Vacuum Extraction

Anatomy and Physiology

For proper use, the maternal cervix should be fully dilated, the head engaged in the birth canal, and the head position known. The baby should not be preterm, previously exposed to sampling from the scalp, or failed forceps delivery. If the attempt fails, it may be necessary to deliver the infant by cesarean section or forceps.  The bladder should be empty, and the facility should be able to accommodate a stat cesarean section should operative delivery attempts be unsuccessful.  

Indications

Prerequisites for Operative Vaginal Delivery

• Cervix fully dilated
• Membranes previously ruptured
• Engagement of the fetal head
• The clinician has determined the position of the fetal head
• Fetal weight estimation performed previously
• Pelvis thought to be adequate for vaginal delivery
• Adequate anesthesia (often an epidural)
• The maternal bladder has been emptied
• The patient agrees to the procedure after informed consent
• A backup plan in case of failure is in place (typically cesarean delivery).

Classification of Operative Vaginal Deliveries

Extraction is classified by the status of the fetal head at the time of vacuum application and the degree of rotation necessary.

Outlet delivery

• The scalp is visible at the introitus without separating the labia.
• The fetal skull has reached the pelvic floor.
• The fetal head is at or on the perineum.
• The sagittal suture is in AP or ROA/LOA or OP position.
• Rotation does not exceed 45 degrees.

Low delivery

• The leading point of the fetal skull is at station +2 or more and not on the pelvic floor.
• Without rotation: Rotation is 45 degrees or less
• With rotation: Rotation is greater than 45 degrees

Mid delivery

• The station is above +2, but the head is engaged.

Contraindications

Certain fetal conditions such as fetal bleeding disorders (e.g., hemophilia, neonatal alloimmune thrombocytopenia, Von Willebrand's disease), fetal demineralizing diseases (e.g., osteogenesis imperfecta) preclude the use of a vacuum to expedite delivery. Its use is discouraged at less than 34 weeks estimated gestational age. Prior to its use, the obstetrician should ensure that all of the above prerequisites have been met and the patient agrees to the care plan.  

Equipment

Vacuum extractors often have replaced forceps when assistance is required for vaginal delivery. Compared with metal-cup vacuum extractors, soft-cup devices cause fewer neonatal scalp injuries and are easier to use; however, they detach more often.

Vacuum extractors can result in neonatal injury. These devices should be employed only when indicated, such as for a nonreassuring fetal heart tracing or second-stage labor failure to progress. Complications may be minimized if contraindications are considered. Clinicians should have adequate training and experience before attempting to perform a vacuum-assisted vaginal delivery.[4][5][6][7]

Personnel

Operator and at least one assistant should be present at the time of vacuum-assisted vaginal delivery. In addition, personnel should be available to assist with infant resuscitation if needed.

Technique or Treatment

After ensuring that all the prerequisites for operative vaginal delivery have been met, the vacuum cup is applied to the fetal scalp. The cup is placed symmetrically astride the sagittal suture at the fetal pivot point. The fetal pivot point is located approximately two centimeters anterior to the posterior fontanelle or six centimeters posterior to the anterior fontanelle. It should not be placed directly over the fontanelle. Correct placement will assist with flexion, descent, and rotation of the vertex when traction is applied, minimizing the risk of injury to both the fetus and the maternal soft tissues. Before applying suction, it is important to sweep a finger around the cup to ensure no intervening vaginal or cervical tissues between the cup and the fetal scalp. Once an appropriate placement is confirmed, suction can then be applied. Vacuum pressures are then raised to the desired pressure, often indicated by a green zone on many devices. Downward traction is then applied along the pelvic curve using the dominant hand. The other hand monitors the progress of descent and prevents cup detachment by applying counter pressure to the cup. Traction is applied during contractions and maternal expulsive efforts. The suction is removed, and the cup is detached once the fetal head is crowning. The rest of the delivery is then carried out in the usual manner.

Should the device disengage during delivery attempts, additional attempts may be initiated. Manufacturers discourage more than two to three attempts (or pop-offs), and clinicians should proceed with cesarean section.[8][9]

Complications

Maternal complications include the extension of vaginal lacerations, including sphincter and vaginal pain.

Newborn complications include scalp lacerations, cephalohematoma, intracranial hemorrhage, retinal hemorrhage, hyperbilirubinemia, and neurological injury. Absolute rates of complications are low; it is estimated that the rate of intracranial hemorrhage following operative vaginal delivery is at one in 650 to 850 live births.

Clinical Significance

The decision to continue with operative vaginal delivery should continuously be re-evaluated during the delivery progresses. If there is no descent, further attempts should be discontinued and cesarean section considered.

Rocking motions and applying torque to achieve rotation should be avoided.

The maximum time to safely complete a vacuum extraction and the acceptable number of detachments are unknown. It is recommended that vacuum-assisted deliveries be achieved with no more than three sets of pulls and a maximum of two to three cup detachments or pop-offs. The total vacuum application time should be limited to 20 to 30 minutes.

Sequential application of the vacuum and the forceps or vice versa is discouraged due to a higher risk of fetal and maternal injury.

Advantages of Vacuum Extraction and Forceps

Vacuum Extractors 

• Easy to learn
• Quick delivery
• Less neonatal craniofacial injury
• Less maternal discomfort
• Less maternal genital trauma
• Less anesthesia required

Forceps

• Fewer neonatal injuries (cephalohematoma, retinal hemorrhage, and transient lateral rectus palsy)
• Higher rate of successful delivery vaginally

Enhancing Healthcare Team Outcomes

Vacuum delivery is usually only done by an experienced obstetrician. However, the care of the newborn is usually by a nurse. Vacuum delivery can sometimes result in complications to the mother, including an extension of vaginal lacerations, including sphincter, and vaginal pain. In the labor and delivery room, the nurse should monitor the infant for scalp lacerations, cephalohematoma, intracranial hemorrhage, retinal hemorrhage, hyperbilirubinemia, and neurological injury. Absolute rates of complications are low; it is estimated that the rate of intracranial hemorrhage following operative vaginal delivery is at one in 650 to 850 live births. [Level 5]