Prof Tullio Ghi phD
Department of Obstetrics University of Parma
tullio.ghi@unipr.it
Ultrasound in labour: the second stage and deciding on operative
vaginal delivery
•Assessment of fetal head station and position have a key role in the correct management of labor
•Traditionally based upon vaginal examination
•These findings are of paramount importance before and during an operative vaginal delivery
•Success and complications of fetal extraction in the 2nd stage largely depend from their exact
knowledge
Background
92 years
Prerequisites for a
safe instrumental vaginal delivery
RCOG 2011
ACOG 2015
ACOG/RCOG classification of OVD
ACOG/RCOG classification of operative vaginal delivery
Outlet
Low: >+ 2 cm
Medium: 0/+1 cm High: < 0 cm
When to abandon the procedure
RCOG 2011
there are no adequate data to generate an evidence-based guideline for the number of pulls or vacuum detachments that should be allowed before abandoning the
procedure. In general, descent should be expected with traction and if there is no descent with the first several pulls, a reappraisal is necessary. ACOG 2015
RANZCOG 2016
SOGC 2015
When to abandon the procedure
Intracranial hemorrhage in singleton term fetuses and mode of delivery
California database of 583,340 nulliparous singletons deliveries 2500-4000 grms: NEJM341:1709, 1999
incidence OR
Vaginal delivery 1:1900 1,0
Elective CS 1:2750 0,7
CS in labour 1:954 2,0
Vacuum 1:860 2,7
Forceps 1:664 3,4
Failed trial of vacuum/forceps 1:334 5,7
Factors influencing the likelihood of instrumental delivery success
Aiken et al, Obstet Gynecol 2014
•3789 vacuum between 2008-2012 in UK
•Failure rate 6.5% (246/3789)
•Strongest predictors:
•>Birthweight (p<.001)
•>Length of the second stage (p<.001)
•Occiput post or trasverse (p<.05)
Predictors of Failed Operative Vaginal Delivery in a contemporary obstetric cohort
Palatnik et al, Obstet Gynecol 2016
Predictors of Failed Operative Vaginal Delivery in a contemporary obstetric cohort
Palatnik et al, Obstet Gynecol 2016
Vacuum in OA vs OP:
1. different fulcrum (“flexion point”)
Vacuum in OA vs OP:
2. different traction axis
More posterior than you think…
BJOG 2014
Fetal head position during the stage 2 of labor:
digital examination vs transabdominal US
Dupuis et al: Eur J Obstet Gynecol 2005; 123: 193–197
12
6
2
8 4
10
OA
OP
ROT ROL
IDUS: Instrumental Delivery and Ultrasound Multicentric RCT
Ramphul et al BJOG 2014
•Two large maternity units of Dublin (>6000 deliveries/year; 18%
instrumental)
•Visit vs Visit+US prior to vacuum or forceps to define head position
•257patients per arm (tot 514)
•Outcome:
•1ary: Accuracy in the diagnosis of fetal head position
•2ary: Failed instrumental vaginal delivery, neonatal or maternal injury, NICU transfer, emergency CS
IDUS: Instrumental Delivery and Ultrasound Multicentric RCT
Ramphul et al BJOG 2014
Ultrasound and fetal position
Birth simulator: Reliability of transvaginal assessment of fetal head station as defined by the ACOG classification
Dupuis et al: AJOG:(2005) 192, 868–74
Residents Attendings
Engagement 12% 12%
High mistaken for low-
mid 22.4% 15.9%
Mid mistaken for high 16% 16%
Birth simulator: Reliability of transvaginal assessment of fetal head station as defined by the ACOG classification
Dupuis et al: AJOG:(2005) 192, 868–74
Ultrasound and fetal station
Progression angle
(Barbera 2003) Progression distance
(Dietz 2005)
Midline angle
(Ghi 2009)
Head direction
(Henrich 2006)
Head-Perineum distance
(Eggebo 2006)
Head symphisis distance
(Youssef 2013)
Does transperineal ultrasound help in predicting
the outcome of vacuum extraction?
Angle of progression of the fetal head measured by transperineal ultrasound as a predictive factor
of vacuum extraction failure
Bultez et al, UOG 2016
•235 pts submitted to US prior to vacuum
•30/235 (12%) failures (>3 pop off or >20 minutes)
•OP or OT fetuses included
Am J Obstet Gynecol 2017
