1. Occipito-Posterior Position:

It is a vertex presentation in which the occiput is placed posteriorly. It can be:-

1. Right occipito-posterior (commonest)
2. Left occipito-posterior.
3. Direct occipito-posterior

Incidence:

In 20% of cases the occiput is posterior at the beginning of labour.

1.1. Causes:

1. Pelvic Factors: 50% of cases are associated with anthropoid pelvis or android pelvis.
2. Fetal Factors: Marked deflection of the fetal head due to high pelvic inclination or anterior wall placenta.
3. Uterine Factor: Abnormal uterine contraction which may be the cause or effect.

1.2. Diagnosis:

• Features suggesting the diagnosis include:
  • Backache during labour.
  • Flattening of the abdomen below the umbilicus.
  • The fetal limbs are more easily felt near the midline on both side.
  • The head is unengaged and feel larger than usual.

• Vaginal examination:
  • Elongated bag of membrane which is likely to rupture early.
  • High deflexed head with the  anterior fontanelle in the centre of the pelvis.

1.3. Mechanism of labour:

• First and second stage of labour usually prolonged.
• Membrane usually rupture early with the hazards of cord prolapse and infection.
• In favorable circumstances (90% of cases) good uterine contraction result in good flexion of the head and the occiput rotates 3/8 of the circle (135C⁰) anteriorly and deliver as occipito-anterior position.
• In unfavorable circumstances (10% of cases) the occiput:
  • Fail to rotate and remain in the oblique diameter of the pelvis.
  • Rotate anteriorly 1/8^th of circle (short rotation) and the head become arrested in the transverse diameter of the pelvis (deep transverse arrest).
  • Rotate posteriorly 1/8^th of the circle to lie on the sacral hollow this called direct-occipito-posterior position. And if the fetus is small & pelvis is Adequate spontaneous delivery can occur as face to pubic.

1.4. Management:

• Unless there is fetal hypoxia or other complication labour is allowed to proceed with the following special instructions:
  • Provide adequate analgesia (an epidural is ideal).
  • Prevent dehydration with intravenous fluid glucose.
  • You may need to promote uterine contraction with oxytocin.
  • Good monitoring for progress of labour, fetal condition and maternal condition.
• In the majority of cases anterior rotation of the occiput is completed and the baby is delivered as occipito-anterior.
• In direct occipito-posterior delivery as face to pubis may occur, The perineum should be protected by a generous episiotomy.
• Persistent-occipito posterior and deep transverse arrest: If the fetal head is not engaged caesarian section is the treatment of choice.
• If the fetal head is engaged the treatment will be one of the following:
  • Manual rotation and delivery by forceps as occipito-anterior.
  • Rotation to occipito-anterior and extraction using kielland’s forceps.
  • Ventouse (vacuum extraction).
  • Caesarean section if the above lines of treatment fail or there is other complicating factor.
  • Craniotomy when the fetus is dead .

2. Face Presentation:

• The head is completely extended so that the occiput is in contact with the back.
• The denominator is the mentum (chin) with 4 main position recognized:
  • Rt. & Lt. mento-anterior.
  • Rt. & Lt. mento-posterior.

Incidence: (about 1in 500births)

2.1. Causes:

In many cases there is no obvious cause

1. Anencephaly (10%)
2. Prematurity (25%)
3. Multiple pregnancy.
4. Loops of cord around the neck and a swelling in the neck such as goitre or cystic hygroma.

2.2. Diagnosis:

• On abdominal examination there is depression between the anterior shoulder and the head prominence.
• The fetal heart sounds are heard best on the same side as the limbs.
• Vaginally the mouth, nose and orbits can be felt.

2.3. Management:

• Most mento-anterior positions deliver spontaneously or by a low forceps.
• Mento-posterior cannot deliver vaginally but around half will rotate spontaneously. So mento-posterior should be managed expectantly.
• A persistent mento-posterior requires rotation either manually or by kielland’s forceps & then extraction or very commonly caesarean section.

3. Brow Presentation:

The head lies in between full flexion and full extension.

Incidence: (about 1:1000 births).

3.1. Causes:

1. Anencephaly (10%)
2. Prematurity (25%)
3. Multiple pregnancy.
4. Loops of cord around the neck and a swelling in the neck such as goitre or cystic hygroma.

3.2. Diagnosis:

On P.V the supra-orbital ridges and anterior fontanelle are palpable but not the nose, mouth or chin.

3.3. Management:

• In early labour brow presentation may flex  to become a vertex or extend further to a face presentation  both are potentially deliverable vaginally.
• If the brow presentation persists into or is discovered in established labour, delivery should be by caesarean section.

4. Compound presentation:

• One or more limbs present with the head or the breech. Most commonly a hand with the vertex.
• The commonest cause is prematurity, others are contracted pelvis, pelvic tumour, poly hydramnios and dead fetus.
• The main complication is prolapse of the cord.

5. Transverse and oblique lies:

Occurs when the long axis of the fetus crosses that of the mother with the head on one side and breech on the opposite side of the midline.

Incidence: (1in 200 births)

5.1. Etiology:

1. Multiparity
2. Prematurity
3. Multiple pregnancy
4. Poly hydramnios
5. Placenta praevia
6. Pelvic tumor
7. Congenital malformation of the uterus
8. IUFD
9. Contracted pelvis

5.2. Diagnosis:

• The uterus is broad and asymmetrical.
• The fundal height is less than date.
• The fetal head is on one side and the breech in the other .
• Pelvic inlet feels empty but during labour may be occupied by the shoulder
• On vaginal examination the presenting part is high and difficult to define.
• The membrane  rupture early in labour and the cord may prolapse.
• During labour the shoulder is identified by palpating the following parts acromion process, the scapula, the clavicle and axilla, feeling of the ribs and intercostals spaces, on occasion the arm is found prolapse.

5.3. Management:

The first line of management is exclusion of a specific cause. ECV followed by rupture of membranes and oxytocin infusion is used by some. However unless there is rapid and easy correction, C/S should be performed.