Intrahepatic Cholestasis of Pregnancy (ICP) in U.S. Latinas and Chileans: Clinical features, Ancestry Analysis, and Admixture Mapping

Genetic issues in ICP

Intrahepatic cholestasis of pregnancy (ICP) is the commonest gestational liver disorder with variable global incidence. Genetic susceptibility, combined with hormonal and environmental influences, contributes to ICP aetiology. Adverse pregnancy outcomes linked to elevated serum bile acids highlight the importance of comprehensive risk assessment. ABCB4 and ABCB11 gene variants play a significant role in about 20% of severe ICP cases. Several other genes including ATP8B1, NR1H4, ABCC2, TJP2, SERPINA1, GCKR and HNF4A have also been implicated with ICP. Additionally, ABCB4 variants elevate the risk of drug-induced intrahepatic cholestasis, gallstone disease, gallbladder and bile duct carcinoma, liver cirrhosis and abnormal liver function tests. Genetic variations, both rare and common, intricately contribute to ICP susceptibility. Leveraging genetic insights holds promise for personalised management and intervention strategies. Further research is needed to elucidate variant-specific phenotypic expressions and therapeutic implications, advancing precision medicine in ICP management.

Cord blood troponin I levels: biomarker evidence of fetal cardiac injury in intrahepatic cholestasis of pregnancy

BACKGROUND

Intrahepatic cholestasis of pregnancy has been linked to sudden stillbirth. The suddenness of the stillbirths in these cases have led clinicians to suspect that the pathogenesis of stillbirth in women with intrahepatic cholestasis of pregnancy is not related to asphyxia but rather to an undefined etiology. One leading hypothesis relates certain bile acid metabolites to myocardial injury.

OBJECTIVE

The purpose of this study was to determine whether cord blood troponin I levels are increased in fetuses born to mothers with a diagnosis of intrahepatic cholestasis of pregnancy.

STUDY DESIGN

A prospective, case-control study was performed at a single institution between 2017 to 2019 in which 87 pregnant patients with a diagnosis of intrahepatic cholestasis of pregnancy (total bile acids ≥10 μmol/L) were enrolled as cases and 122 randomly selected pregnant patients (asymptomatic with intrapartum total bile acids <10 μmol/L) were enrolled as controls. Cord blood troponin I levels were measured at delivery in both groups using a commercially available chemiluminescent immunoassay. Values ≤0.04 ng/mL were considered negative. Values >0.04 ng/mL were considered positive. The primary outcome was the presence of elevated troponin levels in both cases and controls as a surrogate marker for cardiac status. Our secondary outcomes included neonatal intensive care unit stay, low Apgar scores, neonatal acidosis, and hypoxia indicated by cord blood pH and base excess levels at the time of birth. Chi square and t tests were performed to compare social and obstetrical variables. A P value of <.05 was considered significant. A stratification by total bile acids range of <40 μmol/L, 40 to 100 μmol/L, and >100 μmol/L was performed to assess the relationship between the different severities of intrahepatic cholestasis of pregnancy (by risk of fetal demise with those with total bile acids of >100 μmol/L considered at greatest risk) and the likelihood of a positive troponin I result. Finally, a logistic regression analysis was performed to determine if levels of ≥10 μmol/L were associated with elevated troponin levels.

RESULTS

The mean gestational age at delivery was 38.96±1.47 and 37.71±1.59 weeks of gestation in the controls and cases respectively (P<.001). The mean total bile acids values were 5.2±1.28 ng/mL and 43.2±40.62 ng/mL in the controls and cases respectively (P<.001). Cord blood troponin I was positive in 15 of 122 (12.30%) controls and in 20 of 87 (22.99%) cases. (P<.001). When further stratified by total bile acids levels of <40, 40 to 100, and >100 μmol/L, we found a positive correlation between higher total bile acids levels and a positive troponin I test (P=.002). When controlling for gestational age at delivery, maternal age, and body mass index, higher total bile acids levels were associated with a positive troponin I level (adjusted odds ratio, 1.015; 95% confidence interval, 1.004-1.026).

CONCLUSION

Elevated troponin I was more likely to be found in patients with intrahepatic cholestasis of pregnancy than in those without intrahepatic cholestasis of pregnancy. When stratified by total bile acids levels, a positive troponin I level was more likely to be found with higher levels of total bile acids. In addition, as total bile acids levels increased, they were more likely to be associated with a positive troponin I level. Although there were no stillbirths in our cohort, our findings suggest a potential relationship between cardiac injury and high levels of total bile acids demonstrated by the presence of elevated troponin I levels in cord blood at the time of birth.

