The key management of preterm premature rupture of membranes (PPROM) includes prevention of infection, promotion of fetal lung maturation and anti-preterm delivery, prolongation of gestational age, and reduction of neonatal complications associated with preterm delivery. Most of the literature does not support the use of contraction inhibitors in patients with PPROM for longer than 48 h, believing that it may increase the chance of infection. However, studies have found that neonatal complications are mainly due to immaturity rather than infection. However, if the risk of infection exceeds the risk of preterm complications, termination of pregnancy should be considered. The process is “CVDD”: confirming the diagnosis, validating gestational age, documenting fetal wellbeing, and deciding on the mode of delivery. on the mode of delivery).
The size of the gestational week is the first factor that determines the management of PPROM. Since the principles of PPROM management developed by ACOG in 2007, PPROM has been classified according to the size of the gestational week as infertile PPROM (<23 gestational weeks), far from full term PPROM (23-31+6 gestational weeks), near full term PPROM (32-36 gestational weeks), and near full term PPROM as 32-33+6 and 34-36 weeks. Different management strategies were developed based on this classification (Table 1). It should be noted that because the level of treatment for preterm infants, especially the level of neonatal intensive care unit (NICU), varies greatly from region to region in China, after the occurrence of PPROM, obstetricians should weigh the risk of expectant treatment and preterm delivery according to maternal and child conditions such as gestational week size, presence of infection and fetal lung maturity, and the level of local NICU, and formulate the best management plan for mother and child The best management plan for mother and child or timely referral should be formulated based on the maternal and fetal status, including the size of the gestational week, the absence of infection and fetal lung maturity, and the local NICU level.
Table 1 Management of PPROM at different gestational weeks (infection, intrauterine distress and placental abruption have been excluded)
In the case of non-viable PPROM, because the fetus needs to continue the pregnancy for several weeks to obtain the possibility of survival, which is costly, and because of the high risk of maternal and fetal infection, it is mostly recommended not to continue the pregnancy and to induce labor, but the management should be individualized, with a comprehensive assessment of maternal and fetal risk factors to decide the treatment. If intraamniotic infectious (IAI), labor is imminent, or intrauterine condition is unclear, induction of labor should be considered first, regardless of whether the fetus will survive after birth; if none of the above occurs and the patient has a strong desire, close observation should be made to monitor temperature and signs of infection. In the absence of infection, fetal distress, placental abruption, etc., expectant treatment is feasible, but it depends on the level of NICU in the region, the ability and willingness of the pregnant woman. The expectant treatment includes: elevation of the buttocks, bed rest, avoidance of anal and vaginal examination, ultrasound dynamic monitoring of amniotic volume and fetal status, and vigilance for signs of placental abruption and amniotic cavity infection. Treatment with antibiotics, glucocorticoids and contraction inhibitors should be given.
Some complications, such as thrombosis, that may result from prolonged bed rest should be borne in mind. If clinical chorioamnionitis, fetal distress, placenta abruptio, or amniotic fluid deficiency persists for more than 10? d during the expectant treatment period, termination of pregnancy should be considered, while those with stable disease can expect termination of pregnancy after 34 weeks of gestation. In PPROM at 32 to 33+6 weeks of gestation, termination of pregnancy may be considered when there is evidence of fetal lung maturation; if the fetal lung is not mature, glucocorticoids and antibiotics may be given and the pregnancy may be terminated after 48 h of delivery or after 34 weeks of gestation. In PPROM at 34 to 36 weeks of gestation, the fetal lung is mature and expectant treatment may increase the incidence of maternal and fetal infection, and termination of pregnancy should be considered as soon as possible unless there is evidence of immature fetal lung.
I. Use of glucocorticoids
It is well established that a single course of glucocorticoid therapy has a great benefit on the prognosis of preterm infants with PPROM, and even a single dose of glucocorticoid given to a pregnant woman before preterm delivery can reduce the incidence of neonatal retinopathy, intraventricular hemorrhage, and neonatal death. The current domestic recommendation for glucocorticoids is dexamethasone 6 mg intramuscularly twice daily for 2 d. Abroad, betamethasone 12 mg intramuscularly once daily for 2 d. Although it is sometimes not given at the expected time and dose, it is beneficial as long as it has a 24-h in vivo duration of action. The best time to administer the drug is between 48 h and 7 d before delivery.
It is now believed that the glucocorticoid application regimen should be varied depending on the gestational week. Neonatal respiratory distress syndrome rarely occurs in PPROM at ≥34 weeks of gestation and therefore glucocorticoids should not be routinely administered unless there is evidence of fetal lung immaturity. It is still controversial whether glucocorticoids are routinely used in PPROM at 32-34 weeks of gestation. The majority of obstetricians in China recommend the routine use of glucocorticoids in PPROM at 32-34 weeks of gestation.
The NIH recommends a single course of glucocorticosteroid therapy for anyone at 24-34 weeks of gestation who is likely to have preterm labor. The current recommendation is still for a single course of glucocorticoid therapy. Repeated dosing does not improve neonatal outcomes, and multiple glucocorticoid injections may even result in fetal weight, brain weight, reduced organ volume, and abnormal neurological development, but there is a lack of evidence-based medical evidence. If a patient receives the drug for the first time at a small gestational week (before 32 weeks of gestation), does not deliver after giving a single course of glucocorticoids, and is still facing delivery at less than 34 weeks of gestational week, it has been suggested that additional single doses of rescue doses may be given beyond 32 weeks.
