ecograﬁain periodo(espulsivo( - tes eventi ·...

Bologna, 23 Novembre 2013

Ecografia in periodo espulsivo

[email protected] University of Bologna


• PredicAon of vaginal delivery in the second stage of labor is tradiAonally based upon progression of fetal head descent • Arrest of labor is diagnosed in case of poor progression • Obstetric intervenAon is needed (CS or instrumental vaginal delivery) • First indicaAon to primary caesarean in USA

Background


Reassessing the labor curve in nulliparous Zhang et al, Am J Ob Gyn 2002

Volume 187, Number 4 Zhang, Troendle, and Yancey 825Am J Obstet Gynecol

we systematically selected 1329 subjects from 1992 to1996 on the basis of the following inclusion criteria: nul-liparous, singleton pregnancy, maternal age between 18and 34 years, gestational age between 37 weeks 0 days and41 weeks 6 days, birth weight between 2500 and 4000 g,spontaneous onset of labor, vertex presentation at admis-sion, cervical dilation <7 cm at admission, and durationof labor from admission to delivery >3 hours. Because thepurpose of our study was to demonstrate that a substan-tial proportion of labor ended in vaginal delivery mayprogress slower than the current cutoff points for laborarrest, we excluded the cesarean deliveries (n = 167),leaving 1162 subjects for analysis.

Resident physicians provided the majority of labor anddelivery services under supervision of attending physi-cians. Forceps and vacuum were primarily used as lowand outlet procedures with fewer than 1% of proceduresdone at the midpelvic level. The choice of delivering in-struments was made by the delivering physician. All lowoperative procedures required a maternal or fetal indica-tion, whereas outlet procedures were occasionally doneelectively at the discretion of the supervising physician.There was no active management of labor or other spe-cial protocols.

In addition to demographic characteristics, admissionassessment and summary of labor and delivery, time ateach vaginal examination, cervical dilation and station ateach examination were extracted from the labor charts.Cervical dilation was measured in centimeters (from 0 to10 cm), whereas the station of fetal presenting part wasrecorded in thirds (from –3 to +3 above or below the ischial spines).

Two major statistical analyses were conducted. First, weexamined the pattern of labor progression by looking atthe relationship between duration of labor and cervicaldilation. A repeated-measures regression with a polyno-mial function was used to model the curve of cervical di-lation.9 Because patients were admitted at various pointsof cervical dilation but all ended at 10 cm, the regressionwas carried out in a reverse approach, with the 10 cm asthe starting point and going backward. A 10th-order poly-nomial in time fitted the dilation values the best. PROCMIXED of SAS was used (SAS Institute, Cary, NC).

Second, we examined the time interval of cervical dila-tion from 1 centimeter to the next (eg, from 4 cm to 5

Fig 1. Comparison between the Friedman curve and the patternof cervical dilation based on the current data.

Fig 2. Patterns of cervical dilation (left) and fetal descent (right) innulliparous women.

Table I. Comparison of study populations between Fried-man’s study and the current study

Friedman Current study study

(n = 500) (n = 1162)

Year of data collection Early 1950s 1992-1996Birth weight between 2500-4000 g (%) 85 100Labor induction (%) 4 0Caudal/epidural anesthesia (%) 8 48Oxytocin augmentation (%) 9 50Breech delivery and twin gestation(%) 4 0Low forceps/vacuum (%) 51 13Mid forceps or cesarean delivery (%) 6 0

Table II. Expected time interval and rate of change ateach stage of cervical dilation

Cervical Timedilation interval

(cm) (h)*

From To Rate of cervical dilation (cm/h)*

2 3 3.2 (0.6, 15.0) 0.3 (0.1, 1.8)3 4 2.7 (0.6, 10.1) 0.4 (0.1, 1.8)4 5 1.7 (0.4, 6.6) 0.6 (0.2, 2.8)5 6 0.8 (0.2, 3.1) 1.2 (0.3, 5.0)6 7 0.6 (0.2, 2.2) 1.7 (0.5, 6.3)7 8 0.5 (0.1, 1.5) 2.2 (0.7, 7.1)8 9 0.4 (0.1, 1.3) 2.4 (0.8, 7.7)9 10 0.4 (0.1, 1.4) 2.4 (0.7, 8.3)

*Median (5th and 95th percentiles).