GWAS meta-analysis of intrahepatic cholestasis of pregnancy implicates multiple hepatic genes and regulatory elements

Intrahepatic cholestasis of pregnancy (ICP) is a pregnancy-specific liver disorder affecting 0.5-2% of pregnancies. The majority of cases present in the third trimester with pruritus, elevated serum bile acids and abnormal serum liver tests. ICP is associated with an increased risk of adverse outcomes, including spontaneous preterm birth and stillbirth. Whilst rare mutations affecting hepatobiliary transporters contribute to the aetiology of ICP, the role of common genetic variation in ICP has not been systematically characterised to date. Here, we perform genome-wide association studies (GWAS) and meta-analyses for ICP across three studies including 1138 cases and 153,642 controls. Eleven loci achieve genome-wide significance and have been further investigated and fine-mapped using functional genomics approaches. Our results pinpoint common sequence variation in liver-enriched genes and liver-specific cis-regulatory elements as contributing mechanisms to ICP susceptibility.

Navigating Uncertainty: A Case Study of Intrahepatic Cholestasis of Pregnancy

Intrahepatic cholestasis of pregnancy (ICP), the most common liver disorder of pregnancy, is associated with complications for both a pregnant person and their fetus. The underlying cause is not well understood. The pruritus associated with ICP is uncomfortable for pregnant people; however, the primary concern is the fetal risk. Fetal risks include preterm labor and birth and intrauterine fetal demise. This is particularly significant for certain populations because of the disparities in incidence of ICP; in the United States, it disproportionately affects Latinx people, the largest and fastest‐growing minority population. Diagnosis, monitoring, and treatment of ICP are vital to reduce discomfort from pruritis and avoid potential fetal demise. However, diagnosis and treatment are complicated by the lack of definitive diagnostic criteria, the frequent delay in laboratory analysis, and the cost of treatment. This case report aims to improve midwives’ familiarity with ICP and discusses the epidemiology, risk factors, presentation, diagnostic criteria, and available management strategies for this disease as well as the importance of anticipatory guidance regarding increased lifetime risk of ICP in future pregnancies and hepatobiliary disease. Additionally, it discusses the challenges involved in diagnosis and access to treatment. Prompt diagnosis and initiation of treatment may reduce fetal morbidity and mortality.

From Pruritus to Cholestasis: Building a Statistical Model and Online Application to Predict a Diagnosis Prior to Bile Acid Determination

OBJECTIVE

This study aimed to create a statistical model using clinical and laboratory parameters to predict which patients presenting with pruritus in pregnancy will have elevated total bile acids (TBA) and thus, have a high risk of intrahepatic cholestasis of pregnancy (ICP).

STUDY DESIGN

Retrospective cohort study of patients presenting with pruritus in pregnancy and had TBA sent from a single public hospital from January 1, 2017, to December 31, 2017. Primary outcome is TBA ≥ 10 µmol/L. Multivariate logistic regression with stepwise and backward variable selection were used to create predictive models. Four models were compared using Akaike information criterion (AIC), C-statistic, and the DeLong nonparametric approach to test for differences between area under the curve (AUC) of receiver operating characteristic (ROC) curves. Internal validation was performed via fivefold cross-validation technique on the best-fitting, most parsimonious model.

RESULTS

Of the 320 patients with pruritus, 153 (47.8%) had elevated bile acid levels ≥10 µmol/L. Sixty-nine variables were assessed for association with the primary outcome. Five variables were significantly associated with elevated TBA: pruritus of palms and soles (adjusted odds ratio [aOR]: 2.35 [95% confidence interval, CI: 1.22, 4.54]), gestational hypertension (aOR: 0.10 [95% CI: 0.02, 0.60]), log of total bilirubin (aOR: 4.71 [95% CI: 2.28, 9.75]), systolic blood pressure (aOR: 0.97 [95% CI: 0.94, 0.99]), and alanine aminotransferase (aOR: 1.05 [95% CI: 1.02, 1.07]). The final model was chosen for being parsimonious while having the lowest AIC with highest AUC (0.85; 95% CI: 0.81, 0.89). Internal validation using a probability threshold of 50% demonstrated a sensitivity of 65.5%, specificity of 83.5%, and accuracy of 75.1%.

