Preterm labour( PTL) &premature rupture of membranes

Definition Definition :Labour which occurs from the viability of the fetus ( completed 24 weeks GA) until the completion of 37 weeks of gestation

Incidence: 5.7% white European 10% in Africans

Predisposing factors for preterm labourEpidemiologicalBMI< 19Low social class, blackunmarried/unsupported / smokerYoung age& old age anemia or polycythemiaPrevious preterm labour( the single most effective predictor), 20% for one PTL, 40% for 2 PTLElective delivery ( iatrogenic 30%)PET maternalIUGR-- fetal

PTL( continued risk factors)MedicalROM- 1/3Multiple pregnancyPolyhydramniosMedical disordersSystemic infection, chorioamnionitisCongenital or acquired abnormalities of the uterus(Cervical incompetence, bicornuate uterus, fibroids)Vaginal infection ( e.g. bacterial vaginosis)APHIntra-abdominal surgery

Diagnosis History: ROM Backache, cramping abdominal pain Pelvic pressure, increased vaginal discharge

Examination: Abdominal exam: uterine tenderness-abruptio, chorioamnionitis.Speculum : pooling of amniotic fluid, blood & /or abnormal discharge. cx dilatation( visual assessment), digital exam should be limited ( stimulate PG production& may introduce organisms into cx canal).

Differential diagnosisUTIPlacental abruptionGastroenteritisConstipationRed degeneration of fibroid

Investigations Fetal fibronectin: glue like protein binding the choriodecidual membranes. Any disruption of the choriodecidual interface results in release of FFN & detection in cervico- vaginal section . This disruption precedes preterm laborCx length: measurement by transvaginal ultrasound( normal cx length~ 3.5 cm) cx shortening, dilatation, & funneling of the membranes down the cx canalRepeat vaginal exam( in 1-4 hours) in the absence of specialized tests

ManagementBed restHydrationMaternal steroidsTocolyticsAntibiotics Fetal assessment

PTL( management)Bed rest & hydration: Increase uterine blood flow & quieting the uterus. Dehydration increased levels of ADH. ADH may cross react with oxytocin receptors &lead to contraction, so hydration decrease ADH & contractions. Lying on her side & IV fluid

Maternal steroids:Steroids decrease RDS in preterm infants . Stimulate type II pneumocytes to produce surfactant which reduces alveolar surface tension. All women between 24 & 34 weeks of pregnancy at risk preterm labour are candidates for antenatal corticosteroid delivery.

TocolysisBeta mimeticsMagnesium sulfateCalcium channel inhibitorsProstaglandin inhibitorsOxytocin antagonist

Beta mimetics: Two beta mimetics commonly used for preterm labor- ritodrine (Yutopar)& terbutaline.

Side effects : tachycardia, headaches, hyperglycemia, hypokalemia.The most serious is pulmonary edema & in rare cases maternal deathContraindicated : symptomatic cardiac disease, uncontrolled diabetes ,hyperthyroidism.

Magnesium sulfate: Side effects: flushing, headache, fatigue, diplopia.At Toxic level of Mg ( > 10mg/dl)- respiratory depression, hypoxia, &cardiac arrest.

Deep tendon reflexes depressed& lost at< 10 mg/dl so rule out Mg toxicity with serial reflex checksPulmonary edema may occur

Ca- channel blockers: nifedipineSide effects: headache, flushing, and dizzinessGiven orally

Prostaglandin inhibitors:Indomethacin-NSAIDS.Side effects:Mother: minor , fetal premature constriction of ductus arteriosus, pulmonary hypertension & oligohydramnios secondary to renal failureIncreased risk of necrotizing enterocolitis & intraventricular haemorrhage.Oxytocin antagonists: atosiban

Antibiotics

Routine use of antibiotics in uncomplicated preterm labour did not confer benefits

10 day course of erythromycin lead to improved neonatal outcome after PROMSome give antibiotics during labour if GBS status is unknown

Fetal assessmentUltrasound: fetal presentation, estimated fetal weight, AFI.NST

Mode of deliveryThe case should be evaluated

Premature rupture of membranes ( PROM)& preterm ROM

Preterm ROM: ROM occurring before 37 wk.Premature ROM(PROM):ROM before the onset of labour.If two occur together PPROMProlonged PROM: ROM > 24 hrs before delivery(or 18 hrs)

Preterm ROMCommon cause of preterm labour & chorioamnionitis50% go into labour within 24 hrs75%within 48 hrsThese % correlate inversely with GA at ROMProlonged PPROM associated with increased risk of chorioamnionitis, abruption,& cord prolapse

Clinical featuresHistory: gush of fluid per vagina followed by continuous dribbling.Fetal movement may reduced in strength or frequencyExamination: PR, temp, appearanceAbdominal exam: may oligohydramnios, uterine tenderness if chorioamnionitisSpeculum exam(definitive DX):pool of amniotic fluid post vagina is dx, positive cough signVisualize the cx for dilatationDigital exam should be avoided

Differential diagnosisUrine loss: Incontinence & UTI are common in pregnancyVaginal infectionLeukorrhoea: the cx glands often become hyperactive during pregnancy

Investigations Nitrazine test amniotic fluid is alkaline but vaginal secretions are acidic. Alkaline PH black stick. False positive blood ,semen &urineGenital tract swabs HVS & for GBSMaternal wellbeing vital signs, WBC, CRP early markers of infectionFetal wellbeing serial NST, fetal tachycardia is suggestive of chorioamnionitis

5.Ultrasound AFI- oligohydramnios support PROM6.AmniocentesisC&S, gram stain

Management

Preterm ROM : depends on GABalance risk of prematurity & risk of infection

Between 32-34 weeks

The use of antibiotics leads to longer latency period prior to onset of labour, so ampicillin with or without erythromycin is recommended in PPROM

Tocolysis contraindicated

Steroids are recommended

Any patient who shows signs of infection or fetal distress needs to be delivered

Maternal & fetal complications associated with PROMChorioamnionitis Hyaline membrane disease( HMD)Pulmonary hypoplasia-frequent when PROM occurs before 26 wk& latent period > 5 wkAbruptio placentaFetal distress- the most common is variable deceleration reflecting umbilical cord compression caused by oligohydramniosFetal deformities; facial & skeletal deformities in prolonged PROM