Subclinical Histologic Chorioamnionitis and Related Clinical and Laboratory Parameters in Preterm Deliveries

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Provided by Elsevier - Publisher Connector Pediatr Neonatol 2009;50(5):217−221

ORIGINAL ARTICLE

Hui-Chung Wu1, Chung-Min Shen2*, Yih-Yiing Wu3, Yeong-Seng Yuh4, Ka-Em Kua2

1Department of Pediatrics, Cathay General Hospital, Hsin Chu, Taiwan 2Department of Pediatrics, Cathay General Hospital, Taipei, Taiwan 3Department of Pathology, Cathay General Hospital, Taipei, Taiwan 4Department of Pediatrics, Taitung St. Mary’s Hospital, Taitung, Taiwan

Received: May 31, 2008 Background: Histologic chorioamnionitis (HCA) is associated with preterm delivery Revised: Oct 9, 2008 and with neonatal morbidity and mortality. Because HCA is usually subclinical, his- Accepted: Jan 20, 2009 tologic examination of the placenta is essential for confirmatory diagnosis. In the present study, the correlations between subclinical HCA and relevant clinical and KEY WORDS: laboratory parameters were analyzed. C-reactive protein; Methods: This was a retrospective study. We reviewed the placental histopatho- logic findings and the charts of patients who were admitted to our neonatal intensive histologic care unit after delivery and their mothers between January 2007 and March 2008. A chorioamnionitis; total of 77 preterm infants [gastational age (GA): 32.2 ± 3.4 weeks, birth weight (BW): leukocytosis; 1,718 ± 554 g] were categorized as group A with histologic evidence of placental prolonged premature inflammation (n = 27) or group B without histologic evidence of placental inflamma- rupture of membrane tion (n = 50). Placental histology was studied to identify the presence of inflammatory states such as chorioamnionitis, funisitis and deciduitis. Laboratory parameters including complete blood count, differential count, and C-reactive protein (CRP) level of mothers and initial arterial blood gas, glucose level and mean blood pressure of the infants were documented. Gestational age, Apgar score, history of prolonged premature rupture of membrane (prolonged PROM), gestational diabetes mellitus, meconium- stained amniotic fluid, pregnancy-induced hypertension and signs of pre-eclampsia were also collected as clinical parameters. All data were analyzed using independent t tests and Fisher’s exact test, as appropriate. Results: Group A newborns had a significantly lower gestational age (30.8 ± 4.1 weeks vs. 33.0 ± 2.6 weeks, p < 0.05) and higher CRP level (0.56 ± 0.92 mg/dL vs. 0.12 ± 0.14 mg/dL, p < 0.05), together with higher maternal WBC count (13,002 ± 4,344/μL vs. 10,850 ± 3,722/μL, p < 0.05) and higher rate of prolonged PROM [14/27 (51.85%) vs. 8/37 (21.62%), p < 0.05] compared with group B newborns. Conclusion: We found that HCA was significantly correlated with lower gestational age, higher CRP level of preterm infants, higher maternal WBC count, and a higher rate of prolonged PROM. Our results demonstrate a significant association between HCA with an elevated CRP level in preterm infants. These findings further con- firmed the association between maternal inflammation and preterm deliveries.

*Corresponding author. Department of Pediatrics, Cathay General Hospital, No. 280, Jen-Ai Road, Section 4, Taipei, 106, Taiwan. E-mail: [email protected]