CONCLUSION

We provide a predictive model using five simple variables to determine the probability that a patient presenting with pruritus in pregnancy carries the diagnosis of ICP. This tool, available via a web app, is designed to aid providers and enhance clinical judgment in difficult triage situations.

KEY POINTS

· Currently, no standard method to triage pruritus in pregnancy exists.. · We present a predictive statistical model using five readily available clinical variables.. · Final calculator yields probability of having intrahepatic cholestasis of pregnancy..

Molecular Pathogenesis of Intrahepatic Cholestasis of Pregnancy

Intrahepatic cholestasis of pregnancy (ICP) is a pregnancy-specific liver disease. The maternal symptoms are characterized by skin pruritus and elevated bile acids, causing several adverse outcomes for fetuses, including an increased risk of preterm birth, meconium-stained amniotic fluid, neonatal depression, respiratory distress syndrome, and stillbirth. Genetic, hormonal, immunological, and environmental factors contribute to the pathogenesis of ICP, and the estrogen-bile acid axis is thought to play a dominant role. The advances in the past 10 years uncover more details of this axis. Moreover, dysregulation of extracellular matrix and oxygen supply, organelle dysfunction, and epigenetic changes are also found to cause ICP, illuminating more potential drug targets for interfering with. Here, we summarize the molecular pathogenesis of ICP with an emphasis on the advancement in the past 10 years, aiming to give an updated full view of this field.

Cholestasis: A Prospective Study of Perinatal Outcomes and Time to Symptom Improvement

OBJECTIVE

Although intrahepatic cholestasis of pregnancy (ICP) remains poorly understood, there are several perinatal complications associated with this condition. This study aimed to examine perinatal outcomes of women with ICP, evaluate outcomes according to severity of disease, and monitor time to symptom improvement following diagnosis.

STUDY DESIGN

It involves a prospective, observational study of women with ICP at a single institution. Women with new-onset pruritus without rash were referred to a high-risk obstetrics clinic and evaluated with fasting total bile acids (TBA). Laboratory-confirmed ICP was defined as fasting TBA ≥10 µmol/L. Following diagnosis, a standardized protocol was utilized, including treatment with ursodeoxycholic acid (UDCA). Perinatal outcomes were compared amongst those with and without ICP, and to the general population. Women with ICP were further analyzed based on maximum TBA: 10 to 39, 40 to 99, and ≥100 µmol/L. A Kaplan-Meier survival curve was used to analyze time to symptom improvement.

RESULTS

A total of 404 patients were evaluated and 212 (52%) were diagnosed with ICP. The mean gestational age at diagnosis was 34.1 ± 3.3 weeks. When comparing those with ICP to those not confirmed, and to the general population, there were no differences in age, parity, mode of delivery, preeclampsia, or stillbirth (p > 0.05). Preterm birth was significantly associated with ICP (p < 0.01). This relationship was significant across increasing severity of TBA (p < 0.01) and persisted when examining rates of spontaneous preterm birth (p < 0.01). All women with fasting TBA ≥40 µmol/L delivered preterm due to premature rupture of membranes or spontaneous labor. Time to symptom improvement after diagnosis was over 2 weeks on average; however, this time increased with worsening severity of disease.

CONCLUSION

Despite treatment with UDCA, women with ICP are at increased risk for spontaneous preterm birth, and this risk significantly increased with severity of disease. Although not significant, a trend exists between increasing time to symptom improvement and worsening severity of disease.

KEY POINTS

· Preterm birth is significantly increased in patients diagnosed with intrahepatic cholestasis of pregnancy.. · The risk of preterm birth in women with ICP increases across increasing strata of disease.. · Following initiation of treatment in patients with ICP, symptom improvement takes more than 2 weeks..

Burden of Future Liver Abnormalities in Patients With Intrahepatic Cholestasis of Pregnancy

INTRODUCTION

There are limited data on the incidence, predictors, and time to future liver abnormalities in patients with intrahepatic cholestasis of pregnancy (ICP).

METHODS

Single-center retrospective study of pregnant women with and without ICP who delivered from 2005 to 2009 evaluating incidence and time to future liver abnormalities. Women returning for care with liver function tests at a minimum of 6 months postpartum were included. Liver disease diagnoses and liver functions test abnormalities were compared. Time to development of alanine aminotransferase (ALT) >25 U/L, alkaline phosphatase (ALP) >140 U/L, and diagnosis of liver disease (through imaging or clinical evaluation) were compared between women with and without ICP using Kaplan-Meier methods and Cox regression models.

