A pregnancy-specific reference interval for procalcitonin

Diagnostic value of Procalcitonin, C-reactive protein-to-lymphocyte ratio (CLR), C-reactive protein and neutrophil-to-lymphocyte ratio (NLR) for predicting patients with Bacteraemia in the intensive care unit

BACKGROUND

To explore the diagnostic value of procalcitonin (PCT), C-reactive protein-to-lymphocyte ratio (CLR), C-reactive protein (CRP) and neutrophil-to-lymphocyte ratio (NLR) for predicting patients with bacteremia in the intensive care unit (ICU).

METHODS

This case-control study included 359 patients with suspected bacteremia were divided into a bacteremia group (n = 152) and a control group (n = 207) from September 2018 to April 2023. Patient data were collected using a laboratory information system (LIS). ROC curves for PCT, CLR, CRP, and NLR in predicting patients with bacteremia.

RESULTS

For PCT, CLR, CRP and NLR to predict patients with bacteremia in the ICU, the AUCs were 0.991(95%CI: 0.974-0.998), 0.960(95%CI: 0.935-0.978), 0.955(95%CI: 0.928-0.974), and 0.898(95%CI:0.862-0.927), respectively; the optimal thresholds were 0.248 ng/mL, 47.52 mg/109, 48.32 mg/L, and 6.51, respectively; the sensitivities were 95.4(95%CI: 90.7-98.1), 88.2(95%CI: 81.9-92.8), 87.5(95%CI: 81.2-92.3), and 86.8(95%CI:80.4-91.8), respectively; and the specificities were 95.7(95%CI: 91.9-98.0), 90.8(95%CI: 86.0-94.4), 90.3(95%CI: 85.5-94.0), and 85.0(95%CI:79.4-89.6), respectively. The sensitivities of PCT, CLR, CRP and NLR for predicting bacteremia due to E. coli infection are as high as over 90%, the specificity of PCT is 100, and the sensitivity of NLR is 100. The sensitivity of CRP for predicting bacteremia due to non-Enterobacer infection is 100.

CONCLUSIONS

Compared with those in the control group, PCT, CLR, CRP and NLR were significantly greater in the bacteremia group. The PCT, CLR, CRP, and NLR can all predict the occurrence of bacteremia. The PCT had the highest sensitivity and specificity in predicting bacteremia in ICU patients.

Procalcitonin levels in pregnancy: A systematic review and meta-analysis of observational studies

BACKGROUND

The utility of procalcitonin to identify obstetric sepsis is unknown.

OBJECTIVE

To calculate the mean (range) procalcitonin in pregnancy among healthy women not in labor (group 1), healthy women in labor (group 2), and women with preterm prelabor rupture of membranes (PPROM) without clinical chorioamnionitis (group 3).

SEARCH STRATEGY

NLM PubMed, Elsevier Embase, and Wiley Cochrane Central Register of Controlled Trials from inception to February 21, 2022.

SELECTION CRITERIA

Ten or more pregnant women with procalcitonin reported at more than 20 weeks of pregnancy, with information on labor, PPROM, and infection. Exclusions were major medical comorbidities.

DATA COLLECTION AND ANALYSIS

Each abstract and full-text review was independently reviewed by the same two authors. Quality was reviewed using the Newcastle-Ottawa Scale. A meta-analysis was performed using a random effects model.

MAIN RESULTS

The systematic review included 25 studies: 10 (40%) of good quality and 15 (60%) of poor quality. The meta-analysis included 21 studies. Mean procalcitonin in group 1 was 0.092 ng/mL (range 0.036-0.049 ng/mL), in group 2 it was 0.130 ng/mL (range 0.049-0.259 ng/mL), and in group 3 it was 0.345 ng/mL (range 0.005-1.292 ng/mL).

CONCLUSIONS

Among healthy pregnant women not in labor, procalcitonin levels are comparable to those in non-pregnant adults and may be useful in identifying infection. Procalcitonin levels in other groups overlap abnormal values of procalcitonin in non-pregnant adults, and may not discriminate infection among women in labor or with obstetric comorbidities.

PROSPERO

CRD42020157376, registered 4/28/2020.

Neutrophil CD64 index as a good biomarker for early diagnosis of bacterial infection in pregnant women during the flu season

Background

Pregnant women are at high risk of developing febrile illness during the flu season. Early identification of a viral or bacterial infection is crucial in the management of febrile pregnant patients. Neutrophil CD64 (nCD64) has been shown to have more important diagnostic value in sepsis than traditional inflammatory indicators.

