1. Operative Vaginal Delivery

2. Normal Birth Mechanism

3. Introduction US incidence of Operative Vaginal Delivery (OVD) – 4.5%* Overall rate of OVD declining, but the proportion of vacuum deliveries is 4-times the rate of forceps Forceps deliveries = 0.8% of vaginal births Vacuum deliveries = 3.7% of vaginal births UpToDate: September 2010

4. Indications for OVD No indication is absolute Prolonged 2 nd stage Nulliparous: lack of continuous progress >3hrs with regional anesthesia >2hrs w/o regional anesthesia Multiparous: lack of continuous progress >2hrs with regional anesthesia >1hr w/o regional anesthesia Fetal compromise Maternal benefit to shortened 2 nd stage

5. Station At the 0 station, the fetal head is at the bony ischial spines and fills the maternal sacrum. Positions above the ischial spines are referred to as -1 through -5 As the head descends past the ischial spines, the stations are referred to as +1 through +5 (head visible at the introitus).

6. Four Pelvic Types

7. Important Landmarks

8. Fetal attitude & lateral flexion of the fetal head A: Synclitism—The plane of the biparietal diameter is parallel to the plane of the inlet B: Asynclitism—Lateral flexion of the fetal head leads to anterior parietal or posterior parietal presentation.

9. Prerequisites for OVD Informed consent Vertex Engaged ≥34 weeks (vacuum delivery) Fully dilated Membranes ruptured Adequate maternal pelvis Adequate anesthesia Maternal empty bladder Backup plan Ongoing fetal and maternal assessment

10. Contraindication-OVD Non-cephalic, face or brow presentation Unengaged vertex Incompletely dilated cervix Clinical evidence of CPD < 34 weeks gestation (vacuum) Need for device rotation (vacuum) Deflexed attitude of fetal head Fetal conditions (e.g. thrombocytopenia)

11. Classification of OVD Outlet Scalp visible @ introitus w/o separating labia Fetal skull @ pelvic floor Saggital suture in AP plane (or ROA/LOA) Fetal head at or on perineum Rotation < 45 degrees Low Leading point of fetal skull > or = +2 station Rotation < 45 degrees Rotation > 45 degrees Mid Station above +2 station but the head is engaged High Not included in classification

12. Vacuum versus Forceps “Selection of the appropriate instrument and decisions about the maternal and fetal consequences should be based on clinical findings at the time of delivery.” A meta-analysis comparing vacuum extraction to forceps delivery showed that vacuum extraction was associated with significantly: Less maternal trauma Less need for general and regional anesthesia *ACOG Practice Bulletin #17 (June 2000) **Johnson RB. The Cochrane Library Issue 4, 1999

13. Effect of Delivery on Neonatal Injury Towner D et al. Effect of Mode of Delivery in Nulliparous Women on Neonatal Intracranial Injury. NEJM 1999;341:1709 DeliveryDeathICHOther NSVD1/5,0001/1,9001/216 C/S in Labor1/1,2501/9521/71 C/S p Vac or Forceps N/R1/3331/38 C/S w/o Labor1/1,2501/2,0401/105 Vacuum1/3,3331/8601/122 Forceps1/2,0001/6641/76 Vacuum & Forceps 1/1,6661/2801/58 ICH – Intracranial Hemorrhage

14. Classification of Forceps

15. Williams Obstetrics - 22nd Ed. (2005)