• Extreme variability in the clinical definiAon of dystocia • In the second stage, different criteria according to parity or epidural (1-‐3 hours) • ̀ If progress is made the duraAon alone does not mandate delivery’

Criteria for labor arrest (ACOG bulleAn 2003)


• RetrospecAve study of 17659 nulliparous • 79% delivery <2h vs 21% >2h (1251 >4h!) • The longer stage 2: the higher the risk of PPH, endometriAs, perineal laceraAons, Apgar <5

How long is too long: the duraAon of stage 2 and labor outcome

Cheng, Am J Ob Gyn 2004

pregnancies had a second stage of labor that progressedO4 hours. Various maternal, fetal, and labor character-istics are reported in Table I.

Mode of delivery

We examined mode of delivery as a function of timeduring the second stage of labor. Figure 1 depicts thepercentage of subjects who underwent unassisted vagi-nal, operative vaginal, or cesarean delivery. Rates of ce-sarean delivery increased sharply as the second stage oflabor progressed O3 hours. When the second stage las-ted O4 hours, the cesarean delivery rate peaked at32.8%. Similarly, rates of vaginal delivery declined rap-idly from O80.0% in the 1- to 2-hour interval to 56.6%when the second stage ended during the 2- to 3-hour in-terval. It further declined to 18.8% when the secondstage was prolonged O4 hours. In contrast, the rate ofoperative vaginal delivery increased with time, ap-proaching 50% after a second stage of O4 hours.

When controlling for maternal age, ethnicity, weight,gestational age at delivery, year of delivery, length of thefirst stage of labor, use of epidural anesthesia, fetal occi-put posterior position, and birth weight, we found thatthe duration of the second stage remained a significantfactor that influenced the mode of delivery. When thecompleted hours of the second stage were examined,there was an increase in the rate of cesarean delivery thatwas associated with increasing time (Table II). WhenO3 hours of the length of the second stage of laborwas compared to !3 hours, there was a dramatic in-crease (odds ratio, 5.84; P !.001) in the rate of cesarean

delivery. This difference persisted when a comparisonwas made toO4 hours of second stage to!4 hours (Ta-ble II). Among those patients who underwent a vaginaldelivery, the rate of operative vaginal deliveries exhibi-ted similar trends, with increases seen throughout thesecond stage of labor (Table II).

Maternal outcomes

The maternal complications of postpartum hemorrhage,third- or fourth-degree perineal laceration, chorioamnio-nitis, and endomyometritis that are associated with eachinterval of second stage of labor were examined, and theresults are shown in Figure 2. The frequency of postpar-tum hemorrhage increased from 7.1% during the 0- to 1-hour interval of second stage to 30.9% when secondstage progressedO4 hours. A similar trend was observedfor the rates of third- and fourth-degree perineal lacera-tions: 11.6% during the 0- to 1-hour interval and 34.2%with O4 hours of second stage. Likewise, the incidenceof both chorioamnionitis and endomyometritis increasedwith a prolonged second stage: chorioamnionitis, from2.4% during the 0- to 1-hour interval to 19.6% withO4 hours; and endomyometritis, 1.1% to 6.6%.

When potential confounders were controlled for withmultivariate logistic regression, the relationship betweenthe rates of chorioamnionitis and the lengthening timeintervals of the second stage remained statistically signif-icant. The association, however, was not statistically sig-nificant for endomyometritis after an adjustment forconfounders (Table II). The risk for extensive perineallaceration as the second stage progressed to O4 hoursand the risk for postpartum hemorrhage when secondstage lasted O3 hours remained statistically significantwhen being controlled for confounders, which includedoperative vaginal delivery, episiotomy, birth weight,and fetal position.

