Transcript Operative Vaginal Delivery

Operative Vaginal Delivery
Normal Birth Mechanism
Introduction
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US incidence of Operative Vaginal
Delivery (OVD) – 4.5%*
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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
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Nulliparous: lack of continuous progress
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Multiparous: lack of continuous progress
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>3hrs with regional anesthesia
>2hrs w/o regional anesthesia
>2hrs with regional anesthesia
>1hr w/o regional anesthesia
Fetal compromise
Maternal benefit to shortened 2nd stage
Station
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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
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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
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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
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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
*ACOG Practice Bulletin #17 (June 2000)
**Johnson RB. The Cochrane Library Issue 4, 1999
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“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:
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Less maternal trauma
Less need for general and regional anesthesia
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
Delivery
NSVD
C/S in Labor
C/S p Vac or
Forceps
C/S w/o Labor
Vacuum
Forceps
Vacuum &
ICH – Intracranial
Hemorrhage Forceps
Death
ICH
Other
1/5,000 1/1,900 1/216
1/1,250 1/952
1/71
N/R
1/333
1/38
1/1,250 1/2,040
1/3,333 1/860
1/2,000 1/664
1/1,666 1/280
1/105
1/122
1/76
1/58
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)