Abstract
Objective
To compare the sensitivity and specificity of leukocyte esterase activity (LEA) to histopathological examination in diagnosing chorioamnionitis.
Methods
We compared the diagnostic tests performed at Dr. Mohammad Hoesin Hospital, Palembang, Indonesia, from September 2015 to April 2016. Ninety-one pregnant women were included in the study. The LEA and histopathological examination were carried out with neonatal sepsis the main outcome. Data were analyzed using the SPSS version 21.0 and MedCalc statistics.
Results
Chorioamnionitis was detected in 54 (77.1%) patients with a gestational age ≥37 weeks and in 16 (22.9%) patients with a gestational age <37 weeks. The duration of membrane rupture was significantly associated with chorioamnionitis (P = 0.001 and P = 0.011). Neonatal sepsis was also significantly associated with chorioamnionitis in both groups (P = 0.014 and P = 0.036). A LEA value with the cut-off point >0.5 was able to significantly predict chorioamnionitis with 98.6% sensitivity and 95.2% specificity, providing better accuracy in diagnosing chorioamnionitis in the preterm pregnancy group.
Conclusion
LEA had a very good predictive value for chorioamnionitis with better accuracy in diagnosing chorioamnionitis in preterm pregnancy.
Introduction
Chorioamnionitis or infection of the fetal membranes is defined as an inflammation or infection in the placenta, amnion and/or chorion [1]. About 1–4% of the deliveries in the United States are complicated by chorioamnionitis. Chorioamnionitis is found as a complication in 40–70% of preterm deliveries with preterm premature rupture of membranes and is found in 1–13% of term deliveries [2], [3].
The risk factors of chorioamnionitis are young age, a longer duration of preterm rupture of membranes, nulliparity, low socioeconomic status, multiple vaginal examinations, prolonged internal fetal monitoring, bacterial vaginosis, streptococcus group B colonization, and meconium aspiration. Chorioamnionitis diagnosis is established by the use of clinical, laboratory and histopathologic criteria. Using the clinical and laboratory reference values, chorioamnionitis symptoms and signs include maternal fever reaching more than 38°C or 100.4°F, and any one of the following criteria: maternal leukocytosis (leukocyte >15,000/mm3), maternal tachycardia (>100/min), persistent fetal tachycardia (>160/min), abdominal pain, atonic uterus and cloudy and purulent amniotic fluid with foul odor [1], [2], [4].
Chorioamnionitis may give rise to serious consequences for the mother and fetus. Maternal complications of chorioamnionitis are heightened delivery risk with a cesarean-section, infected delivery wound, pelvic abscess, bacteremia, and postpartum bleeding. In about 10% of mothers with chorioamnionitis a positive blood culture was related to streptococcus group B and Escherichia coli infection, although late complications from this bacteremia are rarely found. Different from maternal complications, chorioamnionitis fetal complications may prove fatal and include meningitis (3%), necrotizing enterocolitis [4], [5], [6] pneumonia (10–21%), sepsis (7–28%), intracranial hemorrhage (22–24%) and respiratory distress syndrome (62–63%) with mortality reaching about 25%. Long-term complications in neurologic development, such as cerebral palsy, may also be related to chorioamnionitis [1], [5], [7], [8].
One of the challenges in diagnosing chorioamnionitis is the lack of an ideal biomarker to help in establishing the diagnosis. Early detection of chorioamnionitis in patients with premature rupture of membranes or preterm premature rupture of membranes will be very helpful in patient management to decrease perinatal morbidity and mortality. The leukocyte esterase activity (LEA) examination is one of the available dipstick test used in diagnosing a urinary tract infection (UTI) [9], [10]. Now, LEA is also used to diagnose lower genital tract infections. Leukocyte esterase is released by polymorphonuclear cells as a response to infection, this enzyme then reacts with the components in the dipstick which hydrolyzes indoxyl carboxylic acid ester into indoxyl which further reacts with diazonium salt, producing a purple color on the dipstick [10], [11].
