Operative Vaginal Delivery (ovd)

OPERATIVE (OVD) -

VAGINAL DELIVERY A NEW PERSPECTIVE

Although experts continue to argue about when a C/S should be performed, few would question the wisdom of maintaining and sharpening one’s skills in OVD. To accomplish that goal, we’ll review both forceps and vacuum extraction, look at current trends in clinical practice, and present the evidence to support the use of each approach.

Looking back before we look forward operative vaginal delivery has its origins in an era when fetal and maternal mortality and mortality rates were quite high. Often, the death of the fetus was deliberately induced in an effort to save a pregnant woman who had experienced a prolonged obstructed labor. But over time and with the introduction of new tools, operative vaginal delivery emerged as a way to both minimize maternal risk

At present, both forceps and the vacuum extractor (VE) are in widespread use. Controversy continues concerning if and when to conduct operative vaginal deliveries and which instrument is best. This and related issues are of importance because VE is currently used in about 6% of all births in the United States (nearly 50,000 operations per year).

Despite the growing popularity of VE, forceps remains the instrument of choice for many older clinicians for reasons of medical conservatism, inclination, and original training. The future for all instrumental delivery remains unclear, as adequate training in all aspects of these operations is increasingly difficult to obtain because of the retirement of classically trained obstetricians; the inability to conduct training operations; a malevolent medico-legal climate; and changes in practice, including the high frequency of cesarean delivery.

The rates of OVD, as well as the relative use of forceps in comparison to vacuum extraction, have varied considerably over time. There have been significant regional variations within the US and reduced rates of OVD overall and increased use of vacuum assisted devices as a percentage of OVDs. The percentage of births delivered by forceps declined from 5.5% to 2.8% and the vacuum extraction rate increased from

Mandatory Pre requisites 1.

Informed consent (IC) Not simply a signed form. Proper IC includes -explanation of the need for the operation - a discussion of risks and benefits - a presentations of alternative modes of treatment - opportunity to ask questions

2. Prepared physician - i.e. competent and well experienced.

3.

Prepared patients - Ruptured of -

4.

membranes Empty bladder Full Cervical dilatation Engaged head No suspicion of feto-pelvic disproportion

Acceptable analgesia/anesthesia Regional Major

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Pudendal block Epidural/Spinal

Indications Prolonged second stage This includes nulliparous woman with failure to deliver after 2 hours without, and 3 hours with, conduction anesthesia. It also includes multiparous woman with failure to deliver after 1 hour without, and 2 hours with, conduction anesthesia. Poor progress in labour requires caution, other abnormality like malpositioning, fetopelvic dropoportion may be present. An extended second stage is a relative but not absolute indication for obstetric intervention.

 Shortening of the second stage for maternal benefits: Maternal indications include, but are not limited to, exhaustion, bleeding, cardiac or pulmonary disease, and history of spontaneous pneumothorax. .Suspicion of immediate or potential fetal compromise in the second stage of labor. When prompt delivery is indicated, station and position of the fetal head, the feto-pelvic relationship, operator skill, and judgement of

In expert hands, fetal malposition, including the after-coming head in breech vaginal delivery, can be indications for forceps delivery. However operative vaginal delivery is appropriate in carefully selected cases of rapidly progressing labour when pelvic adequacy is good, the parturient is willing and able to assist and an experienced surgeon is present.

Trials

of

Instrumental

delivery

A trial of instrumental delivery is an operation in which delivery is indicated and the vaginal route remains a possibility, but the outcome is uncertain. In this type of procedure, the most experienced clinician remains at the perineum, encouraging maternal efforts of bearing down and assisting with an instrument, while other personnel simultaneously prepare for an urgent cesarean delivery. If the extraction does not proceed easily with descent of the presenting part beginning subsequent to the initial traction effort, the attempt at instrumentation is abandoned and a cesarean delivery is performed.