Methods

The pregnant women enrolled were divided into three groups according to disease: influenza A infection, bacterial infection and healthy controls. Peripheral blood CD64, leukocyte, C-reactive protein (CRP), procalcitonin (PCT) and human Th1/Th2-related cytokines levels were routinely measured. The correlation between and diagnostic value of the nCD64 index and other biomarkers were evaluated using Spearman's correlation test and receiver operating characteristic (ROC) curve analysis.

Results

Pregnant women with bacterial infection had significantly elevated levels of leukocytes (8.4 vs. 5.95, 109/L; P = 0.004), CRP (89.70 vs. 50.05 mg/mL; P = 0.031), PCT (0.13 vs. 0.04 ng/mL; P = 0.010) and TNF-α (0.46 vs. 0.38 pg/mL; P = 0.012) and an elevated nCD64 index (12.16 vs. 0.81; P < 0.001) compared with those with influenza A infection. The area under the receiver operating characteristic (AUROC) curve of the nCD64 index to discriminate bacterial infection among pregnant women (AUROC = 0.9183, P < 0.0001) was the largest. The sensitivity and specificity of the nCD64 index at an optimal cut-off value of 3.16 were 84% and 100%, respectively, with a negative predictive value (NPV) of 94%.

Conclusions

Our study demonstrates the clinical value of the nCD64 index in distinguishing between bacterial infection and influenza A in pregnant women.

How should we interpret lactate in labour? A reference study

OBJECTIVE

To investigate maternal lactate concentrations in labour and the puerperium.

DESIGN

Reference study.

SETTING

Tertiary obstetric unit.

POPULATION

1279 pregnant women with good perinatal outcomes at term.

METHODS

Electronic patient records were searched for women who had lactate measured on the day of delivery or in the following 24 hours, but who were subsequently found to have a very low likelihood of sepsis, based on their outcomes.

MAIN OUTCOME MEASURES

The normative distribution of lactate and C-reactive protein (CRP), differences according to the mode of birth, and the proportion of results above the commonly used cut-offs (≥2 and ≥4 mmol/l).

RESULTS

Lactate varied between 0.4-5.4 mmol/l (median 1.8 mmol/l, interquartile range [IQR] 1.3-2.5). It was higher in women who had vaginal deliveries than caesarean sections (median 1.9 vs. 1.6 mmol/l, pdiff  < 0.001), demonstrating the association with labour (particularly active pushing in the second stage). In contrast, CRP was more elevated in women who had caesarean sections (median 71.8 mg/l) than those who had vaginal deliveries (33.4 mg/l, pdiff  < 0.001). In total, 40.8% had a lactate ≥2 mmol/l, but 95.3% were <4 mmol/l.

CONCLUSIONS

Lactate in labour and the puerperium is commonly elevated above the levels expected in healthy pregnant or non-pregnant women. There is a paucity of evidence to support using lactate or CRP to make decisions about antibiotics around the time of delivery but, as lactate is rarely higher than 4 mmol/l, this upper limit may still represent a useful severity marker for the investigation and management of sepsis in labour.

An evaluation into the use of procalcitonin levels as a biomarker of bacterial sepsis to aid the management of intrapartum pyrexia and chorioamnionitis

BACKGROUND

Procalcitonin is an established biomarker for bacterial sepsis in the nonpregnant population with better diagnostic and prognostic value for bacterial infections.

OBJECTIVE

This study aimed to evaluate whether procalcitonin levels could be used in the diagnosis and management of intrapartum sepsis in women and their neonates suspected of intrapartum bacterial sepsis.

STUDY DESIGN

A prospective observational cohort study was conducted at the University Hospitals of Bristol and Weston NHS Foundation Trust. Overall, 117 women and their neonates managed for suspected intrapartum sepsis from June 2020 to October 2020 were included. Procalcitonin levels were measured in addition to routine biomarkers white cell count and C-reactive protein in women and their neonates during the initial septic screen and follow-up blood samples. The placentas underwent detailed histopathology. Maternal and neonatal parameters were used to categorize cases into “high-suspicion bacterial sepsis,” “equivocal bacterial sepsis,” and “low-suspicion bacterial sepsis.” The Kruskal-Wallis test was used to compare categories with biomarker values and placental histology scores.

RESULTS

Procalcitonin level was increased in 6 women in the initial septic screen sample, compared with 100 women with an increased C-reactive protein level. There was a significant difference in maternal postnatal procalcitonin results between “high-suspicion bacterial sepsis” and “low-suspicion bacterial sepsis” categories (P=.004). Moreover, 71.2% of placentas showed varying degrees of chorioamnionitis.

