Preterm labour

Question 1

What is the definition of preterm labour?

Answer 1

labour after fetal viability (22 weeks) & before fetal maturity (37 weeks)

• early preterm labour: 22 weeks - <34 weeks
• late preterm labour: 34 weeks - < 37 weeks

Question 2

What are the causes of preterm labour?

Answer 2

• spontaneous
• idiopathic
• iatrogenic
• multiple pregnancy
• polyhydramnios, APH, PE
• preterm premature rupture of membranes
• genital tract infection (bacteria vaginosis)
• cervical incompetence
• uterine anomalies

Question 3

What is the clinical picture of preterm labour?

Answer 3

From history
- previous PTL, PPROM
- recurrent mid-trimesteric pregnancy loss
- short cervical length
- predisposing factors

Symptoms
- pain: true labour pain, pelvic pressure, low back pain
- vaginal bleeding
- vaginal discharge

Signs
- sterile speculum exam -> cervical dilatation observed, membrane bulging, fluid pooling out of cervix

Question 4

What investigations are done in case of preterm labour?

Answer 4

1- ambulatory uterine monitoring
2- fetal fibronectin >50mg/ml (should not be detected in the vagina after 22 weeks)
3- cervical length measurement: <20mm 1st trimester & <15mm in 2nd trimester
4- OB ultrasound -> for fetal anomaly, maturity, twins, AFI, placental pathology
5- assessment of fetal well-being

Question 5

What are the complications of preterm labour on the fetus?

Answer 5

• RDS
• broncho-pulmonary dysplasia
• necrotizing enterocolitis
• hospital acquired infections
• intra-ventricular hemorrhage
• retinopathy of prematurity
• patent ductus arteriosus

in the long tern -> cerebral palsy & poor school performance

Question 6

How is preterm labour prevented?

Answer 6

• avoid elective delivery < 39 weeks
• prophylactic progesterone -> 16 - 34 weeks
• cervical cerclage -> if +ive history of recurrent mid-trimesteric loss with cervical insufficiency (14-16 weeks)
• prophylactic corticosteroids -> 24 - 34 weeks
• MgSO4 -> 24 - 34 weeks
• if PPROM -> erythromycin or clarithromycin
• if chorioamnionitis + SIRS -> ampicillin + gentamicin + metronidazole -> TOPS
• tocolysis for 24 - 48 hours only -> nifdipine, atosiban, prostaglandin inhibitors