RESULTS

A total of 255 women with ICP and 131 age-matched control subjects with delivery during the same period were identified. Subjects in both groups were similar in follow-up time, age at pregnancy, prepregnancy body mass index, and ethnicity (≥75% were Hispanic in both groups). On univariate analyses, ICP was associated with increased incidence of ALT >25 U/L P < 0.01 ALP >140 U/L (P < 0.01) and liver disease (P = 0.03). Adjusting for metabolic factors, ICP diagnosis was associated with risk of future liver abnormalities: postpartum ALT >25 U/L (hazard ratio [HR] 1.9, P < 0.01), ALP >140 U/L (HR 3.4, P < 0.01), and liver disease (HR 1.5, P = 0.05).

DISCUSSION

In our cohort of urban women, ICP diagnosis predicted risk of future liver disease and abnormal liver tests. Women with pregnancies complicated by ICP may benefit from surveillance for postpartum liver abnormalities.

Liver disease in pregnancy: Medical aspects and their implications for mother and child

Liver disease during pregnancy is more common than expected and may require specialized intervention. It is important to determine if changes in liver physiology may develop into liver disease, to assure early diagnosis. For adequate surveillance of mother-fetus health outcome, liver disease during pregnancy might require intervention from a hepatologist. Liver diseases have a prevalence of at least 3% of all pregnancies in developed countries, and they are classified into two main categories: related to pregnancy; and those non- related that are present de novo or are preexisting chronic liver diseases. In this review we describe and discuss the main characteristics of those liver diseases associated with pregnancy and only some frequent pre-existing and co-incidental in pregnancy are considered. In addition to the literature review, we compiled the data of liver disease occurring during pregnancies attended at the National Institute of Perinatology in Mexico City in a three-year period. In our tertiary referral women hospital, liver disease was present in 11.24 % of all pregnancies. Associated liver disease was found in 10.8% of all pregnancies, mainly those related to pre-eclampsia (9.9% of pregnancies). Only 0.56% was due to liver disease that was co-incidental or preexisting; the acute or chronic hepatitis C virus was the most frequent in this group (0.12%). When managing pregnancy in referral hospitals in Latin America, it is important to discard liver alterations early for adequate follow up of the disease and to prevent adverse consequences for the mother and child.

Hepatitis B infection and intrahepatic cholestasis of pregnancy: A systematic review and meta-analysis

BACKGROUND

Viral hepatitis type B is caused by hepatitis B virus (HBV) infection. Several studies have linked HBV infection to a higher risk of developing intrahepatic cholestasis of pregnancy (ICP), although some give contradictory results. To investigate the association and estimated risk of ICP in patients with HBV infection, we conducted this meta-analysis to summarize all available evidence.

METHODS

This study consists of 2 meta-analyses. A literature search was performed using MEDLINE and EMBASE from inception to July 2019. The first study included studies that reported associations between HBV infection and the risk of ICP. The second analysis included studies comparing the risk of HBV infection in ICP patients with those without ICP. Odds ratios (OR) and 95% confidence intervals (CI) were calculated using a random-effect, inverse variance method.

RESULTS

Four studies were included in both analyses. The OR of ICP in HBV-infected pregnant women compared with non-HBV pregnant women was 1.68 (95% CI 1.43-1.97; I = 0%). The OR of HBV infection among ICP patients compared with non-ICP patients was 1.70 (95% CI 1.44-2.01; I = 0%).

CONCLUSIONS

Our meta-analysis demonstrates not only a higher risk of ICP among HBV-infected pregnant women but also an increased risk of HBV infection among ICP patients. These findings suggest that HBV is a high-risk factor for ICP and screening for hepatitis B in women with ICP symptoms may be beneficial.

New insights into diagnosis and treatment of intrahepatic cholestasis of pregnancy