CONCLUSION

In our cohort of women, 94.6% had normal procalcitonin levels while in labor at the time of the septic screen, consistent with the low number of confirmed bacteremia. The result provided a basis that procalcitonin may complement clinical judgment and interpretation of already used prognostic and diagnostic tests, improving patient care in the management of intrapartum sepsis.

Term Neonatal Complications During the Second Localized COVID-19 Lockdown and Prolonged Premature Rupture of Membranes at Home Among Nulliparas With Reference Interval for Maternal C-Reactive Protein: A Retrospective Cohort Study

OBJECTIVE

The COVID-19 lockdown extended premature rupture of membranes (PROM) expectant time among nulliparas and increased the risk of term neonatal complications. This study investigated the impact of term nulliparas with PROM delays at home on neonatal outcomes during the COVID-19 lockdown period, considering the clinical diagnostic application of maternal C-reactive protein (CRP).

METHODS

This study collected 505 term nulliparous women who underwent PROM at home from five provinces in a non-designated hospital of China in 2020. We analyzed PROM maternal information at home and neonatal complications in the COVID-19 regional lockdown and compared related information in the national lockdown. Poisson regression models estimated the correlation of PROM management at home, maternal CRP, and neonatal morbidity. We constructed two diagnostic models: the CRP univariate model, and an assessed cut-off value of CRP in the combined model (CRP with PROM waiting time at home).

RESULTS

In the regional lockdown, PROM latency at home and the severity of neonatal complications were extended and increased lower than in the nationwide lockdown, but term neonatal morbidity was not reduced in the COVID-19 localized lockdown. Prolonged waiting time at home (≥8.17 h) was associated with increasing maternal CRP values and neonatal morbidity (adjusted risk ratio 2.53, 95% CI, 1.43 to 4.50, p for trend <0.001) in the regional lockdown period. In the combined model, CRP ≥7 mg/L with PROM latency ≥8.17 h at home showed higher diagnostic sensitivity and AUC than only CRP for initial assessing the risk of adverse neonatal complications in COVID-19 regional lockdowns (AUC, 0.714 vs. 0.534; sensitivity, 0.631 vs. 0.156).

CONCLUSION

The impact of the acute COVID-19 national blockade on the PROM newborns' health could continue to the COVID-19 easing period. Maternal CRP reference interval (≥7 mg/L) would effectively assess the risk of term neonatal morbidity when nulliparas underwent prolonged PROM expectant at home (≥8.17 h) during the second COVID-19 lockdown.

Clinical findings predictive of maternal adverse outcomes with pyelonephritis

BACKGROUND

Pyelonephritis, a leading cause of infection during pregnancy, is associated with increased maternal adverse outcomes. Therefore, early recognition and intervention of pyelonephritis are important. Early recognition of pyelonephritis has historically been dependent on fever and costovertebral angle tenderness. However, the reliability of these findings to distinguish women who will develop maternal adverse outcomes is limited.

OBJECTIVE

This study aimed to identify clinical variables on presentation that are predictive of maternal adverse outcomes associated with pyelonephritis during pregnancy.

STUDY DESIGN

A retrospective cohort study of pregnant women admitted with pyelonephritis at a single hospital from October 1, 2015, to July 31, 2021, was conducted. The primary outcome was a composite maternal adverse outcome consisting of any of the following: maternal intensive care unit admission, surgical intervention, hypotension requiring vasopressors, acute respiratory distress syndrome, pulmonary edema, mechanical ventilation, high-flow nasal cannula, disseminated intravascular coagulation, altered mental status, dialysis, organ failure, venous thromboembolism, or maternal death. Differences in maternal characteristics and clinical signs and symptoms on admission were stratified by the presence or absence of a maternal adverse outcome. Categorical variables were analyzed using the Fisher exact test. Continuous data were analyzed with Wilcoxon rank-sum test. Sensitivity and specificity and likelihood ratios with 95% confidence intervals were calculated for the detection of maternal adverse outcomes by specified admission physical examination and laboratory findings.

RESULTS

Of 97 women that met the inclusion criteria, 28 (28.9%) had maternal adverse outcomes. Moreover, 50 of 97 women (51.5%) had fever on presentation, with no difference between cohorts recognized. Admission vital signs were not significantly different between cohorts. Costovertebral angle tenderness was present in 78 of 97 women (80.4%) on presentation, with no difference between cohorts. Compared with women without a maternal adverse outcome, women with maternal adverse outcomes were more likely to have leukocytosis (18/28 [64.3%] vs 20/69 [29.0%]), thrombocytosis (3/28 [10.7%] vs 5/69 [7.2%]), bandemia (8/28 [28.6%] vs 7/69 [10.1%]), and an abnormal serum potassium (20/28 [71.4%] vs 32/63 [50.8%]).