Hoskins et al. in their study on LEA in the early detection of chorioamnionitis found that LEA, as a predictor of chorioamnionitis, had a sensitivity, specificity, positive predictive value and negative preditive value of 91, 95, 95, and 91%, respectively [9], [10], [11].
Histopathologic chorioamnionitis diagnosis is focused on the identification of neutrophils on the membrane – this finding is still considered the gold standard in establishing the chorioamnionitis diagnosis [12], [13]. All of these prompted us to compare LEA with histopathological examination in chorioamnionitis and the outcome of perinatal infection.
Methods
This study was a comparative study which involved 91 pregnant women. We conducted this study in the Obstetrics and Gynaecology Department of Dr. Mohammed Hoesin General Hospital, Palembang, Indonesia, from September 2015 to April 2016.
Inclusion criteria were women with singleton, live pregnancy ≥22 weeks, premature rupture of membranes, not in labor or in the latent phase of delivery (cervical dilatation when admitted <4 cm), all parity and suspected chorioamnionitis who consented to be recruited into our study by signing a written informed consent.
Exclusion criteria for our study were a twin pregnancy, hypertension in pregnancy, infectious diseases due to systemic disorder, vaginal bleeding excluding bloody show, fetal distress, a dead fetus and a history of amniocentesis or chorionic villous sampling.
Basic data were collected from all patients fulfilling the inclusion criteria. These data included identity, gestational age, parity, education level, occupation, smoking record, physical examination results, obstetrics examination results, nitrazin test result, LEA examination results and record of delivery. After delivery, a neonatal examination was carried out, starting from identity, gender, body weight, birth length, APGAR score and a physical and laboratory examinations to identify neonatal sepsis. A placental histopathological examination was also carried out which included the maternal chorion, amnion membrane, umbilical cord and fetal chorion to determine chorioamnionitis histologically according to the Salafia criteria.
Data were analyzed using the SPSS version 21.0 (IBM, Armonk, NY, US). Descriptive data were analyzed using the Pearson chi-squared (χ2) test, and Fisher’s exact test and the χ2-test. The cut-off point for LEA was displayed using a receiving operating characteristic (ROC) curve. The sensitivity, specificity, positive predictive value, negative predictive value and likelihood ratio were calculated using the MedCalc statistics.
Results
Demographic characteristics
The demographic characteristics of the study samples are illustrated in Table 1. From Table 1, it is clear that the majority of subjects in both groups were in the age group of 20–35 years (81.4% and 85.7%) which is an ideal reproductive age range; the majority of women had term pregnancies (77.1% and 85.7%); most of the women were primigravida (52.9% and 52.4%) most of the subjects were private sector employees (94.3% and 85.7%); most of the subjects were high school educated (54.3% and 61.9%) and there was no subject with a smoking habit. Using the χ2 analysis, no significant difference was found between the two groups in all these variables. This showed that chorioamnionitis in pregnant women with premature rupture of membranes was not influenced by the demographic characteristics in both groups.
Characteristics | Chorioamnionitis (+) |
Chorioamnionitis (−) |
|||
---|---|---|---|---|---|
n | % | n | % | P-value | |
Maternal age (years) | |||||
<20 | 2 | 2.9 | 1 | 4.8 | 0.724c |
20–35 | 57 | 81.4 | 18 | 85.7 | |
>35 | 11 | 15.7 | 2 | 9.5 | |
Gestational age (weeks) | |||||
<37 weeks | 16 | 22.9 | 3 | 14.3 | 0.545b |
≥37 weeks | 54 | 77.1 | 18 | 85.7 | |
Parity | |||||
Nulliparity | 37 | 52.9 | 11 | 52.4 | 0.582a |
Multiparity | 33 | 47.1 | 10 | 47.6 | |
Occupation | |||||
Private sector | 66 | 94.3 | 18 | 85.7 | 0.346b |
Civil servant | 4 | 5.7 | 3 | 14.3 | |
Education | |||||
Primary school | 6 | 8.6 | 0 | 0 | 1c |
Junior high school | 21 | 30 | 3 | 14.3 | |
Senior high school | 38 | 54.3 | 13 | 61.9 | |
Diploma | 1 | 1.4 | 4 | 19 | |
Bachelor degree | 4 | 5.7 | 1 | 4.8 | |
Smoking habit | |||||
Yes | 0 | 0 | 0 | 0 | 1c |
No | 70 | 100 | 21 | 100 |
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aχ2-test, P = 0.05; bFischer’s exact test, P = 0.05; cPearson χ2, P = 0.05.
