METHODS
This prospective cohort study was conducted in the Department of Obstetrics and Gynaecology in University College of Medical Sciences and Guru Teg Bahadur Hospital, Dilshad Garden, New Delhi, India.
All women with a singleton pregnancy diagnosed with PPROM at gestational age 28 + 0 to 33 + 6 weeks between November 2018 and April 2020 were recruited. Gestational age was calculated using first day of last menstrual and confirmed by ultrasonographic dating. Women who went in spontaneous labor within 48 hours of PPROM or those with medical or obstetric pregnancy complications, or with congenital malformation in fetus were excluded from the study.
Diagnosis of PPROM was made by demonstrating vaginal pooling on sterile speculum examination and/or the pH evaluation of fluid collected from the posterior vaginal fornix. Following the diagnosis, expectant management was instituted as per the institutional protocol. Tablet erythromycin (250 mg) was given orally every 6 hour for 10 days. Injection betamethasone was given 12mg, two dose, 24 hour apart for lung maturity. Patient was kept on conservative management till completed 34 weeks or if she develop features of clinical chorioamnionitis or abruptio placentae, or in case of non-reassuring fetal status. Patient was observed for signs and symptoms of chorioamnionitis. Fetal surveillance was done by daily fetal movement count, non stress test and biophysical profile. Clinical chorioamnionitis was defined as presence of fever ≥ 37.8° C along with two or more of following, i.e. maternal leukocytosis (TLC > 15000 cells/mm3), maternal tachycardia (heart rate > 100 beats/min), fetal tachycardia (fetal heart rate > 160 beats/min), uterine tenderness and foul smelling discharge.
All patients were subjected to ultrasonographic examination within 48 hours of admission. Various parameters such as presentation, placental localization, amniotic fluid index, effective fetal weight were noted. Fetal urine production rate was calculated by doing serial fetal bladder volume measurements at an interval of 10 minutes. Bladder volume was measured on E-cube 7, Alpinion Medical Systems, BPL using a 1.0-6.0 MHz C1-6 convex array probe. Fetal bladder was first localized and focused in two planes and measurements of anteroposterior diameter (i.e. length), transverse diameter (i.e. width) and craniocaudal diameter (i.e. height) were noted, and bladder volume was generated by formula given by Campbell et al5 i.e.
Bladder volume =\(\frac{4}{3}\times\pi\times diameter\frac{a}{2}\times diameter\frac{b}{2}\times diameter\frac{c}{2}\)Diameter a: anteroposterior diameter Diameter b: transverse diameter Diameter c: craniocaudal diameter
Bladder volume was measured 3 times ultrasonographically at an interval of 10 minutes and fetal urine production rate (FUPR) was assessed by change in fetal bladder volume over time. If the second value comes out to be less than the first value as might occur with fetal voiding, then the first value was discarded and the second value was taken as initial measurement and two more values were estimated. Two values of FUPR were calculated and the mean of the resulting two values was taken. The FUPR was measured weekly till the patient delivered and the last measured FUPR was used for analysis. The FUPR was compared with the gestational age specific nomograms as given by Rabinowitz et al6. FUPR was considered reduced if the value was less than the 5th percentile value of FUPR for that gestational age. FUPR was considered normal if it falls between 5th and 95th percentile values for that age.
At the time of delivery, 2ml cord blood sample was taken in EDTA container for measuring Interleukin-6 (IL-6) levels. The blood was centrifuged and the separated plasma was stored at -80°C till estimation of IL-6 levels (Diaclone IL-6 ELISA kit as per manufacturer’s direction). The lower and upper detection limit for measurement of IL-6 levels were 1 and 200pg/ml. Some of our values of IL-6 levels were more than 200 even after putting dilution. So, we had taken those values as 200 for the calculation of mean of IL-6 levels. Placental membrane and cord tissue were collected and stored at room temperature in 10% formalin and was sent for histopathological examination to look for features suggestive of FIRS. Placental membrane was also sent for bacteriological cultures. FIRS is defined by elevated IL-6 levels in cord blood or presence of characteristic histologic features of placenta which includes funisitis and chorionic vasculitis.
Neonates were assessed by pediatrician at birth and shifted to NICU as per hospital protocol. Maternal outcomes were studied for delivery outcome, postpartum complications. Neonates were followed up and neonatal outcomes were noted as admission to NICU, duration of NICU stay and neonatal morbidity. Severe neonatal morbidity was defined as development of early onset neonatal sepsis (within 72hour), respiratory distress syndrome, bronchopulmonary dysplasia, periventricular leukomalacia, necrotizing enterocolitis or intraventricular hemorrhage.
All the procedures performed in this study on human participants were in accordance with the ethical standards of the institutional research committee (IEC-HR/2018/36/76R, dated 26/10/2018). Written Informed consent was obtained from all the individual participants included in the study. The study was funded solely by institutional funds – Intramural grant from University College of Medical Sciences, New Delhi, India.