Vacuum-Assisted Vaginal Delivery: Protocols for Length and Number of Pulls
Vacuum-assisted vaginal delivery (VAVD) should be limited to no more than three cup detachments and no more than four traction attempts to minimize maternal and neonatal complications. 1
Technique and Protocol Guidelines
Cup Placement and Preparation
- The cup should be placed on the flexion point of the fetal head, approximately 3 cm anterior to the posterior fontanelle, to promote proper flexion and descent 2, 3
- Proper cup placement is essential for successful vacuum delivery and minimizing complications 2
- The vacuum pressure should be increased gradually to the recommended level (typically 450-600 mmHg depending on device) 3
Number of Pulls and Duration
- Maximum of four traction attempts should be performed 1
- No more than three cup detachments/reapplications should be attempted 1
- Each traction should be coordinated with maternal pushing efforts and uterine contractions 3
- The procedure should be abandoned if no descent is observed after three proper pulls 3, 4
- The entire procedure should be completed within 15-30 minutes of initial cup application 3
Proper Technique
- Traction should be applied perpendicular to the cup in the direction of the pelvic axis 3
- The operator's non-dominant hand should follow the descent of the fetal head while applying traction with the dominant hand 3
- "Rocking" movements should be avoided as they increase the risk of cup detachment and scalp injuries 2
- Episiotomy should be considered based on perineal assessment, not performed routinely 3
Indications for Abandoning the Procedure
- Failure to achieve proper cup placement 2
- No descent after three properly applied tractions 3
- Three pop-offs (cup detachments) 1
- Total procedure time exceeding 30 minutes 3
- Evidence of fetal scalp trauma or excessive caput formation 3
Factors Associated with Failed Vacuum Delivery
- Increasing gestational age (OR 1.2 per week) 4
- Estimated fetal weight ≥3750g (OR 5.7 compared to <3250g) 4
- Occiput posterior position (OR 2.6) 4
- Higher station of fetal head (less descent) 4
- Epidural analgesia (OR 3.0) 4
- Maternal height (OR 0.97 per cm - shorter women have higher risk) 4
- Failure to progress as indication for vacuum attempt (OR 1.7) 4
Safety Considerations
- Vacuum extraction is associated with higher rates of retinal hemorrhage (38%) compared to forceps (17%), though the clinical significance is uncertain 5
- Proper documentation using a checklist for vacuum delivery has been shown to reduce severe perineal lacerations (OR 0.4,95% CI 0.18-0.89) 1
- Continuous electronic fetal heart rate monitoring is recommended during operative vaginal delivery 6
- The lateral decubitus position for the mother can help attenuate hemodynamic impact of uterine contractions 6
Contraindications
- Gestational age <34 weeks (due to increased risk of fetal intracranial hemorrhage) 3
- Fetal coagulation disorders 3
- Fetal demineralization conditions (osteogenesis imperfecta) 3
- Non-cephalic presentation 3
- Unengaged fetal head 3
- Suspected cephalopelvic disproportion 6
Alternative Approaches
- Consider forceps delivery if vacuum extraction fails but vaginal delivery remains feasible 5
- Sequential use of instruments (vacuum followed by forceps or vice versa) may be considered in select cases, though with potentially increased risk 5
- Cesarean delivery should be performed if operative vaginal delivery fails or is contraindicated 4
Following these protocols for vacuum-assisted vaginal delivery helps ensure maternal and neonatal safety while maximizing the chances of successful delivery.