Preterm Labour

Preterm Labour

1. PROF. ABOUBAKR ELNASHAR

BENHA UNIVERSITY HOSPITAL, EGYPT
[email protected]

Preterm Labour
Aboubakr Elnashar

2. Introduction
Definition
Incidence
Neonatal outcome
Aetiology
Risk factors


Management of
asymptomatic high-risk
women
Before pregnancy
During pregnancy
Prevention
Prediction

Management of
symptomatic women
Assessment
Therapy


Contents
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3. INTRODUCTION
Definition
Incidence
Neonatal outcome
Aetiology
Risk factors

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4. DEFINITION

Deliveries between 24+0 and 36+6 w.
Documented regular UC ≥6/h
AND
At least one of the following:
Rupture of membranes
Cervical change
(Cervix 2 cm dilated or 80% effaced)

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5. Clinical subtypes
1. Indicated: 1/3
for maternal or fetal reasons
2. Spontaneous: 2/3
PTL
PPROM

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6. Subcategories:
1. mildly preterm:
32+0 to 36+6 w (incidence 55%)
2. moderately preterm:
28+0 to 31+6 w (incidence 0.7%)
3. extremely preterm:
24+0 to 27+6 w (incidence 0.4%).

24--Extreme--28--Moderate—32--Mild--37


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7. Incidence
5 -18%
UK: 6.6%
USA: 12%
{differing aetiological, socioeconomic and cultural
factors}.

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8. NEONATAL OUTCOMES


Mortality:
leading cause of newborn deaths (WHO, 2012)
2
nd
leading cause of death (after pneumonia) in
children under 5 y.





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9. Morbidity
1. Neuro developmental impairment, disability and
handicap: especially within the 24-26-w
50% of the survivors at 23-25 w were impaired, half
with severe disability.
2. Educational difficulties.
3. Social behaviour and criminality, as well as
subsequent influences on adult health.

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10. AETIOLOGY
I. Infection
Subclinical infection of the choriodecidual space
and amniotic fluid

II. Vascular
1. Spontaneous prematurity has been associated
with an increase in membrane haemosiderin
deposits, thought to reflect decidual haemorrhages.
2. The link between placental abruption and either
uterine activity or PPROM is well recognized.


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11. III. Uterine overdistension

1. Multiple pregnancy
Median gestation at delivery
for twins: 35 w
for triplets 33 w.
ART responsible for
35% of twin
77% of triplets

2. Polyhydramnios
Fetal anomalies
Atresias of the GIT, are the most common cause of
polyhydramnios: PTL.


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12. IV. Cervical incompetence
Difficult diagnosis
Even a careful review of the clinical events: PTL
does not necessarily show correlation with the
aetiology.

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13. V. Intercurrent illness

1. Serious infection:
Pyelonephritis, appendicitis and pneumonia
{direct blood-borne spread of infection to the uterine
cavity or
indirectly to chemical triggers, such as endotoxins
or cytokines}.
2. Other medical complications
cholestasis of pregnancy
3. Any surgical procedures
{mechanisms remain obscure.}

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14. Often multifactorial
No risk factors in 50%
PTL is a “syndrome”
•Inflammation/Infection (40%)
•Maternal/fetal stress (25%)
•Uteroplacental ischemia (25%)
•Thrombophilia, decidual hemorrhage, abruption
•Abnormal uterine distension (10%)
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15. RISK GROUPS

I.Major risk factors

1.Previous PTL.
After 1 PTL: risk 20%.
After 2 PTL: risk 40%

2· Uterine overdistension.
Multiple pregnancies
Polyhydramnios
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16. 3. Uterine abnormalities.
Cone biopsy
LLETZ.
Surgical cervical dilatation



4. Malformed uterus
{cervical weakness},
although recent evidence suggests that
abnormalities of uterine vascularity may also playa
role.

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17. 5. Fibroids
Controversial
considering their frequency, their influence is
probably minimal in the absence of cervical
involvement.

6. Factors in current pregnancy.
intercurrent illness
Surgery
recurrent vaginal bleeding.

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18. II. Minor risk factors
A. Modifiable.
Smoking
low BMI
interpregnancy interval <1y.