Influence of the duration of preterm rupture of membranes in chorioamnionitis
Table 2 shows that in both groups of preterm rupture of membranes (term and preterm pregnancy), the duration of preterm rupture of membranes significantly (P = 0.001 and P = 0.011) influenced chorioamnionitis, where a longer period of premature rupture of membranes significantly induced more cases of chorioamnionitis.
Chorioamnionitis | PROM duration (h) | PPROM duration (h) | P-value |
---|---|---|---|
(+) | 29.8333 ± 54.14821 | 15.3125 ± 19.1406 | 0.103 |
(−) | 3.3333 ± 1.90973 | 1.3333 ± 0.57735 | 0.004 |
P-value | 0.001 | 0.011 |
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PROM, Premature rupture of membrane; PPROM, preterm premature rupture of membrane. Independent t-test, 95% confidence interval (CI).
Table 2 also shows that in those having chorioamnionitis, premature rupture of membranes in the term pregnancy group had a longer mean compared to the preterm pregnancy group (29.8 h vs. 15.3 h), showing that preterm premature rupture of membranes may quickly develop a complications – i.e. chorioamnionitis – compared to premature rupture of membranes in term pregnancies.
Association between chorioamnionitis and neonatal outcome
Most neonates from mothers with term pregnancies, preterm rupture of membranes and chorioamnionitis (57.4%) had developed sepsis; meanwhile, most neonates from mothers with term pregnancies, preterm rupture of membranes and no chorioamnionitis (77.8%) had not developed sepsis. Statistically, there was a significant association between neonatal sepsis and maternal chorioamnionitis, with an odds ratio (OR) 4.717 (1.372–16.223) which illustrated that mothers with term pregnancies with preterm rupture of membranes and chorioamnionitis had 4.717 times more risk for neonates to be diagnosed with sepsis compared to mothers with term pregnancies with preterm rupture of membranes but no chorioamnionitis. Similar to term pregnancies with premature rupture of membranes, all (100%) mothers with preterm pregnancies and premature rupture of membranes without chorioamnionitis had neonates with no sepsis. Statistically, there was a significant association between chorioamnionitis in mothers with preterm premature rupture of membranes and neonatal sepsis.
Cut-off point for the LEA examination in chorioamnionitis diagnosis
The LEA cut-off point as high as 0.5 with 98.6% sensitivity and 95.2% specificity significantly predicted chorioamnionitis diagnosis (P < 0.001) with a very high predictive value [area under the curve (AUC) 0.985] (Figure 1).
Comparison of LEA test to histopathology examination in diagnosing chorioamnionitis
Chorioamnionitis | Sensitivity (%) | Specificity (%) | PPV (%) | NPV (%) | Accuracy (%) |
---|---|---|---|---|---|
Term pregnancy | |||||
Maternal chorion | 77.6 | 60 | 96.26 | 16.67 | 76.38 |
Amniotic fluid | 78.12 | 50 | 92.6 | 22.22 | 75 |
Umbilical cord | 76.19 | 33.33 | 88.89 | 16.67 | 70.83 |
Fetal chorion | 75 | 75 | 83.33 | 16.67 | 66.67 |
Preterm pregnancy | |||||
Maternal chorion | 84.2 | 100 | 100 | 0 | 84.2 |
Amniotic fluid | 88.89 | 100 | 100 | 33.3 | 89.47 |
Umbilical cord | 83.33 | 0 | 93.75 | 0 | 78.95 |
Fetal chorion | 84.21 | 100 | 100 | 0 | 84.21 |
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PPV, Positive predictive value; NPV, negative predictive value.