1. Introduction from sites with an overt abnormality. All tissue samples were cut into 1.5-μm-thick sections and Perinatal infections, such as chorioamnionitis, are stained with hematoxylin and eosin. The micro- well-known risk factors for spontaneous preterm scopic examination showed varying levels of inflam- delivery. With improvement in prenatal care, preg- mation in the amnion, chorion, subchorion, decidua, nant women with clinical presentations of chorio- intervillous spaces, extraplacental membranes, um- amnionitis are becoming less frequent. On the other bilical cord, and blood vessels. hand, subclinical chorioamnionitis has become more In this study, HCA was defined as diffuse infiltra- common.1−5 Thus, it is a important for clinicians to tion or aggregation of polymorphonuclear leukocytes reach an early diagnosis in these patients. in at least one high-power field of the chorioamnion In clinical practice, some preterm infants who plate. Inflammation in the decidua (deciduitis), um- have an unremarkable prenatal course and normal bilical cord (funisitis) and/or blood vessels (vascu- laboratory results are still suspected to have a peri- litis) was recorded. The severity of inflammation natal infection, even though the placental culture was classified as mild (focal), moderate or marked results are negative. The decision to start antibi- (with necrosis). otic treatment and determining the duration of The medical charts of the infants and their treatment depends on both the clinician’s experi- mothers were reviewed to retrieve complete blood ence and on the observation of the clinical course counts, differential leukocyte counts and C-reactive and manifestations. Without a confirmatory diagno- protein (CRP) level. The infants’ medical charts were sis of perinatal infection, overuse of antibiotics or reviewed for gestational age, Apgar score, initial inadequate antibiotic coverage is common in clini- arterial blood gas (< 24 hours), blood glucose level cal practice. and mean blood pressure. In addition, we also re- The placenta was once called the “diary of ges- viewed the prenatal history for presence of pro- tational life”, reflecting not only the intrauterine longed premature rupture of membrane (prolonged environment but also providing valuable information PROM; rupture of membrane > 18 hours), gestational on the cause and timing of many adverse events diabetes mellitus (GDM), meconium-stained amni- and conditions.6 However, because a large fraction otic fluid, pregnancy induced hypertension (PIH) of histologic chorioamnionitis (HCA) is subclinical,7,8 and pre-eclampsia. histologic examination of the placenta is essential Based on the reports of placental histology, 27 to confirm the diagnosis.2,9 Therefore, in the newborns (17 males and 10 females) were catego- present study, the correlations between subclinical rized into group A with histologic evidence of pla- HCA and relevant clinical and laboratory parame- cental inflammation and 50 (25 males and 25 ters were analyzed. females) into group B without histologic evidence of placental inflammation. Statistical analysis was performed to compare 2. Materials and Methods between group A and group B. Two-tailed Student’s t test was used to compare means and Fisher’s This retrospective study was conducted between exact test was used for categorical variables. A January 2007 and March 2008 at the neonatal inten- two-tailed p-value of < 0.05 was considered statis- sive care unit (NICU) of Cathay General Hospital. A tically significant. SPSS 12.0 software (SPSS Inc., total of 77 premature infants (42 males, 35 females; Chicago, IL, USA) was used. gestational age 32.2 ± 3.4 weeks, birth weight 1,718 ± 554 g) admitted to our NICU were enrolled in this study. There were 11 pairs of twins (3 pairs 3. Results were monochorionic−diamniotic, the others were dichorionic−diamniotic) and one triplet set (trichor- In this study, 27/77 (35.06%) preterm infants were ionic−triamniotic). classified into group A, which included 18 cases of All of the placentas of the enrolled patients were chorioamnionitis, four cases of deciduitis, one case fixed in formalin and then sent for gross examina- of funisitis accompanied with deciduitis, one case tion under the supervision of the same pathologist. of chorioamnionitis accompanied with deciduitis, Five tissue samples were taken from each placenta, and three cases of chorioamnionitis accompanied and were fixed in paraffin blocks. Tissue samples with funisitis. All of these cases were singletons. were taken from the site of cord insertion, the pla- The remaining 50 (64.94%) premature infants were centa margins, the middle part of the placenta, classified into group B, and included 11 pairs of the cord, and the extraplacental membranes. For as- twins and one triplet. Twenty-two of 64 (34.38%) sessment of normal and grossly abnormal placentas women had prolonged PROM. Fifty-three women of the twins and triplets, tissue samples were taken were screened for group B streptococcus (GBS) HCA and related parameters 219

Table 1 Maternal demographics and characteristics

Group A (n = 27) Group B (n = 37) p value Placenta inflammation (+) Placenta inflammation (−)

Age (yrs) 32.7 ± 3.5 32.1 ± 5.9 0.63 WBC (/μL) 13,002 ± 4,344 10,850 ± 3,723 0.037 Segments (%) 79.70 ± 7.42 75.72 ± 12.58 0.147 Lymphocytes (%) 13.62 ± 6.46 16.29 ± 7.84 0.152 Bands (%) 0.52 ± 2.31 1.35 ± 7.73 0.59 CRP (mg/dL) 2.10 ± 2.94 0.65 ± 0.94 0.51 Hb (g/dL) 11.23 ± 1.38 12.04 ± 1.90 0.68 Platelets (K/μL) 194.78 ± 40.08 183.39 ± 60.82 0.41

Values are expressed as means ± SD; p-values are for two-tailed Student’s t test; CRP = C-reactive protein; WBC = white blood cell count.