B. Not modified
Maternal age (teenage)
Parity (nulliparous or grandmultiparous)
Ethnicity (black women)
Socioeconomic deprivation
Unemployment
low levels of education.
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19. MANAGEMENT OF ASYMPTOMATIC
HIGH-RISK WOMEN
Before pregnancy
During pregnancy
Prevention
Prediction


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20. I. Before pregnancy
1. Assessment and the events leading to their PTL
reviewed.
2. Management Plan for any subsequent
pregnancy
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21. II. During pregnancy
A. Prediction
1. Assessment of risk factors
2. Early dating scan
3. TVS: cervical length & dilatation
4. Foetal fibronectin in cervicovaginal secretions
5. Salivary oestriol, home uterine-activity monitoring and measurement of
plasma metabolites: not effective in routine clinical practice

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22. 1. Assessment of risk factors:

Scoring systems e.g. Creasy score

Based on risk factors e.g.
Previous PTD
Bleeding in pregnancy,
UTI
Higher order pregnancies
BMI< 20 kg/m
2
,
Stress (family illness, mortality, disruption, violence, or financial)

Do not identify the majority of women Limited
clinical use. have not proved helpful.

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23. 2. Early dating scan
{To time subsequent investigations.
Ensures precise gestational age}

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24. 3. Cervical ultrasound
The risk of PTL is inversely related to cervical length
[C}
Not TAS:
{full bladder: false lengthening and can obliterate
gross funneling}.
TVS: more accurate than digital measurements
In asymptomatic women
11-20 mm: 4% risk
10 mm: 15% risk
<10 mm: dramatic increase in risk
Recommended
high risk asymptomatic at 22-24 w
Not for routine screening

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25. 4. Cervlcovaginal fibronectin testing
Done after 23 w {high prior to this gestation, rarely present in vaginal
secretions between 23 and 34 w}.
fFN: glue-like ‘ protein binding the choriodecidual membranes.
Any disruption at the choriodecidual interface: fFN release
positive/ negative result.

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26. Steps:
No Digital examination or lubricating jelly or Endocervical swabbing
The swab should be rotated in the posterior fornix for 15-20 secs
The test result should be read within 15 min

False-positive results
Sexual intercourse within 24 h.
Vaginal bleeding.

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27. Interpretation
Positive at 24 w: 46% will deliver before 30 w: no proven treatment: several
groups are studying the potential role of antibiotics.

Negative: risk of PTL 1%: High negative predictive value to either withhold
treatments or optimize their timing.


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28. B. Prevention

Before pregnancy:
1. Smoking cessation.
2. Dietician referral for women with a low BM.
4. Prevent multiple pregnancy
5. Leaving 12 months between pregnancies

During pregnancy
1.Detection and tt of vaginal and intra­uterine
infection
2. Cervical cerclage
3.Progesterone
4.Life style modification

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29. 1. Diagnosis and treatment of vaginal and
intra­uterine infection
a. Bacterial vaginosis
{associated with an increased risk of PTL}
Diagnosis:
A vaginal swab is rolled on to a glass slide
Gram staining and microscopy: Nugent scoring.
Treatment:
Oral metronidazole: 5-7 days at standard doses
lowers the risk of PTL, by 60% [A}
{BV may reflect chronic intrauterine infection}
Vaginal clindamycin cream in BV-positive women :
an increase in PTL
{topical therapy adequately treats vaginosis, but fails
to affect pre-existing intrauterine infection}

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30. b. Asymptomatic bacteriuria
{increased risk of pyelonephritis in women
presenting with asymptomatic bacteriuria.}
Screening
Antibiotic treatment [A].

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31. c. Group B streptococcal colonization (GBS)
{Preterm infants are more susceptible to early-onset
GBS infection, acquired during passage through the
birth canal}.
evidence that it is one of the major causal organisms
behind spontaneous prematurity: weak}
Screening
High risk group
combined low vaginal/rectal swab
Intrapartum prophylaxis
{1. antenatal antibiotics have not been shown to lower perinatal
transmission.
2. prophylactic treatment of GBS: increase in neonatal infections with
penicillin-resistant Escherichia coli.
3. antibiotics have the potential for harm}.

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32. d. Other organisms
Chlamydia trachomatis,
Neisseria gonococcus and
Trichomonas vaginalis have been associated with
preterm delivery: a causal link has not been
established.
Treatment of chlamydia:
No decrease PTL
prevent perinatal transmission.
Treatment of chlamydia and gonococcus
include contact tracing and treatment of the partner.
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33. 2. Cervical cerclage
Indication
1. 3 or more previous PTL and/or 2
nd
T losses.
2. History of one or more spontaneous mid-trimester
losses or preterm births +TVS: cervix is 25 mm or
less

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34. 3. Progesterone supplementation
Indications: (ACOG 2008)
1. Singleton (not multiple) pregnancy and a history of
PTL < 37 w
2. Asymptomatic women with an incidentally
identified very short cervical length (< 15 mm)
Effect
reduce the incidence of PTL by 50%


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35. Forms and Dose
I. Vaginally:
•Gel (Crinone 8%, 90 mg/day),
•Capsules (Uterogestan 200 mg twice daily)
•Suppositories (cyclogest 200 mg daily,
prontogest 200 mg daily)
from 22 - 34 w
II. IM:
•17-alpha-hydroxyprogesterone caproate weekly of
250-1000 mg, from 16-37 w
•Prontogest100 mg= Gestone

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36. 4. Lifestyle modification
1.Stop smoking [C].

