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Obstetrics Simplified - Diaa M. EI-Mowafi

Dystocia due to Oversized Foetus


CAUSE MANAGEMENT
(I) Generalised foetal enlargement (macrosomia) See later.
(II) Localised foetal enlargement

(1) Hydrocephalus

(2) Meningocele or encephalocele

  

See later.

If small: no effect as it will be flattened or ruptured.
If large: tapping of the cyst.
(3) Abdominal ascitis Tapping.
(4) Abdominal tumours Evisceration but if huge do caesarean section.
(5) Foetal monsters (conjoined twins) Caesarean section is the safest.
(6) Shoulder dystocia See later.

GENERALISED FOETAL ENLARGEMENT (MACROSOMIA)

Definition

A foetal weight of more than 4 kg.

Causes

  • Genetic or constitutional: large women tend to give birth to large babies.
  • Diabetes and prediabetes.
  • Post-date (postmaturity).
  • Multiparity: The first baby is about 100 gm smaller than the next.
  • Hydrops foetalis.

Risk Factors

  • Excessive maternal weight gain during pregnancy.
  • Advanced maternal age.
  • Male foetus than female.
  • Previous macrosomic infant.

Diagnosis

  • Clinical palpation: can give a rough idea.
  • Ultrasonography: can calculate the foetal weight.

Hazards

  • Prolonged pregnancy
  • Cephalopelvic disproportion
  • Obstructed labour.
  • Shoulder dystocia.
  • Meconium aspiration syndrome.
  • Nerve and bone injuries.
  • Future baby obesity.

Management

  • Proper antenatal care: to prevent macrosomia and diagnose it before labour commences.
  • Caesarean section: is the safest for both mother and foetus .

HYDROCEPHALUS

Definition

It is an enlargement of the foetal head due to accumulation of excessive cerebro-spinal fluid (C.S.F) within the ventricles.

Incidence

0.5-1.8 per 1000 births. Incidence of recurrence in subsequent pregnancy is about 3%.

Aetiology

  • Obstruction of Aqueduct of Sylvius which may be due to:
    • Genetic aberration as trisomies.
    • Infections: as cytomegalovirus, toxoplasmosis and rubella.
    • No detected cause.

Diagnosis

During pregnancy

  • Breech presentation in 50% of cases.
  • Head is large with soft bones.

During labour

  • Cephalic presentation:
    • High non-engaged head.
    • Thin compressible skull bones.
    • Wide sutures and large fontanels.
  • Breech presentation:
    • Retained large after-coming head.     
    • Spina bifida is common (30%).

X-ray and ultrasound

  • Large head with biparietal diameter >12 cm (not in every case).
  • Dilated cerebral lateral ventricles each measures >1.5 cm and together >1/3 the biparietal diameter (more diagnostic).
  • Small face in relation to the head size.
  • The thickness of cerebral cortex which determines postpartum prognosis of the foetus can be measured by ultrasound.

Complications

  • Obstructed labour: with its sequel as rupture uterus. This is more common in mild degrees of hydrocephalus which cannot be detected before or during labour.
  • Foetus: Still birth or live birth with neurological manifestations and low growth rate.

Management

Antepartum

  • Ventriculo-amniotic shunt:
    • With the recent advances in intrauterine foetal therapy ventriculo-amniotic shunt with a one way valve can be done to drain the CSF from the cerebral ventricles into the amniotic cavity preventing compression of the brain tissues.
  • Induction of preterm labour: after draining of the fluid through a transabdominal needle puncture.

Intrapartum

  • Cephalic presentation:
    • If the cervix is dilated: transcervical aspiration by a needle or perforation through a gaping suture or fontanelle is done.
    • If the cervix is not dilated: transabdominal aspiration by a needle is done.
    • Traction on the collapsed head can then applied by Willet’s scalp forceps.
  • Breech presentation:
    • CSF is drained through:
    • perforation in the roof of the mouth, foramen magnum or behind the mastoid process.
    • Spinal tapping which is easier through spina bifida if present.

Postpartum

The living newborn should be referred for shunt operation to drain the cerebral ventricles into the jugular vein or right atrium.

SHOULDER DYSTOCIA

Definition

It is a difficulty in shoulder delivery.

Incidence

About 0.5% of deliveries.

Causes

  • Large shoulders which may be due to:
    • Maternal obesity.
    • Diabetic mothers.  
    • Post-term pregnancy.
    • Anencephaly.
  •   Failure of shoulder rotation.
  •   Contracted and platypelloid pelvis.

Prediction

  • Presence of risk factors of macrosomia (see before).
  • Ultrasonographic assessment of foetal weight.

Clinical Picture

  • The head is delivered and the chin is applied firmly against the perineum.
  • There is no further progress in spite of gentle traction on the head.

Management

Prophylaxis

Proper antenatal care particularly for high risk mothers as diabetics.

Antepartum assessment of foetal weight: macrosomic babies should be delivered by caesarean section.

Shoulder dystocia

Calling urgently an anaesthetist and paediatrician.

The following methods are used in a rapid succession when the previous one failed:

  • Rotation of the anterior shoulder: if unrotated by fingers transvaginally to bring it in the antero - posterior diameter.
  • Generous episiotomy + gentle downward traction + suprapubic pressure by an assistant obliquely to flex the anterior shoulder against the foetal chest.
  • Mc Roberts' manoeuvre: It is sharp flexion of the maternal thighs against her abdomen. This can free the shoulders by:
    • backward displacement of the sacral promontory.
    • upward displacement of the symphysis pubis.
    • Decrease the inclination of the pelvic inlet.
    • Decrease in lumbar lordosis.
  • Woods screw manoeuvre:
    • Woods (1943) described this manoeuvre to rotate the foetus as a screw between the resisted promontory and symphysis.
    • Two fingers of the right hand is pressing from the posterior aspect of the posterior shoulder to rotate it 180o anteriorly where it escapes from below the symphysis.
    • The left hand is placed on the mother’s abdomen and assists this rotation by pressing on the foetal buttock in the same direction of rotation.
  • Extraction of the posterior arm: by pressing with 2 fingers against the cubital fossa to sweep the posterior arm in front of the chest and deliver it giving space for the anterior shoulder to escape from below the symphysis.This is aided by suprapubic pressure.
  • Zavanelli manoeuvre (cephalic replacement):
    • Prepare for caesarean section.
    • Subcutaneous terbutaline (tocolytic) is given to relax the uterus.
    • Rotate the head manually to the antero-posterior diameter (pre-restitution position).
    • Flex the head and press on it firmly and constantly to replace it intravaginally where it is supported by an assistant.
    • Immediate caesarean section is performed.
  • Clavicular fracture:
    • was described to reduce the diameter of the shoulders. It is done by upward pressure against its midportion to avoid injury of the subclavian vessels.
  • Cleidotomy:
    • It is cutting of the clavicle and usually reserved for a dead foetus.
  • Symphysiotomy:
    • It is advocated by some authors to overcome contracted pelvis in women living in uncivilised areas.

Complications

  • Foetal:
    • Asphyxia and death.
    • Brachial plexus injury causing Erb's palsy.
    • Fracture clavicle or humerus.
  • Maternal:
    • Injuries from manoeuvres which may extend up to rupture uterus.

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