Obstetrics Dr.eman
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Preterm Labour
Preterm labour : delivery of a baby before 37 completed weeks of pregnancy.
2 clinical subtypes :
Indicated PTL, undertaken due to maternal or fetal reasons, make up 1\3 of PTL.
spontaneous PTL responsible for the remaining 2\3 .
• Mildly PTL: 32—36+6 wk
• Moderately PTL: 28—31+6 wk
• Extremely PTL: 24—27+6 wk
Aetiology of PTL
1.Infection: Uterine cavity is sterile but vagina contain commensal bacteria,
these bacteria may ascend through cervix & reach fetal membrane, this will
increase PG release Causing uterine contraction or membrane rupture.
Early onset neonatal sepsis , maternal postpartum endometritis & histological
chorioamnionitis are all more common after PTL.
2. Overdistention : multiple pregnancy & polyhydramnios .
3. Vascular : disturbance at uteroplacental interface may lead to intrauterine
bleeding, blood irritate uterus leading to contraction.
4. Surgical procedure & intercurrent illness: pyelonephritis or pneumonia can
lead to PTL either due to blood borne infection to uterine cavity or indirectly to
chemical triggers such as endotoxin.
5. Abnormal uterine cavity : congenital malformation , fibroid in low position.
6. Cervical weakness: due to previous surgical damage or congenital defect.
7. idiopathic: especially mildly PTL between 34-36 wk
Obstetrics Dr.eman
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Risk factors
Major risk factors(non-modifiable):
Previous PTL: after one PTL, risk in next pregnancy 20%, after two PTL, risk will be
40%
-- multiple pregnancy
-- uterine abnormality
-- cervical damage ( cone Bx, D&C)
-- factor in current pregnancy: recurrent APH, intercurrent illness , surgery
Minor risk factors(non-modifiable):
--teenage multipara
--parity 0 or more than 5
--ethnicity (black)
--poor socio-economic status
--low level of education
Modifiable:
smoking, low BMI, interpregnancy interval less than 1 yr & drug abuse.
Management of asymptomatic high risk
1.Outside pregnancy:
Smoking cessation
Increase interpregnancy interval
Dietician referral for women with low BMI
2. During pregnancy:
-- early dating scan
--screening for bacterial vaginosis: oral metronidazole can decrease risk of PTL
significantly.
--screening for asymptomatic bacteriuria & treating with antibiotic.
-- screening for GBS infection: which acquired during passage through birth
canal, so that only intrapartum prophylaxis should be given
--screening for gonorrhea, chlamydia & trichomonas which have been
associated with PTL.
--cervical ultrasound: cervical length can be assessed by TAS or TVS, TVS is
preferable because TAS is required full bladder which cause false lengthening of
cervix, cervical length less than 26mm is considered short, cerclage should be
considered.
--cervicovaginal fibronectin testing: fFN is a glue like protein binding
choriodecidual membrane , it rarely present in vaginal secretion between 24-
34wk. Any disruption in choriodecidual membrane lead to detection of fFN in
cervicovaginal secretion
Obstetrics Dr.eman
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Management of symptomatic women
• History:
low backache
Cyclical cramping
Pelvic pressure
Increased vaginal discharge
Vaginal bleeding
• Examination
Vital signs
Abdominal examination: uterine tenderness suggest abruption or
chorioamnionitis
Speculum examination: provide visual assessment of cervical dilatation,
abnormal discharge or bleeding(digital examination stimulate PG production &
introduce organism to cervical canal).
• Investigation:
CBC, RBS,MSU & urine for C&S
Culture for GBS & HVS for BV
Ultrasound assessement for cervical length, fetal weight, presentation, &may
detect any underlying cause such as twin.
Adequate hydration , cease uterine contraction in 20% of cases
Allow PTL to proceed if
• Cervix is 4 cm or more dilated
• Membranes are rupture
• Maternal medical diseases e,g PIH or sever PE
• Chorioamnionitis
• Bleeding suggestive of placental abruption
• Fetal demise or congenital anomaly incompatible with life
• Fetal distress
• IUGR
• Adequate fetal lung maturity
Obstetrics Dr.eman
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Inhibit PTL if:
• Membrane are intact
• Gestational age less 34 wk
• No evidence of fetal or maternal infection
• Cervix is less than 4 cm dilated
Therapy
•
Transplacental therapy
1. steriod:
Single course (2 doses of 12mg dexamethasone 12 hr apart i.m. or 12 mg
betamethasone 24 hr apart i.m).
