VENTOUSE DELIVERY

VENTOUSE DELIVERY

Introduction

            Simpson introduced the idea of vaccum extraction in the 1840’s and there have been numerous attempt since to attach a traction device by suction to the fetal scalp. In the united state the device referred to as vaccum extractor , while commonly it is referred to as ventouse. (from French literally soft cup)

Definition

            Ventouse  is an instrumental device designed to assist delivery by creating a vaccum between it and the fetal scalp. The pulling force is dragging the cranium while in forceps. 

Instruments

Eversince Malmstrom , in 1956 reintroduced and popularized its use , various modifications of the instruments are now available.

Components of instruments

            Metal cups were initially used , soft cups , silic cup { silicon rubber or disposable plastic (mityvac)}. Cups have better adherence to the fetal scalp. The cup could be folded and introduced into the vagina without much discomfort. The cup is connected to a pump through a thick wall rubber tube by which air is evacuated. Vaccum is created by a hand pump or by electric pump.

The part of the devices are

1. Suction cup with 4 size (30, 40, 50, and 60mm)
2. A vacuum  generator
3. Traction tubing

Indications of ventouse

®    An alternatives to forceps operation

®    As an alternative to rotational forceps as in occipito transverse or posterior position

®    Delay indecent of the head incase of the second baby of twins

®    Delay in last first stage of labour (uterine inertia )

Advantages of ventouse over forceps

®    It can be used in unrotated and malrotated occipito posterior position of the head.

®    It can be applied even through incompletely dilated cervix (first stage of labour )

®    It is not space occupying device like the forceps blade

®    Lessor traction force is needed (10 kg )

®    It can be used safly even when the head remains at a high level and exact position is unsure

®    It is comfortable and injuries to the mother are less.

®    Requires  less technical  skills (suitable for trained midwives )

Contraindications

¨      Any presentation other than vertex presentation ( face , brow , breech )

¨      Preterm fetus ( <34weeks ) :- chance of scalp avulsion or sub-apo neurotic hemorrhage

¨      Suspected fetal coagulation disorders

¨      Suspected fetal macrosomia

Condition to be full filled

¨      There should not be slightest bony resistance below the head. 

¨      The head of a singleton baby should be engaged

¨      Cervix should be at least 6cm dilated

Procedure

Pudental block or perineal infiltration with 1% lignocaine is sufficient. It may be applied even without anaesthesia  specially in parouse woman. The instruments should be assembled and the vacuum is tested prior to its application.

Steps 1:-  Application of the cup

The largest possible cup according to the dilatation of the cervix is to be selected. The cup is introduced after retraction of the perineum with two fingers of the other hand. The cup is placed against the fetal head nearer to the occiput with the knob of cup pointing towards the occiput. This will facilitate flexion of the head , and the knob indicate the degree of rotation.

A vacuum of 0.2kg/cm2 is induced by the pump slowly, taking at least 2mts. A cheek is made using the fingers round the cup to induce that no cervical or vaginal tissue is trapped inside the cup. The pressure is gradually raised at the rate of 0.1kg /cm2 per minutes until the effective vacuum of 0.8kg/cm2 is achieved in about 10mts time. the scalp is sucked in to the cup and an artificial caput succedaneum (chignon) is produced. The chignon usually disappears with in few hours.

Step 2 :- Traction

ü  Traction must be at right angle to the cup

ü  Traction should be synchronous with the uterine contraction

ü  Traction should be made using one hand along the axis of the birth canal. The fingers of the other hand are to be placed against the cup to note the correct angle of traction, rotation and advancement of the head .

ü  If there is no advancement during four successive traction,it is to be abandoned on no account , traction should exceed 30mts

ü  As soon as the head is delivered , the vacuum is reduced by opening the screw – release valve and cup is then detached. The delivery is then completed in the normal way

Complication

Fetal

ü  Superficial scalp abrasion

ü  Sloughing of the scalp

ü  Cephalhaematoma – due to rupture of emissary veins beneath the periostium

ü  Subaponeurotic (subgaleal ) haemorrhage (not limited by suture line as it is not subperiosteal)

ü  Intracranial hemorrhage (rare)

ü  Retinal haemorrhage ( no long term efforts )

Maternal

The injuries are uncommon but may be due to inclusion of the soft tissues such as the cervix or vaginal wall inside the cup.