Contraindications to vacuum extraction  Operator inexperience  Inability to achieve a proper application  Inadequate trial of labor  Uncertainty concerning fetal position/station  Suspicion of feto-pelvic disproportion  High fetal head  Malpositioning (e.g. breech, face, brow)  Known or suspected fetal coagulation defect  Prior failed forceps Relative contraindications  Prematurity (fetuses <36 wk gestation)  Prior scalp sampling

VE Instrumentation -

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Rigid or flexible vacuum - Rigid cup – 1. Classic malmstrom stainless steel vacuum cup. 2. Rigid plastic cups for use with deflexed or posterior positioned heads. Flexible e.g. Polyethylene, silastic plastic. Attached Vacuum Pump A handle, wire or chain for traction

Soft flexible cups – have higher incidence of failure than either rigid or forceps, however they produce less cosmetic injury – scalp injury.

Technique Safety and success of VE depends on: 1. 2. 3. 4. 5.

The accuracy of cup application The traction technique Fetal cranal position and station at the time of application The cup design The fetopelvic relationship

Stages

1. 2. 3.

Ghosting Insertion Check application of cup (Identify anterior fontanelle/sagital suture line) 4. Traction: Traction efforts are timed to coincide with contractions.  Use of continuous vacuum through out the procedures versus intermittent vacuum with vacuum relaxed in between contractions. NO DIFFERENCES BETWEEN GROUPS WITH Respect to speed of delivery, rates of instruments failure or maternal or fetal outcome exist.

For standard VE – Recommendation 1. Limit the no of tractions to 4 or 5 2. Limit unintended cup detachments or “pop-offs” to 2 or 3 3. Requires advancement of the presenting part with initial traction 4. Restrict the overall duration of the procedure to 30 minutes (some propose 20 minutes). 5. Detailed documentation of the operative delivery in the medical records.



Sequential Instrument Use

(i.e. forceps operation followed by VE or Vice Versa) This is no longer recommended as this is associated with an increase risk of fetal intracranial haemorrhage.

BIRTH INJURIES Reported incidence of sever fetal injury or death from VE is low 0.1 to 3 cases per 1000 extraction procedures. Vacuum use results in shearing forces to the scalp. • Subgaleal/subaporenotic hage. This is the most feared complication of VE. Usually due to rupture of the emissary veins. Condition can be life threatening and a mortality rate reaching as high as 22.8%. Reported incidence of SG hage ranges from6 – 50 per 1000 VE operative deliveries, SG is rare unless excessive forces and / or multiple instrumentation is performed.

• Scalp bruising/lacerations/scalp sloughs This occur when recommended limits to total cup applications are exceeded. Cephal haematoma. Clinically unimportant Long term neonatal outcome Nil of significance in terms of neurological sequelae.

Maternal Injury Low rate of maternal injury in comparison to forceps. 1. Perineal Lacerations. Severe laceration i.e. 3rd and 4th degree reported incidence from 10 – 30%. Women with laceration in previous delivery are at a significantly greater risk. This is one area in which vacuum has a clear advantage. 2. Pelvic floor dysfunction (Stress Urinary and anal Incontinence). Recent studies evaluation outcome show no difference in these two conditions in mothers delivering with the aid of VE and forceps.

FORCEPS

DELIVERY

Forceps are instruments designed to aid in the delivery of the fetus by applying traction to the fetal head. Many different types of forceps have been described and developed throughout time. Generally, forceps consist of 2 mirror image metal instruments that are maneuvered to cradle the fetal head and are articulated, after which traction is applied to effect delivery.

Forceps have 4 major components, as follows: Blades: Shanks: Lock: Handles:

ACOG criteria for types of forceps deliveries

Outlet forceps: (1) The scalp is visible at the introitus, without separating the labia. The fetal skull has reached the pelvic floor. (2) The sagittal suture is in anteroposterior diameter, right or left occiput anterior or posterior position (i.e. the fetal head is at or on the perineum and rotation does not exceed 45o). Low forceps: The leading point of the fetal skull is at a station greater than or equal to +2 cm and is not on the pelvic floor; any degree of rotation may be present.