II. Use of contraction inhibitors
The purpose of using contraction suppressants in PPROM is to prolong the gestation time beyond 48-72 h, so that glucocorticoids can be given to promote fetal lung maturation. Thus, fetal lung maturation therapy is the key to improving the prognosis of the perinatal infant with PPROM, and contraction suppressants provide time for this therapy. The anti-contraction effect of contraction inhibitors has been increasingly recognized, and the effectiveness of contraction inhibitors for prolonging gestational age at delivery in PPROM has been increased to 2-7 d reported abroad and much more than that in China.
It is important to note that clinical use of contraction inhibitors is often excessive or too prolonged, even beyond 34 weeks and still in routine use, with a single-minded pursuit of the duration of expectant treatment. Be alert to the fact that the longer the duration of expectant treatment, the increased risks accompanying it, especially chorioamnionitis, neonatal pneumonia, and neonatal sepsis. However, for PPROM, although it has been suggested that the use of contraction inhibitors increases the risk of infection, the morbidity and mortality of early preterm infants or neonates born at less than 34 weeks is mainly brought about by premature immaturity rather than associated with infection, and therefore the use of contraction inhibitors is recommended for patients with PPROM at less than 34 weeks if there is no evidence of infection. There is no uniform limit on the low gestational age for the use of contraction inhibitors, except that the clinical use of Ritodrine ranges from 20 to 34 weeks.
Currently, contraction inhibitors are usually classified clinically into 6 major categories.
(1) β-agonists, represented by hydroxybenzylhydroephedrine and salbutamol;
(2) magnesium sulfate;
(3) prostaglandin synthetase inhibitors, the representative drug is indomethacin;
(4) calcium channel blockers, represented by nifedipine;
(5) contractin receptor antagonist; representative drug is atosiban;
(6) nitric oxide donor, such as nitroglycerin. But at present, the most widely used in China is still β agonists and magnesium sulfate. However, there are also contraindications to the application of uterine contraction inhibitors: contraindicated in placental abruption, severe pre-eclampsia and other unsuitable for expectant pregnancies, contraindicated in severe fetal malformations and chromosomal abnormalities, intrauterine infection, fetal distress and placental dysfunction, and contraindicated in PPROM gestational age up to 34 weeks fetal viability.
Therefore, before using PPROM, the specific conditions of the pregnant woman and the fetus should be evaluated to determine the course of PPROM, including the presence of maternal comorbidities and complications, signs of infection, intrauterine fetal safety, fetal development and the possibility of fetal survival. During the course of use, the mother and fetus should be closely monitored, and the advantages and disadvantages should be weighed to choose the most appropriate time to terminate the pregnancy, to improve the survival rate of the newborn, and to reduce complications.
III. Treatment of infection prevention
It is particularly important to strengthen the monitoring of chorioamnionitis, timely diagnosis of chorioamnionitis and timely termination of pregnancy for PPROM treatment. The presence of signs of IAI should be monitored for.
(1) Monitoring of pregnant women: taking temperature and pulse, monitoring the uterine body for pressure pain, the amount and smell of vaginal discharge, regular monitoring of blood picture and C-reactive protein, culture of group B streptococci and cervical flora, urine culture;
(2) assessment of fetal status: fetal heart and fetal movement count, ultrasound monitoring of amniotic fluid index, biophysical scoring, cord blood flow measurement, etc. The management of IAI focuses on monitoring the clinical course, interruption and timely and decisive termination of pregnancy. Once diagnosed, the pregnancy should be terminated immediately and timely management is the time to save the fetus clinically.
Prophylactic application of antibiotics for PPROM can prolong the incubation period of PPROM, reduce the incidence of infection in mother and child, and provide safety in anticipation of treatment. The prestigious National Institute of Child Health and Human Development multicenter trial proposed a standard antibiotic regimen for PPROM: ampicillin and erythromycin IV for 48 h followed by oral amoxicillin and entero-erythromycin for 5 d. Amoxicillin clavulanic acid potassium should be avoided as much as possible because of the possible increased risk of neonatal necrotizing small bowel colitis. In some pregnant women with PPROM who require prolonged expectant treatment, experts have recently asked if the duration of antibiotics can be shortened? but this needs to be supported by evidence from evidence-based medicine.?
IV. Cervical cerclage
Cervical cerclage is originally a procedure performed to prevent preterm delivery after pregnancy due to cervical laxity. When PPROM occurs after cervical cerclage, is the suture of the cervical cerclage released? Early studies suggested that keeping the cervical cerclage sutures in place after PPROM could prolong the incubation period but predispose to higher rates of IAI and neonatal infection. However, later studies found no difference in perinatal outcomes with or without release of the annuloplasty, and this study had insufficient specimen size, and a multicenter, larger sample size randomized controlled trial study is needed to assess this.
V. Mode of delivery
The choice of delivery method for PPROM is sometimes difficult, especially for PPROM between 28 and 32 weeks, and should be carefully evaluated by a combination of factors such as the chance of survival of the preterm infant, the presence of low amniotic fluid or chorioamnionitis, the length of labor, and the tolerance of contractions, etc. In patients with PPROM, either cesarean or vaginal delivery is an option, but obstetric practice should be followed, especially if the neonatal survival rate is estimated to be low Vaginal delivery should be chosen, especially if the survival rate of the newborn is estimated to be low or if labor is already imminent and the delivery is expected to end in a short time. In case of vaginal delivery, for the first time, an episiotomy should be made to reduce the resistance to the head. If the fetal position is abnormal (breech), a cesarean section should be performed. The choice of delivery method for very low birth weight infants needs to be determined on a case-by-case basis.
It is best to have a neonatologist present during delivery to prepare the newborn for asphyxia resuscitation. After delivery, attention should be paid to the first breath, tracheal intubation and ventilator if necessary, and early transfer to NICU.