Given between 28-34wk , before 28 there is no benefit & after 34 there is
adequate surfactant production
Maximal benefit is after 48 hr & last for 7 days, courses received less than 48 hr
or more than 7 days still result in reduction in RDS.
Single course but not repeated courses , because repeated course increase
sepsis in PPROM, affect brain growth of fetus, & adrenal suppression.
Corticosteriod cause significant disruption in glycemic control in diabetic
women, this effect last for 24 hr after 2nd dose of steriod.
2. tocolytic:
Beta agonist:- such as ritodrine or sulbutamol, have significant maternal side
effect: Hypotension, Tachycardia, Anxiety, Acute cardiopulmonary compromise
when given with large volumes of fluid, in multiple pregnancy & in women with
cardiac disease
Magnesium sulfate
Intial dose: 6 g over 15-20 min iv
Titrating dose: 2 g\hr until contraction cease
Maintenance dose : maintain dose for 12 hr, then 1 g\hr for 24-48 hr.
When you start mg you should monitor serum level & start a chart including
Vital signs (RR is the most important)
UOP( bc it excreted through kidneys)
Patellar reflex
Obstetrics Dr.eman
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Nifidipine(ca channel blocker):
Loading dose : 30 mg(3 cap) , if contraction persist after 90 min , give additional
20 mg , if contraction is suppressed , 20 mg is given orally every 6 hr for 24 hr
then every 8 hr for another 24 hr
If contraction persist 60 min after the 2
nd
dose , treatment should be considered
a failure. SE – Hypotension , headache, flushing, & tachycardia.
Prostaglandin synthetase inhibitors:
Indomethacin (orally or rectally) should be used for short term (less than
3days), less than 32 wk of gestation.
SE– impair fetal renal function , increase risk of neonatal necrotizing
enterocolitis, intracranial hge, prematue closure of ductus arteriosus,
indomethacin also cause reversible oligohydramnios.
Oxytocin receptor antagonist (atosiban)
Progestational agent: in women with a documented history of a previous
spontaneous birth at less than 37 weeks.
3. Antibiotic
: no benefit of antibiotic in uncomplicated preterm labour.
In utero transfer: indicated when neonatal care facilities are not available in the
admitting unit.
Preterm prelabour rupture of membrane (PPROM)
Rupture of fetal membrane prior to onset of labour before 37 wk.
PPROM prior to 23 wk is associated with neonatal hypoplasia & neonatal death.
• Management:
History: watery vaginal discharge as a gush or stream.
Examination:- vital signs for fever
-abdominal for uterine contraction, FHR, & uterine tenderness.
-speculum: pooling of liqour in vagina
• clinical surveillance for chorionamnionitis including regular recording of
maternal temperature and heart rate and cardiotocography. A rising white
cell count or a rising C-reactive protein (CRP) level may indicate the
development of chorionamnionitis.
• Lower genital tract swab
Obstetrics Dr.eman
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Chorioamnionitis
Maternal pyrexia (Temp ≥ 38) + 2 of following:
Maternal tachycardia
Fetal tackycardia
Uterine tenderness
Foul smelling vaginal discharge
Elevated C-RP or WBC
Recommended Management of Preterm Ruptured Membranes
Gestational Age 34 weeks or more
• Proceed to delivery, usually by induction of labor
• Group B streptococcal prophylaxis is recommended
32 weeks to 33 completed weeks
• Expectant management
• Group B streptococcal prophylaxis is recommended
• Corticosteroids—no consensus, but some experts recommend
• Antimicrobials to prolong latency
24 weeks to 31 completed weeks
• Expectant management
• Group B streptococcal prophylaxis is recommended
• Single-course corticosteroids use is recommended
• Tocolytics—no consensus
• Antimicrobials to prolong latency (erythromycin)
Before 24 weeks
• Patient counseling
• Expectant management or induction of labor
• Group B streptococcal prophylaxis is not recommended
• Corticosteroids are not recommended
• Antimicrobials—there are incomplete data on use in prolonging latency