Operative Vaginal Delivery

Normal Birth Mechanism

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

Indications for OVD

No indication is absolute Prolonged 2nd 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 2nd stage

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).

Four Pelvic Types

Important Landmarks

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.

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

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)

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

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

Effect of Delivery on Neonatal InjuryTowner D et al. Effect of Mode of Delivery in Nulliparous Women on Neonatal Intracranial Injury. NEJM 1999;341:1709

Delivery Death ICH Other

NSVD 1/5,000

1/1,900

1/216

C/S in Labor 1/1,250

1/952 1/71

C/S p Vac or Forceps

N/R 1/333 1/38

C/S w/o Labor 1/1,250

1/2,040

1/105

Vacuum 1/3,333

1/860 1/122

Forceps 1/2,000

1/664 1/76

Vacuum & Forceps

1/1,666

1/280 1/58

ICH – Intracranial Hemorrhage

Classification of Forceps

Williams Obstetrics - 22nd Ed. (2005)

Williams Obstetrics - 22nd Ed. (2005)

Williams Obstetrics - 22nd Ed. (2005)

Williams Obstetrics - 22nd Ed. (2005)

Williams Obstetrics - 22nd Ed. (2005)

Williams Obstetrics - 22nd Ed. (2005)