Table 3 demonstrated the diagnostic value of LEA for establishing chorioamnionitis in both groups. The accuracy rate of LEA was found to be better in diagnosing chorioamnionitis in the preterm pregnancy group.
Discussion
Chorioamnionitis is still considered a serious infection problem which has maternal and fetal impacts. Chorioamnionitis induces preterm labor which in turn puts the neonate at a high-risk of sepsis or even perinatal death. Problems regarding chorioamnionitis do not only involve complications arising from chorioamnionitis but also involve increased ability in the early detection of chorioamnionitis using cheap, reliable and non-invasive tools.
Our study illustrated that chorioamnionitis in pregnant women with preterm rupture of membranes was not influenced by the demographic characteristics. Nordenvall and Sandstedt [14] also found similar results in which there were no differences in age, gestational age, parity and smoking habit which may influence chorioamnionitis. In their study, Nordenvall and Sandstedt [14] found the mean subject age to be 29 years, gestational age to be 39 weeks and most were primigravida. Erdemir et al. [15] also found similar results in their study where chorioamnionitis was not influenced by maternal age – in which mean maternal age was found to be 30.1 ± 6.9 years. In their study, Erdemir et al. showed that there was no association between chorioamnionitis and maternal socioeconomic status – there was a similar percentage of mothers with good socioeconomic status without chorioamnionitis (66.7%) and those with poor socioeconomic status without chorioamnionitis (33.3%).
Different findings were discovered in a study by Chan et al. [16] in Bangladesh in which it was found that chorioamnionitis was affected by maternal occupation – in this study, subjects working as construction workers and janitors were 1.69 times more likely to have chorioamnionitis.
In our study, demographics revealed that there were 54 subjects (77.1%) with term pregnancies and 16 subjects (22.9%) with preterm pregnancies in whom chorioamnionitis was diagnosed. In contrast with our study, Erdemir et al. [15] found that chorioamnionitis was more likely to be encountered in preterm pregnancies with a mean gestational age of 27.5 ± 2.5 weeks (P < 0.01).
Chorioamnionitis has been histopathologically defined in our study as having four positive findings in the placental samples according to the Salafia criteria. We found that the duration of premature rupture of membranes significantly influenced the chorioamnionitis diagnosis, in other words, a prolonged period of premature rupture of membranes significantly associated with more chorioamnionitis cases. Our study also illustrated that preterm premature rupture of membranes were complicated sooner by chorioamnionitis than premature rupture of membranes in term pregnanies. A similar finding was also reported by Popowski et al. [17] in 2011; they showed that premature rupture of membranes in pregnancy <37 weeks were having a 1.1 times greater risk of developing chorioamnionitis proven histologically than in pregnancy ≥37 weeks with a mean period of rupture of membranes 25 h from admission to delivery.
Findings regarding the latency of rupture of membranes (interval between rupture of membranes and delivery) were discovered by Patil and Patil [18] in their study about maternal and fetal outcomes in preterm premature rupture of membranes. Patil and Patil [18] found that the amniotic membranes in preterm pregnancies were more likely to have pathologic defects which would cause a higher pressure compared to term pregnancy – this would be indirectly associated with the latency period. Patil and Patil [18] further stated that there was an inverse correlation between gestational age and the duration of latent period, i.e. in those with younger gestational age, the latent period would be longer, hence, chorioamnionitis incidence would be higher in preterm pregnancy compared to term pregnancy.
