Management of preterm prelabour rupture of the membranes
PPROM occurs in 2% of all deliveries and accounts for approximately one-t hird of PTBs. Following PPROM, 50% will deliver within the next 7 days, 75% within 2 weeks, and 85% within the month.
As with PTB, the earlier the gestational age at which PPROM occurs, the more negatively this will affect postnatal survival. The presence of amniotic fluid is essential for fetal lung development. Locatelli et al. found that pregnancies with a median residual amniotic fluid pocket persistently less than 2 cm were at highest risk of poor perinatal and long-term neurological outcome while pregnancies with a pocket greater than 2 cm had significantly better perinatal outcome (73-92% survival) and lower pulmonary hypoplasia rates (89, 90).PPROM prior to viability
Further management following confirmation of PPROM will be dependent on the gestation at which PPROM occurred. Parents require detailed counselling regarding the poor outcomes. Prior to viability (until the pregnancy reaches viability, if they are asymptomatic of pain or bleeding. Broad-spectrum antibiotics are likely to be of no benefit if the latency period has been a long one and there remain no signs of maternal infection. Corticosteroids should be considered only once viability is reached. AMIPROM, a pilot RCT of amnioinfusion versus expectant management for early PPROM, was the first study to examine outcomes in pregnancies (n = 56) where PPROM occurred between 16 and 24 weeks of pregnancy. The proportion of healthy survivors (without respiratory or neurological disability) was disappointingly only 7% overall. The perinatal mortality rate was extremely high at 67.9%. At present, there is insufficient evidence to recommend amnioinfusion in the management of PPROM and further definitive studies are required (91).
PPROM between 23 and 34 weeks
If PPROM occurs between 23 and 34 weeks’ gestation, conservative management is generally adopted if there is no sign of overt chorioamnionitis.
Corticosteroids are given in view of the high rate of delivery within 7 days. A vaginal swab for group B Streptococcus culture should be taken. Broad-spectrum antibiotics have been evaluated in 22 randomized trials of over 6000 women, classes, doses, and regimens of use show substantial variations but overall, antibiotics improved latency at 48 hours and 7 days, with less chorioamnionitis and a reduction in neonatal morbidity. However there is variation within antibiotics and the largest trial found that ampicillin-clavulanic acid increased rates of necrotizing enterocolitis, and erythromycin alone prolonged pregnancy and reduced the incidence of death and/or major cerebral abnormality and chronic neonatal lung disease (92). Seven-year follow-up of these infants showed no benefit or risk from antibiotic treatment. Therefore, 10 days of erythromycin is given at a dose of 250 mg orally four times a day when PPROM occurs.PPROM at greater than 34 weeks
If PPROM occurs at or after 34 weeks' gestation, traditionally induction of labour has been recommended due to the low rate of neonatal morbidity and fears that conservative management may increase the risk of infection or uterine cord compression. The largest randomized trial assigning 1839 women to expectant management (n = 915) of PPROM versus immediate delivery (n = 924) for women with PPROM without signs of infection between 34 and 36+6 weeks showed the incidence of neonatal sepsis was not significantly different between the two groups (2% of neonates assigned to immediate delivery vs 3% assigned to expectant management), which has also been reflected in smaller trials (89, 90). Neonates born to mothers in the immediate delivery group had increased rates of respiratory distress syndrome (8% vs 5%), the use of mechanical ventilation (12% vs 9%), and spent more time on special care (median 4.0 days vs median 2.0 days). On the other hand, the expectant management group had higher rates of antepartum/intrapartum haemorrhage, intrapartum fever, postnatal antibiotic use, and longer maternal hospital stay, but a lower risk of caesarean delivery. Therefore, it is reasonable to offer conservative management provided there are no clinical signs of infection and the woman can be adequately monitored as an outpatient.