Figure 1 The mode of delivery (n = 15,759) was reportedby the duration of the second stage of labor.

Figure 2 Maternal outcomes reported by duration of thesecond stage of labor. The closed squares represent third- orfourth-degree lacerations; the closed pyramids represent post-partum hemorrhage; the closed diamonds represent chorioam-nionitis; the closed circles represent endomyometritis.

Cheng, Hopkins, and Caughey 935


When to stop pushing: Le Ray, Am J Ob Gyn 2009

in the context of continuous fetal sur-veillance in the second stage of labor, aprolonged duration of the active secondstage does not increase the risk of adverseneonatal outcome.

There are few previous publicationsthat specifically have addressed the im-pact of the duration of expulsive effortson the fetal and neonatal well-being.11-14

These studies had a small sample size andwere focused on biologic outcomes (pHand lactates). In our study, the popula-tion is large and homogenous (nullipa-rous women with uncomplicated preg-nancies at term with epidural analgesia)and is derived from a multicenter trialcohort. The collection of data was pro-spective and rigorous, especially with re-spect to the hours of pushing, with miss-ing data for only 4 subjects. We classifiedpushing duration into 4 classes and dem-onstrated an increased risk for intrapar-tum fever and PPH. In previous studieson this topic, some authors have over-simplified categorization of the secondstage (!2 and "2 hours), which limitsinterpretation of their results.1,4,5,7 Neo-natal outcomes were also collected pro-spectively to analyze accurately the neo-natal health status. This reinforces thevalidity of our results.

Previous studies concerning pro-longed second stage of labor did not dif-ferentiate passive and active phases; thus,we cannot compare our results to thosefrom other studies.1-7 However, in ac-

cordance with these studies, after adjust-ment of data, we did not find an associ-ation between duration of pushing andadverse neonatal outcomes.

In 1973, Wood et al11 showed, among29 patients, that neonatal arterial pH de-creased to 0.003 units for every minute ofpushing. Other authors found similar re-sults in small biologic studies.12,14 In ourstudy with a large sample size, in whichthere was routine fetal intrapartum sur-veillance with fetal heart monitoring, wefound no correlation between neonatalarterial pH values and the duration of ex-pulsive efforts. Moreover, we found asurprising, but not significant, decreasein the rate of arterial pH !7.10 after 2hours of pushing. This result may reflecta “healthy worker” effect (ie, that themost fragile infants were probably bornduring the first 2 hours of pushing, ifneeded, by instrumental vaginal deliveryor by cesarean delivery). But this resultmay also reflect a context of careful ob-stetric management and an adequate fe-tal surveillance during the active secondstage of labor, by the performance of anoperative delivery when severe fetal heartrate abnormalities occurred. Onlywomen with normal fetal heart monitor-ing were allowed to continue pushing af-ter 2 hours.

Because this was a secondary analysisof a randomized trial that was not de-signed specifically to answer the studyquestion, our study had several limita-

tions. We had only short-term data con-cerning maternal morbidity indicators.The effect of prolonged expulsive effortson pelvic floor and continence was notassessed. Moreover, data were collectedfrom 1994-1996. Probably, obstetricpractices have changed since this period;there might be fewer midpelvic extrac-tions, fewer rotational procedures, andmore caesarean deliveries during the sec-ond stage. The operative vaginal deliveryrate was high in this trial, like in othertrials that compared delayed and imme-diate pushing.10 Thus, a selection biascannot be excluded. In our population,most women were white or Asian. Inlight of the different prevalence of pelvicconfigurations in different ethnicgroups, our results might not be gener-alized to ethnic groups that were underrepresented in our study. Moreover, ourresults cannot be generalized to multip-arous and nulliparous women who didnot have epidural analgesia. Finally, be-cause the exact duration of the first stageof labor is difficult to estimate accurately,we did not adjust for it. First-stage dura-tion might have an influence on mater-nal and neonatal outcomes.