The hypothesis stating that chorioamnionitis in term pregnancy with premature rupture of membranes required a longer duration of rupture compared to preterm premature rupture of membranes was a coincidence. This was supported statistically by an insignificant P-value found (P = 0.013). The calculation of the duration of rupture of membranes in preterm pregnancy which was started from a failed conservative management also influenced our results. We recommended a larger sample size for future studies to address the high variability in term pregnancy with premature rupture of membranes to produce a significant finding.
In our study, there was a significant association between chorioamnionitis and neonatal sepsis in both term and preterm pregnancy groups. Statistically, there were 31 subjects (57.4%) with term pregnancy and 12 subjects (75%) with preterm pregnancy developing neonatal sepsis.
A study by Rodrigo et al. [19] in 2013 illustrated a significant association between early onset neonatal sepsis and maternal chorioamnionitis (adjusted relative risk = 6.13; 95% confidence interval (CI) = 1.67–2.58; P = 0.006) and between periventricular leukomalacia and maternal chorioamnionitis (adjusted relative risk = 24.62; 95% CI = 1.87–324.28; P = 0.015). Similar findings in a previous study, i.e. significant association between chorioamnionitis and high incidence of premature rupture of membranes, sepsis, bronchopulmonary dysplasia, and a longer mechanical ventilator use were found by Mu et al. [20] in 2008.
The accuracy rate of LEA was found to be better in diagnosing chorioamnionitis in the preterm pregnancy group. A difference in the accuracy rate in the two groups for establishing chorioamnionitis by using these two instruments may be caused by several factors. The small sample size and the possibility of other primary infections could not be controlled by us. Though in our study, we conducted a robust patient screening, we also performed history taking, physical examination, obstetrics examination and laboratory examination to exclude potential primary infection which may induce a bias in our study.
Conclusions
There was a significant association between the duration of rupture of membranes, neonatal sepsis and chorioamnionitis – i.e. preterm premature rupture of membranes sooner developed complications compared to premature rupture of membranes in term pregnancy. The LEA examination had a very encouraging predictive value in chorioamnionitis cases with a better accuracy rate found in establishing chorioamnionitis in the preterm pregnancy group.
Recommendation
Further study regarding the accuracy of the LEA examination with a larger sample size and improved effort in controlling the other primary infections is needed to reach a more refined result.
Author’s Statement
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Conflict of interest: Authors state no conflict of interest.
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Material and methods: Informed consent: Informed consent has been obtained from all individuals included in this study.
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Ethical approval: The research related to human use has been complied with all the relevant national regulations, institutional policies and in accordance the tenets of the Helsinki Declaration, and has been approved by the authors’ institutional review board or equivalent committee.
References
[1] Tita AT, Andrews WW. Diagnosis and management of clinical chorioamnionitis. Clin Perinatol. 2010;37:339–54.10.1016/j.clp.2010.02.003Search in Google Scholar
[2] Edwards RK. Chorioamnionitis and labor. Obstet Gynecol Clin N Am. 2005;32:287–96.10.1016/j.ogc.2004.12.002Search in Google Scholar
[3] Czikk NJ, McCharty FP, Murphy KE. Chorioamnionitis: from pathogenesis to treatment. Clin Microbiol Infect. 2011;17:1304–11.10.1111/j.1469-0691.2011.03574.xSearch in Google Scholar
