Pre-Term Labour

Definition

Onset of uterine contraction with frequency and intensity sufficient to cause progressive cervical dilatation and effacement prior to term gestation (22 – 37 weeks)



Risk for pre-term labour

1)    Socioeconomic factors

Low socioeconomic status
Young maternal age < 16 years
BMI < 19
Unsupported, Unmarried
Maternal smoking

2)    PPROM
3)    Previous pre-term delivery
4)    Intrauterine death
5)    Multiple gestation
6)    Genital tract infection
7)    Polyhydramnios
8)    Cervical incompetency
9)    Asymptommatic bacteriuria
10)    Systemic febrile illness
11)     Fetal anomalies
12)    Uterine abnormalities
13)    Iatrogenic (for severe pre-eclampsia, chorioamnionitis, symptommatic placenta praevia and abruptio placentae)

Symptoms

Increased uterine activity (contractions and tightening)
Passage of show
Lower abdominal pain and cramping
Vaginal pressure
Vaginal discharge
Per vaginal bleeding

Signs

Buldging of membranes
Engagement of presenting parts
Cervical effacement
Cervical dilatation
Palpable uterine activity
Ruptured membranes

Routine physical examination

1)    Maternal vital signs and urine dipstick
2)    Abdominal examination (presentation, lie)
3)    Sperculum examination (status of cervix, membranes, swab taking)

Investigations

1)    Urine microscopy and culture
2)    High vaginal swab – Chlamydia and Gonorrhoea
3)    CTG
4)    Ultrasound (dating, presentation, liquor, anomalies, estimated fetal weight)
5)    Cervico-vaginal swab for Fetal fibronectin
6)    TVS for cervical length and funneling of internal os

A note on fetal fibronectin

Extracellular matrix glycoprotein produced by fetal membranes and deciduas
Main function is to maintain adhesion in between deciduas and membranes
Presence of disruption of chorio-decidual interface, leading to leakage of fibronectin
Collected by cervico-vaginal swab
A level of > 50ng/ml -> associated with pre-term delivery

Good clinical aid, since negative predictive value is near 100%
To some consultants, is a re-assuring sign

Management of preterm labour

1)    Liason with neonatologist.
2)    In local facilities is inadequate, in-utero transfer is better than ex-utero transfer.

Corticosteroids

Every mother with imminent risk of pre-term labour should be given corticosteroids
To reduce incidence of respiratory distress syndrome in infants

12 mg Dexamethasone 12 hours apart IM injection given weekly upto 34 weeks

< 32 weeks – must give
32-34 weeks – discuss with MO/specialist
> 34 weeks – no need (unless indicated)
To achieve maximum benefits, delivery ideally must occur 24-48 hours after adminstration

Contraindications : TB, chorioamnionitis, porphyria
Benefits in Diabetic mothers : uncertain

Tocolytics

Eg, MgSO4, ritodrine, atorsiban, salbutamol, indomethacin, etc
In Melaka GH, Ventolin infusion is given

Why given?

To delay delivery for 24-48 hours, thus maximizing the benefits of corticosteroids
For safer in-utero transfer

Investigations to be done before infusion :

FBC
BUSE (correct hypokalemia if any)
Random blood sugar 4 hourly
ECG (cardiac abnormalities)
Auscultation of lungs

Contraindications :

Cardiac disease
Hyperthyroidism
IUD
Fetal distress
Fetal anomalies
Antepartum haemorrhage
Chorioamnionitis
Cervical dilatation > 4cm

Diabetes, PIH/PE (relative)

Ventolin infusion only to be given by MO/specialist
Procedure :

1)    1 ampule (5 mg in 5ml) of ventolin is diluted with 500 ml of normal saline. Hence it contains 10mcg/ml of ventolin
2)    A rate of 10-45 mcg/ml of ventolin is required to cease uterine contraction
3)    Start IV infusion with 10mcg/min, then increase every 10-15 minutes
4)    Look for any dimunition of strength, frequency and duration of contraction
5)    Maternal pulse is monitored while on drip, and infusion rates should be adjusted according to changes of pulse
6)    Once contraction ceases, maintain the same infusion rate for 1 hour, then reduce it by 50% at 6 hourly interval
7)    4-6 hours after contraction ceases, 4mg of ritodrine tablets can be given 3-4 times/day
8)    Maintain drip until 24 hours of last dose of dexamethasone has passed

While the patient is on drip, look for :

Maternal pulse > 120 bpm
Fetal heart rate > 180 bpm
Nausea, vomiting, breathlessness -> STOP drip and inform MO/specialist

Also check :

4-6 hourly lung auscultation
BUSE for hypokalemia and hypocalcemia

Features of ventolin toxicity :

DBP < 60 mmHg
Chest pain
Nausea, vomiting
Tachycardia, Palpitation
Basal crepitations

Category: Obstetrics Notes