Methods Of Induction - 2

AMNIOTOMY (Artificial Rupture of Membranes)
This is done to initiate labour (surgical induction) or, during labour, to try to accelerate the process, or to allow a fetal scalp electrode to be applied or to permit estimation of the fetal pH. Amniotomy appears to release a local secretion of endogenous prostaglandins.

Amniotomy, using a
Hollister Amnihook or
other device, may be used
to rupture the membranes
overlying the presenting
part. Care must be taken
not to damage the fetal
tissues.The operation may
be done blindly by passing
the instrument along the
fingers or by direct vision
using a speculum.

The procedure is carried out using an aseptic technique and sometimes sedation or even epidural anaesthesia may be required to permit adequate examination.The colour and quantity of the liquor removed should be noted. Prolapse of the umbilical cord should be excluded at the beginning and end of the procedure.

Complications of Amniotomy

Failure to induce effective contractions
Labour may not become established after amniotomy alone and it is usual to stimulate the uterus further by intravenous oxytocin after an interval of 3 hours or so if contractions are inadequate.

Placental separation (Abruption)

This may be caused by the sudden reduction in the volume of liquor where there has been polyhydramnios.

Bleeding

This is not uncommon.The usual source is maternal blood from an element of forced
dilatation of the cervix by the examining fingers. Occasionally it may come from fetal vessels running in the membranes (velamentous insertion of the cord).The best method of identifying the source of blood is by Kleihauer’s test, a laboratory procedure, by which a blood slide is so stained as to show the fetal cells standing out in a field of ‘ghost’ maternal cells.

Prolapse of the cord

This will only happen with an ill-fitting presenting part. Cord prolapse, occult or frank, should give warning signs on the Fetal Heart Rate monitor.

Infection

The uterus may become infected if the interval from amniotomy to delivery is excessive, and both mother and child are at risk. Infection may perhaps be delayed by observing carefull antiseptic techniques, and by exhibiting antibiotics whenever delay is anticipated.

Pulmonary embolism of amniotic fluid

This rare condition presents as severe shock of rapid onset, with intense dyspnoea and often bleeding. It is associated with amniotomy and strong uterine contractions, and must be distinguished from eclampsia, abruption, ruptured uterus, and acid aspiration.Treatment must include positive pressure ventilation, and correction of the inevitable coagulation defect. Post mortem examination of the maternal lungs will show fetal cells and lanugo.

Category: Obstetrics Notes