CONCLUSION

Admission vital signs may not reliably identify women with pyelonephritis at risk of maternal adverse outcomes. Laboratory studies, particularly a complete blood count and electrolytes, may provide a means of distinguishing those at risk of maternal adverse outcomes.

The effect of gestational age at the time of diagnosis on adverse pregnancy outcomes in women with COVID-19

Objective

We aimed to investigate the incidence of adverse pregnancy outcomes including preterm birth, preeclampsia (PE), and fetal growth restriction (FGR) in pregnant women with COVID‐19 according to the gestational age.

Methods

This retrospective study included 167 pregnant women who were hospitalized with confirmed COVID‐19. The patients were divided into three groups according to the time of diagnosis as follows: <12 weeks of gestation (first trimester, n = 10), 12–24 weeks of gestation (n = 28), and >24 weeks of gestation (n = 129). Medical records of the patients were reviewed retrospectively and adverse pregnancy outcomes were analyzed.

Results

A total of 49 (29.3%) patients had an active COVID‐19 infection at the time of delivery, while 118 (70.7%) gave birth after the infection was cleared. Twenty‐three patients had preterm birth and the gestational age was <34 weeks in only four of these patients. There was no significant difference in the preterm birth, PE, FGR, HELLP syndrome, and gestational diabetes mellitus among the three gestation groups (p = 0.271, 0.394, 0.403, 0.763, and 0.664, respectively). Four (2.39%) patients required intensive care unit stay. Maternal death was seen in only one (0.59%) patient.

Conclusion

Our study showed no significant correlation between the gestational age at the time of COVID‐19 infection and the frequency of adverse pregnancy outcomes such as preterm birth, PE, FGR, and gestational diabetes mellitus. However, further studies are needed to draw a firm conclusion on this topic.

Pregnancy-specific Reference Intervals for BNP and NT-pro BNP-Changes in Natriuretic Peptides Related to Pregnancy

Context

Cardiac disease is the leading cause of maternal mortality in the UK, so accurate cardiovascular diagnoses in pregnancy are essential. BNP (B-type natriuretic peptide) and NT-pro BNP (N-terminal-pro BNP) are useful clinical tools for investigating suspected peripartum cardiomyopathy but, as the pregnancy-specific reference intervals are undefined, it is uncertain how they should be interpreted in pregnant women.

Objectives

To define trimester-specific 95% reference intervals for BNP and NT-pro BNP in pregnancy.

Methods

Longitudinal study of 260 healthy pregnant women, with sampling in each trimester.

Results

The upper reference limit for NT-pro BNP was 200 pg/mL in the first and second trimesters, and 150 pg/mL in the third. Levels were significantly reduced in overweight women in the third trimester (P = .0001), which supports the partitioning of reference intervals by body mass index (BMI). The upper limit for BNP was 50 pg/mL, with no detectable trimester-related differences. Although other biomarkers (hemoglobin and platelets) fell throughout pregnancy, both natriuretic peptides were initially elevated before falling by the third trimester, suggesting that the observed changes in natriuretic peptides are driven by dynamic interplay between cardiac strain and progressive hemodilution. NT-pro BNP in the first trimester was inversely associated with neonatal birthweight at term (P = .011).

Conclusion

Cardiac biomarkers have an important role for investigating suspected disease in high-risk pregnant women, but a robust assessment of the levels expected in healthy pregnant women is an essential prerequisite to their application in clinical practice. This study has defined trimester- and BMI-specific reference intervals for NT-pro BNP and BNP, which may improve how women with suspected cardiovascular disease are investigated in pregnancy.

Reference values for C-reactive protein and procalcitonin at term pregnancy and in the early postnatal period

BACKGROUND

Early recognition of sepsis and prompt treatment improves patient outcome. C-reactive protein is a sensitive marker for tissue damage and inflammation, but procalcitonin has greater specificity for bacterial infection. Limited research exists regarding the use of C-reactive protein and procalcitonin at term pregnancy and the immediate postpartum period.

AIM

This study sought to define reference values for C-reactive protein and procalcitonin at term and the early postnatal period.

