Preterm Labor Assessment: An Evidence Based Toolkit

Herman L. Hedriana, M.D.

Sac MFM Medical Group Inc.

Associate Clinical Professor in Ob/Gyn

UC Davis School of Medicine

Mary Campbell Bliss, RN, MS, CNS

Perinatal Clinical Nurse Specialist

Sutter Medical Center, Sacramento

Sources: National Center of Health Statistic, final natality data Retrieved Sept 2005 from www.marchofdimes.com/peristats.

Preterm Labor and Delivery (<37 Weeks) Preterm Labor

800,000 (1 in 5) pregnant women in US exhibit signs and symptoms of preterm labor

70% of women identified as “high risk” deliver at term

Preterm Delivery >480,000 (12.3%) preterm births in 2003 Single largest cause of perinatal mortality and

morbidity

Preterm Delivery Rates in the US 27% increase in the

past 20 years Healthy People 2010

and March of Dimes goal is to reduce the rate to 7.6% by 2010

Leading cause of neonatal morbidity and mortality

9.510.7

12.1

0

4

8

12

1982 1992 2002

Preterm Birth Rates in Multiples Multiple births increased

from 2.4% in 1992 to 3.3% in 2002

At least half of all twins and >90% of higher order multiples deliver preterm

The proportion of multiple preterm births increased 40% from 11.7% in 1992 to 16.4% in 2002

0

10

20

30

19821984

19861988

19901992

19941996

19982000

2002

Rate /1000 live births

Multiple Birth Ratios US, 1982-2002

Preterm Labor ICD-9: 644.03 Acute Disease

Specific acute treatment No effective prophylactic medication

High recurrence rate Multiple triggering factors

Previous Pregnancies & Risk of Preterm Delivery

First Second Subsequent PTD

Term 5%

Preterm 15%

Term Preterm 24%

Preterm Preterm 33%

Carr-Hill; Kristensen et al.

Diagnosis of Preterm Labor Gestational age 20-37 weeks Documented regular UC ≥6/hour

AND At least one of the following:

Rupture of membranes Cervical change Cervix 2 cm dilated or 80% effaced

National Economic Burden of Preterm Labor Hospitalization

Discharge undelivered: $360,000,000 All admissions: $820,000,000 No change in the preterm delivery rate Increasing perinatal morbidity

Nicholson et al. Obstet Gynecol 2000;96:95

What Women Know Re: Prematurity

March of Dimes survey of 600 pregnant women Not viewed as public health issue Not seen as serious problem Seen as relatively uncommon Not see themselves at risk for preterm birth Worry about their own unhealthy behaviors

Green, et al, Contemporary OB/GYN, 48(1), 2003.

What Women Know Re: Prematurity (con’t)

50% felt they knew signs/symptoms of preterm labor Amniotic fluid leaks and contractions best known Then bleeding, cramps, backache

Most call physician if experiencing preterm labor

Green, et al., Contemporary OB/GYN, 48(1), 2003

California March of Dimes Prematurity Prevention Initiative Grant to Sutter Medical Center, Sacramento Evidence based protocol for symptomatic women

To establish a uniform diagnosis of PTL To guide assessment and diagnosis of PTL To avoid unnecessary hospitalizations and

treatments To decrease use of scarce nursing/hospital

resources

California Maternity Hospitals 285 hospitals and birth centers Provide all levels of care Goal of the grant:

One standard assessment for symptomatic PTL patients

Preterm Labor Practice Assessment

Prior to development of toolkit: Collected PTL protocols from Northern CA

hospitals Developed grids with urban/rural and

NICU/no NICU groupings Analyzed for commonalities/differences Identified research articles for review

A B C D E F

DEFINITION

OF PTL

Y N N Y Y N

History Y Y N Y Y YReview of Prenatals Y Y N Y Y N

EFM Y Y Y Y Y YPO Hydration Y* N N N Y Y

MD MD Notification within 30-60' Y Y Y Y Y YIV IV Hydration* Y N N Y Y Y

R/O UTI-UA C/S* Y Y N Y Y YFetal Fibronectin* Y N N Y Y N

Vaginal Cultures (GBS)* N Y N N N NRectal Cultures (GBS)* N Y N N N N

SQ Terbutiline* Y N N Y Y YMGS04* Y-IP Y-IP Y-IP Y-IP Y-IP Y-IP

Indomethacin* Y-IP Y-IP N Y-IP N Y-IPNifedipine* Y-IP Y-IP N Y-IP N Y-IPOther RX N N N N N Y-IP