Intrahepatic cholestasis of pregnancy (ICP) is a pregnancy-specific disease, characterized by maternal pruritus and abnormal serum biochemistries in the late second and third trimester of pregnancy. The symptoms and abnormal biochemistries resolve rapidly after fetal delivery. As a diagnosis of exclusion, the diagnosis of ICP is based on unexplained pruritus with other causes and impaired liver function presenting with elevated serum liver transaminases and/or bile acids. It is considered as severe ICP when bile acid ≥ 40 μmol/L during pregnancy. The pathogenesis of ICP is still unclear. Adverse perinatal outcomes associated with ICP are focused on increased risk of preterm, meconium-stained amniotic fluid, and perinatal mortality. Unpredictable fetal hypoxia may result in intrauterine fetal death, fetal distress during birth and even stillbirth, and lead to an increase of iatrogenic preterm and cesarean section. The etiology and pathogenesis of fetal stress in ICP are not yet clarified, which may be associated with impaired infrastructure and decreased stress-compensatory in human utero-placental-fetal unit, and related with vascular constriction of chorionic veins and umbilical cord due to elevated bile acids in fetal serum and amniotic fluid. The essential measures of standard treatment of ICP include: (1) monitoring and evaluation of disease, uterine contraction and fetus; (2) prevention and treatment of uterine contraction; (3) treatment with ursodeoxycholic acid (500-1500 mg/d) alone or in combination with S-adenosylmehionine (800-1000 mg/d) or rifampicin (300-1200 mg/d) to promote drainage of bile acids; (4) promotion of fetal growth and lung development; (5) treatment with vitamin K1 before delivery to prevent maternal and fetal hemorrhage; (6) and timely termination of pregnancy. Gestational weeks, fetal condition and severity of disease need to be taken into account when obstetricians decide the time of termination. Elective early delivery is still an effective measure to avoid stillbirth during prolongation of gestational weeks.

Management of intrahepatic cholestasis of pregnancy

Intrahepatic cholestasis of pregnancy (ICP) is the most common liver disease during pregnancy, characterized by otherwise unexplained pruritus in late second and third trimester of pregnancy and elevated bile acids and/or transaminases. ICP is associated with an increased risk of adverse perinatal outcomes for the fetus and the later development of hepatobiliary disease for the mother. Bile acids should be monitored throughout pregnancy since fetal risk is increased at serum bile acids >40 µmol/l. Management of ICP consists of treatment with ursodeoxycholic acid, which reduces pruritus. Early elective delivery is common practice but should be performed on an individualized basis as long as strong evidence supporting this practice is lacking. Mothers should be followed-up for normalization of liver function tests 6-12 weeks after delivery. Future research in large-scale studies is needed to address the impact of ursodeoxycholic acid and early elective delivery on fetal outcome.

Immunology of hepatic diseases during pregnancy

The mother's immune system has to adapt to pregnancy accepting the semi-allograft fetus and preventing harmful effects to the developing child. Aberrations in feto-maternal immune adaptation may result in disease of the mother, such as liver injury. Five pregnancy-associated liver disorders have been described so far, however, little is known concerning immune alterations promoting the respective disease. These liver disorders are pre-eclampsia, hemolysis, elevated liver enzymes, low platelet count (HELLP), acute fatty liver, hyperemesis gravidarum, and intrahepatic cholestasis of pregnancy. On the other hand, pre-existing autoimmune liver injury of the mother can be affected by pregnancy. This review intends to summarize current knowledge linking feto-maternal immunology and liver inflammation with a special emphasis on novel potential biomarkers.

The pathophysiology of intrahepatic cholestasis of pregnancy

A number of liver disorders are specific to pregnancy. Amongst these, intrahepatic cholestasis of pregnancy (ICP), also known as obstetric cholestasis (OC), is the commonest, affecting approximately 1 in 140 UK pregnancies. Patients commonly present in the third trimester with severe pruritus and deranged serum liver tests; bile acids are elevated, in severe cases >40 μmol/L. Although the disease is considered relatively benign for the mother, increased rates of adverse fetal outcomes, including stillbirth, are associated with ICP. As our knowledge of the mechanisms underlying bile acid homeostasis has advanced in the last 15 years our understanding of ICP has grown, in particular with respect to genetic influences on susceptibility to the disease, the role of reproductive hormones and their metabolites and the possible identity of the pruritic agents. In this review, we will describe recent advances in the understanding of this condition with a particular emphasis on how aspects of genetic and reproductive hormone involvement in pathophysiology have been elucidated. We also review recent developments regarding our knowledge of placental and fetal pathophysiology and the long-term health consequences for the mother and child.

Intrahepatic cholestasis of pregnancy: Recent advances

Intrahepatic cholestasis of pregnancy, also known as obstetric cholestasis, is a pruritic condition of pregnancy characterized by an underlying elevation in circulating bile acids and liver derangement, and associated with adverse fetal outcomes, such as preterm labor and stillbirth. Limited understanding of the underlying pathophysiology and mechanisms involved in adverse outcomes has previously restricted treatment options and pregnancy management. Recent advances in these research fields provide tantalizing targets to improve the care of pregnant women affected by this condition.