METHODS

A prospective cross-sectional study was performed in a university teaching hospital. Venous blood was collected from healthy women (n = 196), aged between 19 and 45 years with an uncomplicated singleton pregnancy, at term (37-40 weeks' gestation) and on day 1 and day 3 postpartum for the measurement of C-reactive protein and procalcitonin.

RESULTS

The reference population comprised of 189 participants: term pregnancy (n = 51), postpartum day 1 vaginal delivery (n = 70) and caesarean section (n = 38) and day 3 (caesarean section, n = 30). The maximum procalcitonin value at term pregnancy was 0.1 μg/L. On day 1 postpartum, 90% and 86.8% of procalcitonin results for vaginal delivery and caesarean section, respectively, were below the decision-threshold of 0.25 μg/L. The specificity of procalcitonin to rule out infection in the reference population was 91.5%.

CONCLUSIONS

Reference values for procalcitonin were established in a well-characterized population of healthy pregnant women at term and immediately postpartum. The variability of C-reactive protein limits its clinical utility in the assessment of systemic sepsis. Application of the procalcitonin cut-off of 0.25 μg/L in this population will be a valuable adjunct to clinicians ruling out infection in pregnancy and postpartum.

Cardiac-specific troponins in uncomplicated pregnancy and pre-eclampsia: A systematic review

Background

The risk of myocardial infarction (MI) increases during pregnancy, particularly in women with pre-eclampsia. MI is diagnosed by measuring high blood levels of cardiac-specific troponin (cTn), although this may be elevated in women with pre-eclampsia without MI, which increases diagnostic uncertainty. It is unclear how much cTn is elevated in uncomplicated and complicated pregnancy, which may affect whether the existing reference intervals can be used in pregnant women. Previous reviews have not investigated high-sensitivity troponin in pregnancy, compared to older, less sensitive methods.

Methods

Electronic searches using the terms “troponin I” or “troponin T”, and “pregnancy”, “pregnancy complications” or “obstetrics”. cTn levels were extracted from studies of women with uncomplicated pregnancies or pre-eclampsia.

Results

The search identified ten studies with 1581 women. Eight studies used contemporary methods that may be too insensitive to use reliably in this clinical setting. Two studies used high-sensitivity assays, with one reporting an elevation in troponin I (TnI) in pre-eclampsia compared to uncomplicated pregnancy, and the other only examining women with pre-eclampsia.

Seven studies compared cTn between women with pre-eclampsia or uncomplicated pregnancy using any assay. Seven studies showed elevated TnI in pre-eclampsia compared to uncomplicated pregnancy or non-pregnant women. One study measured troponin T (TnT) in pregnancy but did not examine pre-eclampsia.

Conclusion

TnI appears to be elevated in pre-eclampsia, irrespective of methodology, which may reflect the role of cardiac stress in this condition. TnI may be similar in healthy pregnant and non-pregnant women, but we found no literature reporting pregnancy-specific reference intervals using high-sensitivity tests. This limits broader application of cTn in pregnancy. There is a need to define reference intervals for cTn in pregnant women, which should involve serial sampling throughout pregnancy, with careful consideration for gestational age and body mass index, which cause dynamic changes in normal maternal physiology.

Pregnancy-specific reference intervals for C-reactive protein improve diagnostic accuracy for infection: A longitudinal study

BACKGROUND AND AIMS

Infections are a major cause of maternal mortality. C-reactive protein (CRP), a commonly-used inflammatory marker, is widely used to inform diagnosis, but the upper limit of normal in pregnancy is uncertain. We have defined trimester-specific reference intervals for CRP and evaluated their diagnostic accuracy for infection.

MATERIALS AND METHODS

Development cohort: longitudinal study of pregnant women to determine 95% reference intervals. Evaluation cohort: diagnostic accuracy study to evaluate these intervals in 50 women with suspected intrauterine infection.

RESULTS

In these 322 healthy pregnant women, CRP was substantially higher than in most non-pregnant populations. CRP was similar in each trimester, with an upper reference limit of 19 mg/L. CRP increased linearly with body mass index (p < 0.0001). The sensitivity and specificity of CRP for diagnosing chorioamnionitis were 73% and 86%, respectively. The overall diagnostic accuracy using the pregnancy-specific reference interval was significantly better than that of the existing standard (p = 0.03).

CONCLUSIONS

CRP is a widely-used clinical tool in pregnancy, and a pregnancy-specific reference interval should be used to optimise diagnostic accuracy. Chorioamnionitis was used as an example of a localised infection with well-defined outcomes, but pregnancy-specific RIs for CRP should be considered in any clinical setting including pregnant women.