Vaginal Exam* Y N N Y Y YSterile Speculum Exam Per MD* N N N Y Y Y

Speculum Exams Per RNs* N N N Y Y YPrepare for Transport* N N N N Y N

Antenatal Steroids* Y Y Y Y Y Y* = Requires MD/HCP Orders

IP = Inpatient Orders

N N N N N N

LABS

MEDS

Ultrasound for Cervical Lengths* (Abdominal vs Transvaginal)

DX

ASSESS

Preterm Protocol Findings Consistent in some areas

Electronic fetal monitoring MD notification Review of prenatal record/patient history

Wide variation in other areas Definition of preterm labor Use of fetal fibronectin Sterile speculum exams/vaginal exams Disposition choices/criteria

Preterm Labor DiagnosisReviewed current research and relevance to

the diagnosis of preterm labor: Uterine contractions Fetal fibronectin Cervical length Initial goal: Sensitivity of the test Goal of evaluation: Specificity of the test

Labor Pain Persistent uterine contractions accompanied by

dilation and/or effacement of the cervix detected by digital examination

Gonik and Creasy AJOG 1986:154;3

Perceived contractions painful or painless but persistent

Pelvic pressure, increased vaginal discharge, backache, menstrual-like cramps

All found in term labor Poor sensitivity and specificity

Likelihood in 7-14 days

Uterine Contractions/PTD Risk 306 women with hx of PTD or 2nd trimester

bleeding 11 sites – from 1994-1996 Monitored contraction 2X/day = 39,908 hours Assessed fFN, Bishop scores, digital exams, and

cervical length Freq. of cont. higher in PM/evening hours with

increasing gestation. Iams, J.D. et al. 2002

Uterine Contractions/ PTD Risk Significant related to PTD, BUT low sensitivity

and low positive predictive value for asymptomatic women

Conclusion: Increased contractions for any individual woman is more likely to reflect advancing gestation and diurnal variation than occult preterm labor

Iams, J.D. et al. Frequency of Uterine Contractions and the Risk of Spontaneous Preterm Delivery. N Eng J Med 2002, 346:250-5.

Frequency of Uterine Contractions 4 contractions or more Low probability of

preterm birth in 7-14 days Degree of pain is

irrelevant Initiating treatment results

in unnecessary exposure to tocolytics

Hueston BJ Obstet Gynecol 1998;92:38

Iams et al NEJM 2002;346:250

Gestational Age

(weeks)Sensitivity

Positive Predictive

Value

22-24 9% 25%

27-28 28% 23%

Digital Examination 3 cm/80%/vtx/0/SROM/BRB

Best clinical sign 95% PPV in 7-14 days

Hueston BJ Obstet Gynecol 1998;92:38

Assess the structure of the external os No clinical value if cervix is < 2cm or

< 80% effaced Iams et al Obstet Gynecol 1994;84:40

Fetal Fibronectin (fFN) Protein related to cellular cohesiveness High levels at membrane-decidua interface Disruption of interface releases fFN Protein detected via immunoassay Positive test > 50 ng/ml

Amnion

Chorion

FetalFibronectin

Decidua

Fetal Fibronectin

Fetal Fibronectin vs Gestational AgeF

etal

Fib

ron

ecti

n (

ng

/mL

)

0 5 10 15 20 25 30 35 40

Gestational Age (weeks)

Clinically Relevant Time Frame

(22-35 weeks)

Source: Adapted from Garite TJ et al. Contemp Obstet Gynecol. 1996;41:77-93.

0

500

1000

1500

2000

2500

3000

3500

4000

4500

50 ng/mLCutoff Level

Clinical Value of fFN

Cervix < 3cm, <80% effaced & IBOW Sensitivity is 90% Excellent negative predictive value within 7-14

days 97 - 99% (24 – 28 weeks) 95% (>28 - <34 weeks)

Poor positive predictive value (18-20%) Iams et al AJOG 1995;173:141, Peaceman et al AJOG

1997;177:13, Leitich et al AJOG 199;180:1169

A Negative fFN Test Based on the high negative predictive

value (NPV) of fFN, decreased levels of intervention are possible: Reassurance and education for patient Ongoing prenatal surveillance Avoidance of tocolytic agents Less disruption of patient’s lifestyle