Mid forceps: The station is above +2 cm, but the head is engaged. High forceps: This is not included in the classification. Previous systems classified high-forceps deliveries as procedures performed when the head is not engaged. High-forceps deliveries are not recommended.

Prerequisites for forceps delivery include the following: The head must be engaged The cervix must be fully dilated and retracted The position of the head must be known The type of pelvis should be known The membranes must be ruptured No disproportion should be suspected between the size of the head and the size of the pelvic inlet and mid pelvis.

The patient must have adequate anesthesia. Adequate facilities and supportive elements should be available The operator should be fully competent in the use of the instruments and the recognition and management of potential complications. The operator should also know when to stop so as not to force the issue.

Contraindications: The following are contraindications to forceps-assisted vaginal deliveries: Any contraindication to vaginal delivery Refusal of the patient to consent to the procedure Cervix not fully dilated or retracted Inability to determine the presentation and fetal head position or pelvic adequacy Cephalopelvic disproportion Unsuccessful trial of vacuum extraction (relative contraindication) Absence of adequate anesthesia Inadequate facilities and support staff Inexperienced operator

Maternal complications  Early (i.e. acute) complications include (1) lacerations to the cervix, vagina, peril bladder; (2) extension of episiotomies; (3) increase in blood loss; (4) hematoma intrapartum rupture of the unscarred uterus.  Late complications are mainly related to injury to the pelvic support tissues and include (1) urinary stress incontinence, (2) fecal incontinence, (3) anal sphincter, (4) pelvic organ prolapse.

• Fetal complications

 Transient facial forceps marks, bruising,lacerations, and cephalohematomas  Facial nerve injuries may be seen  Skull fractures, intracranial hemorrhage with falx, or tentorial lacerations have a been reported  Reports exist of an increased incidence of shoulder dystocia in patients delivered with forceps, although this had not been confirmed in other studies.  Cerebral palsy, mental retardation, and behavioral problems may be more related to the episodes that required emergent delivery or other intrapartum, environmental, operative factors

CHOICE OF INSTRUMENT Debate among clinicians persists concerning which instrument is best either the vacuum or forceps. Factors Involved • Anaesthesia • Instrument failure • Serious birth injury

Outlet/low pelvic operation rotation < 45% with adequate analgesia vacuum & forceps are equivalent instruments. Low-pelvic operations (relation > 45) and mid pelvic operations – VE. Forceps can be used in direct face to press & rotation in an experienced hand. Breech presentation – Piper or Kjellard forceps. Multiple gestations – delivery of second presenting cephalic – vacuum must suitable. Prematurity < 36 wk The use of any instrument to assist delivery of a premature infant is controversial. The conclusion is that a great caution must be exercised

In clinical practice the accocheur must consider: 1. The fetal condition 2. The available resources 3. Extent of contractions and likelihood of maternal cooperation 4. Personal skill level Greater success and less danger result when instruments are chosen based on operator experience and skill.

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In presumed fetal jeopardy at low station many prefer to apply forceps rather than vacuum however trials have demonstrated no difference. When no urgency required then careful attention to palpation of the cranial fontanelles, suture lines, orbital ridges or the fetal ear helps establish the correct cranial orientation. In difficult cases, real-time ultrasound scanning is useful in evaluating fetal cranial position. The instrument chosen should best fit the clinical condition.

Developing one’s technique To perform a safe and successful OVD, a clinician must be welltrained and observe proper technique. He or she should do the following. • Perform clinical pelvimetry to determine adequate mid- and outlet-pelvic dimensions and ensure to obstructions or contractures exist; • Provide adeq2uate maternal anesthesia should be in effect; • Assess fetal size, presentation, position, lies, and any asynclitism; • Determine the level of engagement of the fetal head as precisely as possible.