Hospitalization for bed rest: an increase in PTL
[A].
Sexual abstinence and/or psychological support:
should not be recommended as a universal or
general measure in high-risk women.


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37. MANAGEMENT OF
SYMPTOMATIC WOMEN
Assessment:
A. Maternal
B. Foetal
Therapy
1. Corticosteroids
2.Tocolytics
3.Antibiotics
4.Emergency cerclage
5.In Utero transfer
6.Mode of delivery
7.Anathesia


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38. I.Assessment
A. Maternal
Objective: chance of delivery within the next 7 d.
1. Low risk: Observation and review.
2. High risk: Treatment

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39. History
Risk factors
Current symptoms
•low backache or cramping: often cyclical.
•Vague complaints: pelvic pressure or increased
discharge: common.
•Vaginal bleeding: should be taken seriously.
UC+ closed cx + bleeding
UC+ 2 cm cx dil
Risk of delivery within 7 days

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40. Examination

Abdominal examination
uterine tenderness, suggesting abruption or chorioamnionitis.
Speculum examination
Pooling of amniotic fluid, blood and/or abnormal
discharge .
Visual assessment of cervical dilatation:
accurate as digital examination findings.
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41. limit digital examinations
speculum assessment is inconclusive
{1. stimulate prostaglandin
2. introduce organisms into the cervical canal
3. Reduce latent interval before labour}.
Repeat vaginal examination
in 1-4 h (guided by the severity of the symptoms)
in the absence of secondary tests.


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42. Investigation
1. Cervical length measurement
In symptomatic women:
Accepted safe length is 3 cm
Cx length > 3cm: No risk of PTL
Cx length <2cm: 70% will deliver PT


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43. 2. Bedside fibronectin testing
:rapid assessment of risk in symptomatic women who do not have advanced
dilatation.
Igreater predictive value than digital examination.
30% of women with a positive fibronectin test delivered within 7 days, compared
with only 10% of women who were 2-3 cm dilated.
positive fibronectin test carries a risk of delivery within 28 days of up to 70%,
regardless of initial cervical length. Combination testing refines the prediction of
deliveries in the next 7 days.
positive fibronectin test but a normal cervical length, only 5% will deliver within 1
w.
However, if the cervix is also short when tested, the risk of delivery within 7
days climbs to 50%
This is particularly useful, as many interventions (tocolytics, steroids and in-
utero transfer) should be based on this end-point.




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44. B. FETAL
1.CTG:
During pregnancy:
Maternal steroid therapy can suppress both fetal activity and heart
rate variability.
Interpretation: difficult
 Applying criteria used at term is inappropriate.
Baseline rate is more important than either decelerations or
variability.
During labour:
Moderately PTL: no benefit from continuous as opposed to
intermittent monitoring [B]
 Severe PTL: Decisions regarding monitoring must be discussed with
parents.
Intervention on the basis of FHR monitoring may not be justifiable
near the limits of viability.


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45. 2. Umbilical artery Doppler
AED or RED: a short-term return of end diastolic flow is
commonly observed.
When labour has started or is thought to be imminent

3. US
a. Presentation
{clinical palpation is unreliable}
b. Fetal weight
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46. II. THERAPY
1. Corticosteroids: RCOG,2011
When:
 between 24 and 35 W
 between 24 and 36 W (SFGA)
 between 24 and 39 W (elective CS)
Dose:
Betamethasone: 12 mg given IM in two doses or
Dexamethasone: 6 mg given IM in four doses
Betamethasone Vs Dexamethasone:
No difference
improved neurological outcomes with betamethasone.

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47. Effect:
Significant reduction:
RDS
neonatal death
intraventricular hge.
Most effective:
24 h after last dose and up to 7 days

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48. Single course
Harmful effects of repeated doses:
increased sepsis in PPROM
restricted fetal body and brain growth
adrenal suppression.
increased risk of neonatal death seen when 3 or
more courses of antenatal steroids
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49. 2. Tocolytics: RCOG, 2011
Effect:
prolongation of pregnancy for up to 7 days
No significant effect on preterm birth
No clear effect on perinatal or neonatal morbidity.
Indication
1.Completing a course of corticosteroids
2.In utero transfer.
Maintenance therapy is not recommended.