Table 2 Characteristics of preterm infants

Group A (n = 27) Group B (n = 50) p value Placenta inflammation (+) Placenta inflammation (−)

GA (wks) 30.8 ± 4.1 33.0 ± 2.6 0.04 BW (g) 1,633 ± 617 1,764 ± 518 0.326 Apgar score 1st min 6.33 ± 1.41 6.26 ± 2.17 0.875 Apgar score 5th min 8.00 ± 1.27 7.94 ± 1.78 0.877 WBC (/μL) 11,836 ± 7,365 9,770 ± 5,554 0.17 Segments (%) 42.77 ± 14.95 42.48 ± 16.49 0.938 Lymphocytes (%) 43.85 ± 16.42 46.74 ± 16.71 0.470 Bands (%) 0.7 ± 1.61 0.5 ± 1.01 0.499 Hb (g/dL) 15.76 ± 2.21 16.19 ± 2.00 0.388 Platelets (K/μL) 220.52 ± 64.08 220.72 ± 85.03 0.798 pH 7.256 ± 0.11 7.261 ± 0.10 0.846 pCO2 (mmHg) 57.14 ± 15.21 52.14 ± 11.53 0.111 pO2 (mmHg) 97.64 ± 43.18 101.92 ± 43.05 0.680 HCO3 (mEq/L) 24.19 ± 2.80 22.81 ± 4.08 0.125 BE (mEq/L) −3.86 ± 3.69 −4.70 ± 4.88 0.445 Saturation (%) 91.04 ± 13.89 93.51 ± 12.51 0.432 CRP (mg/dL) 0.56 ± 0.92 0.12 ± 0.14 0.025 Glucose (mg/dL) 62.22 ± 24.87 58.86 ± 23.37 0.559 MBP (mmHg) 39.44 ± 7.14 39.09 ± 7.12 0.837

Values are expressed as means ± SD; p-values are for two-tailed Student’s t test; BE = base excess; BW = birth weight; CRP = C-reactive protein; GA = gestation age; MBP = mean blood pressure; WBC = white blood cell count. before delivery, but only five (9.43%) had positive 0.12 ± 0.14 mg/dL, p = 0.025). The perinatal histo- vaginal GBS cultures. ries are shown in Table 3. There were no statistically Table 1 shows the maternal characteristics. The significant differences in terms of GDM, meconi- women in group A had significantly higher WBC um-stained amniotic fluid, PIH, maternal GBS cul- (group A 13,002 ± 4,344/μL vs. group B 10,850 ± 3,722/ ture results and pre-eclampsia between the two μL, p = 0.037). There were no statistically significant groups, except for prolonged PROM [group A 14/27 differences in terms of age, differential counts, (51.85%) vs. group B 8/37 (21.62%), p = 0.017]. hemoglobin concentration, platelet counts or CRP We also compared the placental histologic find- level. ings in terms of degeneration, calcification, hem- The characteristics of the preterm infants are orrhage, and infarction between the two groups and shown in Table 2. Infants in group A had a signifi- the initial neonatal outcomes such as congenital cantly lower gestational age (group A 30.8 ± 4.1 weeks pneumonia, intraventricular hemorrhage, patent vs. group B 33.0 ± 2.6 weeks, p = 0.04) and higher ductus arteriosus and neonatal seizure between CRP levels (group A 0.56 ± 0.92 mg/dL vs. group B the two groups. However, there were no statistically 220 H.C. Wu et al

Table 3 Perinatal history

Group A (n = 27) Group B (n = 50) p value Placenta inflammation (+) Placenta inflammation (−)

PIH, n (%) 1/27 (3.7%) 7/37 (18.91%) 0.124 Preeclampsia, n (%) 1/27 (3.7%) 5/37 (13.51%) 0.338 GDM, n (%) 2/26 (7.69%) 4/36 (11.11%) 1.0 Prolonged PROM, n (%) 14/27 (51.85%) 8/37 (21.62%) 0.017 APH, n (%) 3/27 (11.11%) 8/37 (21.62%) 0.331 Placenta abruptia, n (%) 4/27 (14.81%) 10/37 (27.02%) 0.36 Placenta previa, n (%) 1/27 (3.7%) 8/37 (21.62%) 0.67 Uterus abnormal, n (%) 2/27 (7.4%) 0/37 ( − ) 0.174 Fetal distress, n (%) 7/27 (25.92%) 16/48 (33.33%) 0.606 Maternal GBS (+), n (%) 3/22 (13.64%) 2/31 (6.45%) 0.638 Meconium stain, n (%) 3/27 (11.11%) 6/50 (12%) 1.0

