulo – posterior.
4- Left scapulo – posterior.
Scapulo-anterior are more common than scapulo-posterior as the concavity of the front of the fetus tends to fit with the convexity of the maternal spines.
Diagnosis:
(A) During pregnancy:
(I) Inspection:
The abdomen is broader from side to side.
(II) Palpation:
a. Fundal level: lower than that corresponds to the period of amenorrhoea.
b. Fundal grip: The fundus feels empty.
c. Umbilical grip: The head is felt on one side while the breech one the other. In transverse lie, they are at the same level, while in oblique lie one pole, usually the head as it is heavier, is in a lower level i.e. in the iliac fossa.
d. First pelvic grip: Empty lower uterine segment.
(III) Auscultation:
FHS is best heard on one side of the umbilicus towards the fetal head.
(IV) Ultrasound or X-ray:
Confirms the diagnosis and may identify the cause as multiple pregnancy or placenta praevia.
(B) During labour:
In addition to the previous findings, vaginal examination reveals:
a. The presenting part is high.
b. Membranes are bulging.
Premature rupture of membranes with a prolapsed arm or cord is common. The dorsum of the supinated hand points to the fetal back and the thumb towards the head. The right hand of the fetus can be shaken, correctly by the right hand of the obstetrician and the left hand by the left one.
When the cervix is sufficiently dilated particularly after rupture of the membranes, the scapula, acromion, clavicle, ribs, and axilla can be felt.
Cord Presentation and Prolapse
Definitions :
In both conditions, a loop of the cord is below the presenting part. The difference is in the condition of the membranes; if intact it is cord presentation and if ruptured it is cord prolapse.
Incidence: 1:200.
The Risk:
As long as the membranes are intact there is no risk. In cord prolapse, the fetal perinatal mortality is 25-50% from asphyxia due to:
i) mechanical compression of the cord between the presenting part and bony pelvis and ii) spasm of the cord vessels when exposed to cold or manipulations.
The prognosis is worse when the cord is more liable for compression as in:
1. Primigravida than multipara.
2. Cephalic than breech presentation or transverse lie.
3. Partially than fully dilated cervix.
4. Generally contracted than flat pelvis.
5. Anterior than posterior position of the cord.
Aetiology:
(I) The presenting part is not fitting in the lower uterine segment due to:
(A) Fetal causes:
1- Malpresentations: e.g. complete or footling breech,
transverse and oblique lie.
2- Prematurity.
3- Anencephaly.
4- Polyhydramnios.
5- Multiple pregnancy.
(B) Maternal causes:
1- Contracted pelvis.
2- Pelvic tumours.
(II) Predisposing factors:
1- Placenta praevia.
2- Long cord.
3- Sudden rupture of membranes in polyhydramnios.
Diagnosis:
– It is diagnosed by vaginal examination. If the cord is prolapsed it is necessary to detect whether it is pulsating i.e. living fetus or not i.e. dead fetus but this should be documented by auscultating the FHS.
– Ultrasound: occasionally can diagnose cord presentation.