Continue care of immediate familyContinue workNormal ADLs

fFN in Clinical Care Algorithms Not for establishing diagnosis

Exclusion (NPV) is its strength Included in algorithms to exclude the likelihood of

preterm labor Must be rapidly available Commitment to act on the result by not starting

tocolytics 3 published studies demonstrating possible impact

on cost savings

fFN in Clinical Care Algorithms In a tertiary setting:

fewer admission for PTL, shorter hospital stay, less tocolytic exposure, no adverse neonatal outcome

$486,000 saved in charges Joffe et al AJOG 1999:180;581

In community hospital setting: no benefit in > 3 cm cervical dilation; 90% reduction of

transfers to tertiary facility Giles et al AJOG 2000:182;439

Savings do not show in cost analysis models in a large teaching facility (Bethesda)

Sullivan et al JMFM 2001:10;1

Length of Cervix and the Risk of Preterm Delivery @ 24 wksCx (mm) RR

5 52

10 9.1

15 2.7

20 1.2

25 0.7

30 0.5

40 0.5

Reliability of Cervical Length Consistent images in more

than 95% of patients regardless of habitus and order of multiples

Strict adherence to criteria

Superior Positive Predictive Value (PPV) to digital exam

Cervical length of 30 mm or more have very high Negative Predictive Value

Combining Cervical Length and Fetal Fibronectin Improves accuracy of diagnosis

Goldenberg et al AJPH 1998:88;233, Rizzo et al AJOG 1996:175;1146

In diagnosis, combined is not superior to either one alone.

Rozenberg et al AJOG 1997:176;196

Strength consistently with exclusion Goldenberg et al AJPH 1998:88;233

Toolkit Definition of Preterm Labor

Persistent uterine contractions Objective documentation of cervical

change Dilated to > 2 cm or 80% effaced Positive biochemical marker

Preterm Labor Taskforce Consensus Decisions Labor is consistent contractions with

cervical change Rapid fFN chosen as screening test for

preterm labor in symptomatic patients Transvaginal ultrasound for cervical length

is used as an adjunct of fFN Decision to admit, discharge, transport to

be made within 4 hours

PTL Assessment Toolkit Contents PTL Care/Disposition Protocol/Algorithm PTL Assessment Pre-Printed Orders PTL Home Care Instructions PTL Patient Education Procedures (Speculum, GBS, Ferning) Competencies PTL Power Point Presentations

Preterm Labor Care/Disposition Protocol Confidence that uterine contractions alone

DO NOT mean labor Contains a logical sequence of events Disposes of clinical concerns Should allow for a decision within 4 hours

of admission

Evaluation of Symptomatic Preterm Labor

Review of history Fetal heart and contraction monitoring Cervical examination - look for best clinical

sign Severity of symptoms bears very little to

clinical significance Do not initiate tocolytics unless FFN and/or

cervical length is assessed

SYMPTOMATIC WOMEN20-37 WEEKS GESTATION

EFM

PSYCHO-SOCIALASSESSMENT

MEDICAL ASSESSMENT

HISTORY

SUPPORTIVE DATA

PHYSICAL ASSESSMENT

PRETERM LABOR ASSESSMENT

PRETERM LABORSUPPORTIVE CARE

NOTIFY PHYSICIAN

TESTS ORDERED

UA RESULTS

RISK ASSESSMENTFLANK PAINSEXUAL INTERCOURSEDEHYDRATION

FETAL ASSESSMENT

MEMBRANE STATUS

POSITIONINGHYDRATIONPO OR IV

LABSULTRASOUND

STERILE SPECULUM EXAM

GROUP B STREP CULTUREFETAL FIBRONECTIN

STERILE VAGINAL EXAM

CERVICAL STATUS ASSESSMENT

COMPONENTS OF PTL ASSESSMENT ALGORITHM

Preterm Labor Assessment Pre-Printed Physician Order Set Concise MD order set Rules out specific pathology Sterile speculum exam for fFN EFM monitoring for fetal

wellbeing

Homecare Instructions Bedrest not effective Minimally restrictive Effective follow-up important

Telephone calls Frequent office visits

Preterm Labor Patient Education “Street-smart” patients/clients Stay with the facts….decrease

confusion Information is readily accessible

Friendly, easy reading Warning signs to contact provider

Capping Off the Toolkit Sterile Speculum procedure GBS Procedure Nursing Competencies

Sterile speculum exam Fern testing

PTL Assessment Reference List

Preterm Labor Assessment Toolkit A great opportunity to :

Standardize preterm labor assessment/disposition

Maintain maternal/fetal safety Promote patient satisfaction

ANY QUESTIONS??? Contact Mary Campbell Bliss at (916)

733-8471 or Blissm@sutterhealth.org