Introduction
The onset of spontaneous labour between 28 and 37weeks of pregnancy.It occurs in between 7-12% of pregnancies but more frequently between 28-34weeks.
The condition is significant because of its contribution to high perinatal morbidity and mortality being second only to congenital foetal abnormalities,the maternal morbidity and the increased costs of taking care of the preterm neonates in intensive neonatal units.
Diagnosis:
Presence of two or more of:
1. Regular uterine contractions of more than 2 in 10minutes by palpation or tocometer
2. Effacement and dilatation of cervix-atleast 2cm dilatation and reasonable degree of effacement
3. Passage of bloody mucus vaginal discharge
Assessment:
I. Accurate assessment of gestational age[LMP,previous scan date]
II. Foetal weight&heart rate estimation by ultrasound if feasible
III. Foetal presentation[to exclude abnormal lie&position]
IV. General maternal condition:-palor,Bp,heart,chest etc
V. Laboratory :
-FBC,differential;MP
-Urine-mcs,urinalysis
-Scan-foetal lie,position,presentation,placenta location,cervical length
-Speculum vaginal examination-bacterial culture&to exclude cord prolapse if foetal membranes have ruptured,and by sighting determine effacement and cervical os dilatation;also to obtain cervical mucus swab for fibronectin assay.
Avoid digital vaginal examination unless immediate delivery is inevitable.
Haematologic work-up for haemorrhaging cases.
Treatment of symptomatic preterm labour in singleton pregnancy:
i. Admit for bed rest
ii. Site IV line
iii. Treat for malaria
Further treatment depends on:
a. Estimated gestational age
b. Foetal weight
c. +/- other complications e.g. PPROM
Two options available:
A. Expectant(observation)
B. Intervention-immediate delivery
A. Expectant treatment
Usually for gestational ages 28-34wks and uncomplicated preterm labours.
Consideration is given to:
i. Bed rest,hydration
ii. corticosteroids mandatory
-betamethasone 12mg IM every 24hours X 2doses[drug of choice]
-dexamethasone 6mg 12hrly X 4doses
Multiple administration of steroids after the initial 48hrs is unnecessary and may even be harmful
iii. Tocolytics:suppress uterine contractions if bed rest and infusions fail to do so;aim is to suppress uterine contractions for 48hrs to allow steroid administration only.
Choice of tocolytic depends on availability,affordability,adverse effects.
Objective of tocolysis-to gain some time to enable corticosteroids improve neonatal outcome.
Maintenance tocolysis has doubtful effect,so not recommended.
RCOG recommends:
Atosibane or nifedipine as 1st line drug(tocolytic)
Atosibane is an oxytocin antagonist,not easily available but expensive
Other tocolytic groups are:
i. Progesterone(17α-hydroxyprogesterone caproate)
ii. Betamimetics e.g. Ritodrine,Salbutamol,Terbutaline
iii. Magnesium sulphate
iv. Prostaglandin synthetase inhibitors e.g. indomethacine
Contraindications to tocolysis in Preterm labour.
a) Foetal:
-death,distress,chorioamniotitis
-estimated foetal weight≥2500gm
-Erythroblastosis foetalis
-severe IUGR
b) Maternal:
-severe hypertension
-pulmonary or cardiac disease
-advanced cervical dilatation beyond 4cm
-maternal haemorrhage e.g. abruption,placenta praevia,DIC
iv. Antibiotics[prophylactic/therapeutic]
B.Interventions[conduct of preterm labour/vaginal delivery]
Guidelines
1. desirable that intensive care neonatal unit be present and made functional,otherwise in-utero transfer is recommended.
2. Presence of skilled midwives,senior resident and consultant obstetric/paediatric staff
3. Reduction of doses of sedatives/narcotic analgesia or None at all
4. Epidural analgesia useful
5. Generous episiotomy is necessary
6. Delay clamping of cord for about 60seconds with baby held below placental bed
7. Avoid precipitate delivery of the head
8. Obstetrics outlet forceps may be used with no force applied
9. Vacuum extraction is contraindicated
10. Paediatrician to resuscitate preterm neonate and manage at intensive care unit
Indications for C/S in preterm labour
1. Preterm breech with estimated foetal weight 1.5-2.0kg
2. Severe pre-eclampsia/eclampsia
3. Major degree placenta praevia
4. Foetal distress
At C/S,a low vertical incision may be choice if lower uterine segment is not formed.
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