Values are expressed as numbers (percentage); p-values are for Fisher’s exact test; APH = ante partum hemorrhage; GBS = group B streptococcus; GDM = gestational diabetes mellitus; PIH = pregnancy induced hypertension; PROM = premature rupture of membrane. significant differences in terms of histologic find- A full 7−10-day course of antibiotics should be given ings or initial neonatal outcomes between the two in symptomatic preterm infants with elevated CRP groups. Furthermore, the singleton infants and mul- levels whose mothers had PROM and a higher WBC tiple gestations in group B did not differ statisti- count. Which should subsequently involve discon- cally, except for body weight at birth and WBC in tinuation of antibiotics, and the patient should preterm infants. be closely monitored. Pacora et al proposed that the fetal plasma IL-6 concentration is significantly associated with the presence of inflammatory le- 4. Discussion sions in the extraplacental membranes and umbilical cord. They suggested that funisitis and chorionic In our study, none of the pregnant women in group vasculitis are histological manifestations of the A were diagnosed with chorioamnionitis by clinical fetal inflammatory response syndrome (FIRS). This criteria, which included fever (body tempera- subclinical condition is characterized by elevated ture > 37.8ºC) plus two or more of the following: proinflammatory cytokine levels in the fetal circu- maternal tachycardia (> 100 beats/min), fetal tachy- lation and multiple organ dysfunction, and is a risk cardia (> 160 beats/min), uterine tenderness, mal- factor for adverse neonatal outcomes.11 The pla- odorous or cloudy amniotic fluid, maternal WBC cental pathological findings in our study were con- counts > 15,000 cells/mm3, and with no other focus sistent with FIRS, as described in Pacora’s report. of infection.10 Other reports have revealed that In our study, no significant differences in neonatal the incidence of HCA is much higher than that of outcomes were observed between the two groups. clinically diagnosed infection, and the correlation However, many other sources are linked to subclini- between these entities is poor.1−5 Chorioamnionitis cal infection in preterm delivery and serious neona- can be easily overlooked and undiagnosed, partic- tal sequelae, such as periventricular leukomalacia, ularly if placenta histologic examination is not cerebral palsy, respiratory distress, bronchopulmo- performed. nary dysplasia and necrotizing enterocolitis.5,7,12−14 Treatment with antibiotics in cases of perinatal The limitations of our study are the small sample infection is usually inadequate because of the po- size and the short duration of observation. Mu et al tential for inaccurate diagnosis and unreliable followed up very-low-birth-weight infants with cho- parameters. There are currently no treatment strat- rioamnionitis until the corrected age of 24 months egies to manage symptomatic preterm infants from old and concluded that there was no significantly mothers with subclinical chorioamnionitis. The re- increased risk of lower Mental Development Index or sults of our study revealed that subclinical HCA was Psychomotor Developmental Index scores between significantly associated with a higher rate of pro- the chorioamnionitis group and the non-chorioam- longed PROM, lower gestational age, higher maternal nionitis group.15 On the other hand, several recent WBC count, and elevated CRP level in preterm infants. studies support the hypothesis that intrauterine Our study identified the most reliable parameters infection with a fetal inflammatory response results for the diagnosis of subclinical chorioamnionitis. in the production of proinflammatory cytokines, HCA and related parameters 221 which are directly responsible for white matter dam- 2. Felice CD, Toti P, Parrini S, et al. Histologic chorioamnionitis age and cerebral palsy in preterm infants.16−18 There- and severity of illness in very-low-birth-weight newborns. Pediatr Crit Care Med 2005;6:298−302. fore, more studies are required to evaluate the 3. Gibbs RS, Duff P. Progress in pathogenesis and management association between subclinical histologic chorio- of clinical intraamniotic infection. Am J Obstet Gynecol amnionitis and neurologic outcomes. 1991;164:1317−26. With the increasing rate of medical malpractice 4. Saini S, Goel N, Sharma M, Arora B, Garg N. C-reactive pro- litigation for cerebral palsy, placental pathology teins as an indicator of sub-clinical infection in cases of premature rupture of membranes. Indian J Pathol Microbiol not only provides objective evidence for clinically 2003;46:515−6. suspected cases of perinatal infection but also sup- 5. Hermansen MC, Hermansen MG. Perinatal infections and ports clinical decisions for its management. Based cerebral palsy. Clin Perinatol 2006;33:315−33. on our findings, histological examination of the pla- 6. Baergen RN. The placenta as witness. 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