50-instrumental Vaginal Delivery

Instrumental vaginal delivery refers to the use of specially designed instruments, namely the obstetric forceps and the vacuum extractor, to facilitate delivery of the fetal head.

Their use is usually restricted to certain difficult deliveries in order to shorten the second stage of labour whenever fetal or maternal distress is already present, or strongly anticipated. The decision to choose between the obstetric forceps or the vacuum extractor is individualized according to each case and is largely dependant on the clinician's state of experience.

The liberal use of instrumental delivery in obstetric practice has been hindered by the increased maternal and fetal complications associated with the inappropriate use of such instruments. In the last 2-3 decades, delivery by C.S. has replaced most of the difficult instrumental techniques.

THE OBSTETRIC FORCEPS THE INSTRUMENT  The obstetric forceps is an instrument designed for traction or combined traction and rotation of the fetal head.  It consists of two blades, each having two curves: Cephalic curve to fit on each side of the fetal skull. Pelvic curve to obtain a central grip on the head and to promote flexion.

Each blade consists of: - The Blade proper, that fits on the head. - The Shank, that connects the blade to the handle. - The Lock, where the two blades cross each other - The handle, by which traction is done. Each blade is fenestrated: - To minimize compression - To make its weight lighter - To prevent slipping as the parietal eminences protrudes through the fenestration

CLASSIFICATION OF FORCEPS OPERATIONS Outlet forceps: Fetal head is at the perineum Sagittal suture in anterior or posterior diameter (DOA-DOP). Rotation is < 45º (ROA-LOA). Low Forceps: Fetal head is at station (+2, or more), but not on perineum Rotation is > 45º Mid forceps: fetal head at station (0 to +1), with rotation > 45

TYPES OF OBSTETRIC FORCEPS 1. The Long curved forceps 3. The Short forceps 5. The Kielland forceps 7. The Pippers Forceps

The Long curved forceps  The Long curved forceps “15 inches”: mainly used for mid forceps delivery.

The Short forceps   

The Short forceps “11 inches”: mainly used for low forceps delivery. The handle & the shank are shortened. It is either: Curved (Wrigley’s forceps) Straight (Simpson forceps)

The Kielland forceps  It is a long forceps designed mainly to facilitate traction and rotation of the fetal head in occipitoposterior positions.

It is characterized by:  The blades are called anterior & posterior.  Beveled inner surface of the blade: to minimize fetal head injury  Minimal Pelvic Curve: allowing rotation & Traction by single application.  A Sliding lock: to allow application on asynclitic head  Knobs on the handle that should be directed toward the fetal occiput.

The Pippers Forceps  It is a long forceps designed to facilitate delivery of the after coming head in breech presentation.

 It is characterized by a long shank with the

presence of a perineal curve.  It promotes flexion of the fetal head.  It prevents sudden compression and decompression on the fetal head.  It allows safer traction on the after coming head and not on the fetal neck.

INDICATIONS FOR THE USE OF FORCEPS      

Prolonged second stage of labour. To shorten second stage of labor. Inadequate maternal expulsive forces. Fetal distress if the cervix is fully dilated. Prolapsed pulsating cord with fully dilated cervix. Some Malpositions & malpresentations: - O.P. after failure of spontaneous rotation. - After coming head in breech.

PREREQUISITES BEFORE FORCEPS APPLICATION       

The cervix should be fully dilated. The head should be engaged. Cephalopelvic disproportion should be excluded. The membranes (forewaters) should be ruptured. Presence of adequate uterine contractions Antisepsis and anaesthesia The bladder & rectum should be evacuated

CONTRAINDICATIONS TO FORCEPS OPERATION     

Incompletely dilated cervix Unengaged head Cephaloopelvic disproportion Intact membranes Uterine inertia

N.B: The ideal application of forceps is Cephalopelvic application. N.B.: One of advantages of forceps is that it can be applied on face presentation and on after coming head in breech deliveries. Prematurity is a relative contraindication, it may be injurious if used with excessive force, in the same time it may protect the head from sudden compression and decompression.

COMPLICATIONS OF FORCEPS PROCEDURES A) Maternal complications: 1. Maternal birth injuries 2. Postpartum hemorrhage (PPH)

B) Fetal complications: 1- Intracranial hemorrhage 2- Head & Skull injuries

HISTORICAL REVIEW  The introduction of obstetric forceps in modern obstetrics has been credited to Chamberlen's family, who practiced midwifery in England for four generations, in the 18th century. They kept their forceps as a family secret for nearly 100 years.  During the next 200 years, endless innovations have been introduced to the original simple instrument.

• Special types of forceps have been designed to facilitate its use in certain situations as with the Kielland forceps and Piper's forceps. • The most commonly used forceps nowadays are the short forceps (Wrigley & Simpson forceps), used mainly in low and outlet forceps.

THE VACUUM EXTRACTOR

INTRODUCTION  The use of vacuum–cup deliveries to facilitate vaginal birth dates back to 18th century. The idea was to apply traction to fetal scalp guiding the head down out of the birth canal. In 1954, Malmstrom, (a Swedish obstetrician), developed the currently used vacuum extractor.

 Original Malmstrom ventouse used a metal cup applied on fetal scalp for traction, and a glass jar and pump to create a negative pressure.  Current instruments use pliable plastic and polyethylene cups, and electric suction instruments for negative pressure production.

PREREQUISITES FOR THE USE OF VACUUM EXTRACTOR (AS FORCEPS):  The cervix should be fully dilated.  The head should be engaged.  Cephalopelvic disproportion should be excluded.  The membranes (forewaters) should be ruptured.  Presence of adequate uterine contractions  Antisepsis and anaesthesia  The bladder & rectum should be evacuated

INDICATIONS FOR USE OF VACUUM EXTRACTOR (AS FORCEPS):  Prolonged second stage of labour.  To shorten second stage of labor.  Inadequate maternal expulsive forces.  Fetal distress if the cervix is fully dilated.  Prolapsed pulsating cord with fully dilated cervix.  Some Malpositions & malpresentations: - O.P. after failure of spontaneous rotation. - After coming head in breech.

CONTRAINDICATIONS TO THE USE OF THE VACUUM EXTRACTOR     

Incompletely dilated cervix Unengaged head Cephaloopelvic disproportion Intact membranes Uterine inertia

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Non vertex presentations, as in face and breech presentations. Premature infants, to avoid serious complications. Marked fetal distress, as it needs a longer period of application than the forceps.

 

Advantages of the Vacuum extractor  Allows easy and gentle traction on the fetal head, due to limited force.  Promotes flexion and helps internal rotation of the fetal head in O.P. positions.  Less encroachment on maternal pelvic space, resulting in less trauma to maternal birth canal, and less serious lacerations

Complications of the vacuum extractor A) Maternal complications:   

Vaginal and perineal lacerations. Cervical lacerations. Rarely rupture uterus, (non engaged head, or non fully dilated cervix).

B) Fetal complications:   

Cephalhaematoma. Scalp lacerations, (excessive force and repeated slipping of the cup). Cerebral hemorrhage (tear of vein of Gallen).

Technical Considerations 

To promote flexion of the fetal head with traction, the suction cup is placed over the ' median flexing point ‘.

 Low suction (100 mmHg) is applied. After ensuring that no maternal soft tissue is trapped between the cup and fetal head, suction is increased to 500600 mmHg and sustained downward traction is applied along the pelvic curve in concert with uterine contractions.

 Suction is released between contractions.  The procedure should be abandoned if the cup detaches three times or if no descent of the head is achieved.