[4] Riggs JW, Blanco JD. Pathophysiology, diagnosis, and management of intraamniotic infection. Sem Perinatol. 1998;22:251–9.10.1016/S0146-0005(98)80013-XSearch in Google Scholar
[5] Fishman SG, Gelber SE. Evidence for the clinical management of chorioamnionitis. Sem Fetal Neonatal Med. 2012;17:46–50.10.1016/j.siny.2011.09.002Search in Google Scholar
[6] Holzman C, Lin X, Senagore P, Chung H. Histologic chorioamnionitis and preterm delivery. Am J Epidemiol. 2007;166:786–94.10.1093/aje/kwm168Search in Google Scholar
[7] Gordon A, Lahra M, Greenow C, Jeffrey H. Histological chorioamnionitis is increased at extremes of gestation in stillbirth: a population-based study. Inf Dis Obstet Gynecol. 2011;2011:1–7.10.1155/2011/456728Search in Google Scholar
[8] Thomas W, Speer CP. Chorioamnionitis: important risk factor or innocent for neonatal outcome. Neonatology. 2011;99:177–87.10.1159/000320170Search in Google Scholar
[9] Hoskins IA, Commander MC, Johnson TR, Winkel CA, Colonel MC. Leukocyte esterase activity in human amniotic fluid for the rapid detection of chorioamnionitis. Am J Obstet Gynecol. 1987;157:730–2.10.1016/S0002-9378(87)80039-XSearch in Google Scholar
[10] Gauthier DW, Meyer WJ. Comparison of gram stain, leukocyte esterase, and amniotic fluid glucose concentration in predicting amniotic fluid culture results in preterm premature rupture of membranes. Am J Obstet Gynecol. 1992;167:1092–5.10.1016/S0002-9378(12)80044-5Search in Google Scholar
[11] Hoskins IA, Katz J, Ordorica SA, Young BK. Esterase activity in second-and third-trimester amniotic fluid: an indicator of chorioamnionitis. Am J Obstet Gynecol. 1989;161:1543–5.10.1016/0002-9378(89)90922-8Search in Google Scholar
[12] Salafia CM, Weigl C, Silberman L. The prevalence and distribution of acute placenta inflammation in uncomplicated term pregnancies. Obstet Gynecol. 1989;73(3Pt1):383–98.10.1016/0020-7292(89)90252-XSearch in Google Scholar
[13] Redlines RW. Inflammatory responses in acute chorioamnionitis. Seminars Fetal Neonat Med. 2012;17:20–5.10.1016/j.siny.2011.08.003Search in Google Scholar
[14] Nordenvall M, Sandstedt B. Chorioamnionitis in relation to gestational outcome in a Swedish population. Eur J Obstet Gynecol Reprod Bio. 1990;36:59–67.10.1016/0028-2243(90)90050-BSearch in Google Scholar
[15] Erdemir G, Kultursaya N, Calkavur S, Zekio O, Koruglu O, Cakmak B, et al. Histological chorioamnionitis: effects on premature delivery and neonatal prognosis. Ped Neonatol. 2013;54:267–74.10.1016/j.pedneo.2013.03.012Search in Google Scholar
[16] Chan GJ, Silverman M, Zaman M, Murillo-Chaves A, Mahmud A, Baqui AH, et al. Prevalence and risk factors of chorioamnionitis in Dhaka, Bangladesh. J Perinatol. 2016;36:1039–44.10.1038/jp.2016.150Search in Google Scholar
[17] Popowski T, Goffinet F, Maillard F, Schmitz T, Leroy S, Kayem G. Maternal markers for detecting early-onset neonatal infection and chorioamnionitis in cases of premature rupture of membranes at or after 34 weeks of gestation: a two-center prospective study. BMC Pregnancy Childbirth. 2011;11:1–9.10.1186/1471-2393-11-26Search in Google Scholar
[18] Patil S, Patil V. Maternal and foetal outcomes in premature rupture of membranes. IOSR J Dental Med Sci. 2013;13:56–83.10.9790/0853-131275683Search in Google Scholar
[19] Rodrigo F, Gloria M, Henrıquez M, Ospina C. Morbidity and mortality among very-lowbirth-weight infants born to mothers with clinical chorioamnionitis. Ped Neonatol. 2014;55:381–6.10.1016/j.pedneo.2013.12.007Search in Google Scholar
[20] Mu SC, Lin CH, Chen YL, Ma HJ, Lee JS, Lin MI. Impact on neonatal outcome and anthropometric growth in very low birth weight Infants with histological chorioamnionitis. J Formos Med Assoc. 2008;107:304–10.10.1016/S0929-6646(08)60091-1Search in Google Scholar
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