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50. Nifedipine Vs atosiban (Tractocil)
comparable effectiveness in delaying birth for up
to 7 days.
Price is 1/10
Nifedipin Vs Beta-agonists or indomethacin
improvement in neonatal outcome
fewer maternal adverse effects
less risk of rare serious adverse events.
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51. Dose
Nifedipine:
Initial oral dose: 20 mg followed by 10–20 mg three
to four times daily, adjusted according to uterine
activity for up to 48 hours.
A total dose above 60 mg appears to be
associated with a three- to four-fold increase in
adverse events.
Atosiban
Initial bolus dose of 6.75 mg over 1 minute, followed by an infusion of
18 mg/h for 3 h, then 6 mg/h for up to 45 h (to a maximum of 330 mg).
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52. Indomethacin:
orally or rectally.
50 to 100 mg is followed at 8-hour intervals not to
exceed a total 24-hour dose of 200 mg. or
50 mg Loading dose, then 25-50mg /6hs
Serum concentrations usually peak 1 to 2 hours
after oral administration, whereas levels after rectal
administration peak slightly sooner.
limited use to less than 72 h and only below 30 w
{oligohydramnios, it is reversible}


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53. 3. Antibiotics
Uncomplicated PTL
no evidence of benefit
significant increase in the incidence of cerebral
palsy.

Preterm PROM
significant advantages
No increase in cerebral palsy in the long term
Erthryomycin
(250 mg qds for 10 d)


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54. Thyrotropin-releasing hormone, vitamin. K or phenobarbitone
RCT: not beneficial [B].

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55. 4. Emergency cervical cerclage
Indication:
mid-trimester
minor symptoms (pelvic pressure, watery discharge
membranes bulging into the tipper vagina.
Contraindication:
1.symptomatic contractions
2.intrauterine infection: 10%of chorioamnionitis are
clinically obvious
Reassess the cervical dilatation after several hours. This can be precisely
and repeatedly measured using transperineal US.


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56. 5. In-utero transfer
To a unit with adequate neonatal facilities, where
these are not available in the admitting unit
improve outcome for babies.
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57. 6. MODE OF DELIVERY
 <26 W:
Vaginal delivery
{fetal morbidity and mortality, the difficulty in diagnosing intrapartum
hypoxia/acidosis and the maternal risk} do not justify
CS has not been shown to improve neonatal
outcomes}.
 {As gestation advances, both neonatal outcomes and the ability to
diagnose fetal compromise improve, and intervention for fetal reasons
becomes universally appropriate}.
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58. Breech
CS
{an increased mortality and morbidity to the preterm breech born
vaginally. recent similar studies that conclude the opposite}.
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59. Type of CS
Membranes ruptured:
De Lee vertical lower segment
{At the earliest gestations, the lower segment is
poorly formed
does not appear to carry any greater risk than a
conventional transverse incision} [D].
Membranes intact:
Transverse incision

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60. 7. ANALGESIA
 Epidural
Benefits
1. Avoiding expulsive efforts before full dilatation or
a precipitous delivery, a relaxed pelvic floor and
perineum
2. Ability to proceed quickly to CS.
Narcotics
prolonged effects on a preterm infant with limited
metabolic capacity.

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61. SUMMARY
Beneficial antenatal treatments for high-risk
women include
metronidazole for bacterial vaginosis
antibiotics for asymptomatic bacteriuria
cerclage for three or more 2
nd
T losses or PTL
progesterone supplementation.

Hospitalization for bed rest leads to an increase
in preterm births.


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62. Tocolytics have no significant benefit on perinatal
mortality or the prolongation of pregnancy to term,
but do reduce the number of women delivering
within 48 hours by 40%.

There is no evidence of benefit and some
evidence of harm associated with the use of
antibiotics in uncomplicated preterm labour with
intact membranes.

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63. In symptomatic women, the following factors are
associated with a high risk of delivery within 7
days:
cervical dilatation >3 cm,
ruptured membranes or
any vaginal bleeding.

 A single course of maternal steroids given
between 24 and 35 w and received within 7 days of
delivery results in markedly improved neonatal
outcomes.
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64. After the diagnosis of preterm labour
neonatology consultation,
fetal monitoring,
mode of delivery
intrapartum antibiotics if a known GBS carrier.


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65. Thank you

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