Sung et al15 found that a second stageof labor of "4 hours was associated withan increase in unintentional hysterot-omy extensions at cesarean delivery andprolonged operative time. In the PEO-PLE trial, there were no data about ad-verse events that occurred during cesar-

TABLE 3Maternal and neonatal morbidity indicators according to each pushing duration category

Indicator<1 h(n ! 635)

1–2 h(n ! 605)

2–3 h(n ! 374)

>3 h(n ! 244) P valuea

Postpartum hemorrhage, n (%) 53 (8.4) 75 (12.7) 70 (19.5) 64 (31.1) ! .001................................................................................................................................................................................................................................................................................................................................................................................

Third- to 4th-degree perinealtear, n (%)

98 (6.0) 47 (7.8) 52 (13.9) 38 (15.7) ! .001

................................................................................................................................................................................................................................................................................................................................................................................

Intrapartum fever, n (%) 21 (3.3) 38 (6.3) 33 (8.8) 30 (12.3) ! .001................................................................................................................................................................................................................................................................................................................................................................................

Arterial pH (mean # SD) 7.25 # 0.07 7.24 # 0.087 7.25 # 0.07 7.26 # 0.07 .009................................................................................................................................................................................................................................................................................................................................................................................

Arterial pH !7.10, n (%) 18 (3.6) 25 (5.2) 5 (1.7) 3 (1.4) .020................................................................................................................................................................................................................................................................................................................................................................................

5 min Apgar score !7, n (n%) 5 (0.8) 8 (1.3) 3 (0.8) 4 (1.6) .566................................................................................................................................................................................................................................................................................................................................................................................

Neonatal trauma, n (%) 34 (5.4) 41 (6.8) 42 (11.2) 30 (12.3) ! .001................................................................................................................................................................................................................................................................................................................................................................................

Admission in neonatalintensive care unit, n (%)

22 (3.5) 25 (4.1) 26 (7.0) 21 (8.6) .004

................................................................................................................................................................................................................................................................................................................................................................................a "2 test with 3 degrees of freedom.

Le Ray. Expulsion efforts in nulliparous women with epidural analgesia. Am J Obstet Gynecol 2009.

www.AJOG.org Obstetrics Research

OCTOBER 2009 American Journal of Obstetrics & Gynecology 361.e5


In caso di intervento ostetrico nel 2° stadio

• Essenziale la determinazione esafa della stazione e della posizione della testa fetale • Il correfo rilievo di quesA parametri consente di scegliere tra TC o vacuum • Valutazione clinica e’ complessa e richiede grande esperienza • Tumore da parto e rimodellamento cranio!


Clinical assessement of fetal staAon

Ischial spines

-‐ 5 cm

+ 5 cm

0

Bologna, 23 Novembre 2013 Head rotaAon as a measure of fetal staAon

Ischial spine


ACOG classificazione del parto operaAvo

Uscita

Basso: >+ 2 cm

Medio: 0/+1 cm Alto: < 0 cm


Birth simulator: Reliability of transvaginal assessment of fetal head staAon as defined by the ACOG classificaAon

Dupuis et al: AJOG:(2005) 192, 868–74


Birth simulator: Afendibilità della valutazione clinica

Dupuis et al: AJOG:(2005) 192, 868–74

Residents Afendings

Engagement 12% 12%

High mistaken for low-‐mid 22.4% 15.9%

Mid mistaken for high 16% 16%


Fetal head posiAon during the 2nd stage of labor: digital examinaAon vs transabdominal US

Dupuis et al: Eur J Obstet Gynecol 2005; 123: 193–197


Intracranial hemorrage 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 ElecAve 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


• Ultrasound have been suggested as an addiAonal tool for the physician in the management of labor • Used mainly in the research context • Sonographic assessment of fetal head staAon and posiAon in stage 2 has proved to be reproducible and accurate • The possible use of ultrasound in predicAng vaginal delivery is under invesAgaAon

Ultrasound in the 2nd stage of labor


How reliable is transperineal US in assessing fetal occiput posiAon during the the 2nd stage

Ghi et al, ISUOG Sidney 2013

!

Right OA

!

Right OP

Occiput posiAon diagnosed by TP US confirmed at suprapubic US in 52/52 cases


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)


Progression angle and staAon: MRI Bamberg et al, UOG June 2011


Linea infrabubica

≤ +1 cms

44/57 o 77%

Range +1/ +2

51/59 o 86%

≥+3 cms

46/52 o 88%

< 90° 90° > 90°

US of fetal head direcAon and digital examinaAons (Ghi et al: Ultrasound Obstet Gynecol 2009; 33: 331–336)


p <.0001

CorrelaAon between sonography of fetal head direcAon and digital examinaAons (Ghi et al: Ultrasound Obstet Gynecol 2009; 33: 331–336)

Bologna, 23 Novembre 2013 Comparison between ultrasound parameters and clinical examinaAon to assess fetal head

staAon in labor Tutschek et al, UOG 2013


>200°

< 135°

Progression angle Barbera et al, UOG March 2009 (II)

• Single assessment in the second stage • All vaginal delivery if angle >120° (82/88)


A study of progress of labor using intrapartum translabial US Tutschek et al, BJOG 2011


Sonographic changes during stage 2 and predicAon of vaginal delivery

•  low-‐risk nulliparous women at the beginning of the acAve stage 2

•  3D intrapartum translabial ultrasound every 20 min by an operator blinded to the clinical examinaAon (T1, T2, T3, T4…)

•  All volumes subsequently analyzed offline by an operator blinded to the labor outcome (spontaneous Vaginal Delivery vs TC or vacuum)

•  Different parameters measured


Sonographic changes during stage 2 and mode of delivery Ghi et al (UOG april 2013)

110

120

130

140

150

160

170

T1 T2 T3 T4 T5 T6 10 15 20 25 30 35 40 45 50

T1 T2 T3 T4 T5 T6


Sonographic changes during stage 2 and Ame to delivery

Maroni et al (UOG submifed)

100

110

120

130

140

150

160

170

AP1 AP2 AP3 AP4 AP5 AP6

del < 60 min

del > 60 min


Angle of progression T1 and Ame to delivery Maroni et al (UOG submifed)

<120°

>150°


Assessment of the head staAon Trafato Ostetricia 1972 from BerAno and Clivio

I.  Pelvic Inlet with mobile head:

The finger may reach the superior margin of the pubic symphysis

II.  Pelvic Inlet with fixed head The finger may reach the midpoint of the pubic symphysis

III. Midpelvis The finger may only reach the inferior margin of the pubic symphyisis


From BerAno and Clivio 1972 Head-‐Symphisis distance (HSD)

Youssef et al (UOG april 2013)

From fingers to ultrasound: Head-‐symphysis distance (HSD)


-3 0 +2

HSD

HSD: a simple and reliable index of fetal head staAon in labor Youssef et al (UOG april 2013)


HSD changes during stage 2 and mode of delivery

Youssef et al (Acta Obst Gyn Scand submifed)

vacuum or CS

Spontaneous vaginal delivery

AUC 0.879±0.071

T2

Cut off>14 mm • SensiAvity 90.0% (9/10 oper deliv) • VPP 73.8% (31/42 oper deliv)


Ultrasound in labor: a caregiver’s perspecAve

Youssef et al Lefer to the Editor (UOG april 2013)

A survey of 264 italian obstetricians afending an ultrasound course

Sonographic measurements with angles (i.e. angle of progression) and 3D ultrasound are felt as obstacles


• Intrapartum ultrasound may prove useful in predicAng spontaneous vaginal delivery • Longitudinal changes more accurate than single assessment and may be of help in rouAne seung for prolonged stage 2 • Straight measurements (HSD) are easier and more reproducible

Conclusions

…thank you!!

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