Swansea Criteria Score in Acute Fatty Liver of Pregnancy
Acute fatty liver of pregnancy (AFLP) is a rare but life-threatening obstetric emergency characterized by microvesicular fatty infiltration of hepatocytes, typically occurring in the third trimester or early postpartum period. This condition poses significant risks to both maternal and fetal health, contributing to high mortality rates if not promptly diagnosed and managed. The Swansea diagnostic criteria, introduced as a clinical tool to standardize AFLP diagnosis, have gained widespread acceptance due to their reliance on clinical and laboratory parameters, circumventing the need for invasive liver biopsies in most cases. This article comprehensively examines the role of the Swansea criteria score in predicting maternal and fetal complications, evaluating disease severity, and guiding therapeutic decisions in AFLP patients.
AFLP incidence varies globally, with estimates ranging from 1 in 7,000 to 1 in 20,000 pregnancies. However, the study conducted at Beijing Ditan Hospital, a specialized liver disease center in China, reported a notably higher prevalence of 1 in 330 pregnancies among 24,054 admissions over a decade. This discrepancy underscores the potential influence of regional referral patterns and institutional expertise on disease detection. Within this cohort, maternal and fetal mortality rates were 4.1% (3/73) and 17.3% (14/81), respectively, aligning with previous reports that emphasize the critical need for early diagnosis and intervention.
The Swansea criteria encompass 14 clinical and laboratory features, requiring the presence of at least six for diagnosis. Key laboratory markers include elevated liver enzymes (alanine aminotransferase [ALT] or aspartate aminotransaminase [AST] >42 U/L), hyperbilirubinemia (>14 mmol/L), coagulopathy (prothrombin time >14 s or activated partial thromboplastin time >34 s), hypoglycemia (11 × 10⁹/L), elevated ammonia (>47 mmol/L), and renal dysfunction (serum creatinine >150 mmol/L). Clinical manifestations such as vomiting, abdominal pain, jaundice, and encephalopathy further contribute to the scoring system.
In this retrospective analysis of 73 AFLP cases, 90.4% (66/73) met ≥6 Swansea criteria, while 9.6% (7/73) were diagnosed despite scoring <6, highlighting the criteria’s high sensitivity but imperfect specificity. The study validated the utility of the Swansea score beyond diagnosis, demonstrating its prognostic value for maternal and fetal outcomes. Receiver operating characteristic (ROC) curve analysis revealed significant associations between higher Swansea scores and major complications. For maternal outcomes, a score ≥8 predicted acute liver failure (AUC 0.726, sensitivity 76.7%, specificity 67.4%), hepatic encephalopathy (AUC 0.773, sensitivity 88.3%, specificity 60.0%), acute renal injury (AUC 0.784, sensitivity 60.5%, specificity 97.1%), and the need for artificial liver support or continuous renal replacement therapy (AUC 0.733–0.805). A lower threshold of ≥7 correlated with maternal coma (AUC 0.774, sensitivity 92.3%, specificity 58.3%).
Fetal complications similarly correlated with escalating Swansea scores. Intrauterine distress and neonatal asphyxia were predicted at a cutoff of ≥7 (AUC 0.694–0.741), while scores ≥9 and ≥10 forecasted neonatal death (AUC 0.787) and intrauterine fetal demise (AUC 0.894), respectively. These findings underscore the Swansea system’s capacity to stratify risk and guide antenatal monitoring.
The study further explored the criteria’s relevance to therapeutic decision-making. Patients scoring ≥8 frequently required advanced interventions, including plasma exchange and renal replacement therapies, reflecting multiorgan dysfunction. Notably, the criteria showed limited predictive value for rarer complications like placental abruption, acute pancreatitis, or postpartum hemorrhage, suggesting areas for refinement.
Pathophysiologically, AFLP is linked to mitochondrial dysfunction in fatty acid oxidation, often associated with fetal homozygous mutations in the long-chain 3-hydroxyacyl-CoA dehydrogenase (LCHAD) enzyme. While not explicitly addressed in this study, the metabolic interplay between maternal and fetal compartments may influence disease severity, potentially explaining variability in Swansea scores among patients.
The Swansea criteria’s emphasis on laboratory parameters proved critical in this cohort. Elevated transaminases (97.3%), hyperbilirubinemia (93.2%), leukocytosis (84.9%), and coagulopathy (82.2%) were the most prevalent features, consistent with hepatic and systemic inflammation. Hypoglycemia, present in 64.4% of cases, reflects impaired hepatic gluconeogenesis, while renal dysfunction (68.5%) signals advancing multiorgan failure.
Comparisons with prior validation studies revealed concordant findings. Wang et al. (2017) similarly identified ≥7 Swansea criteria as predictive of stillbirth and renal replacement needs, though their cohort reported lower maternal mortality (1.3% vs. 4.1% in this study). Discrepancies may stem from differences in healthcare infrastructure or timing of intervention. Knight and Goel’s histological validations further corroborate the criteria’s diagnostic accuracy, with hepatic microvesicular steatosis confirmed in 85–90% of Swansea-positive cases.
Limitations of the Swansea system were also evident. Pregnancy-specific physiological changes—such as gestational thrombocytopenia, hemodilutional anemia, and alkaline phosphatase elevation—may confound interpretation of parameters like leukocytosis or coagulopathy. Additionally, the criteria’s reliance on absolute thresholds (e.g., AST >42 U/L) overlooks longitudinal trends that might earlier signal hepatic injury.
Proposed modifications to enhance the Swansea framework include incorporating dynamic laboratory trends, quantitative measures of hepatic synthetic function (e.g., factor V levels), and biomarkers of mitochondrial dysfunction (e.g., acylcarnitine profiles). Integration with imaging modalities like transient elastography or controlled attenuation parameters (CAP) could further improve diagnostic precision while reducing reliance on invasive biopsies.
In conclusion, this study reinforces the Swansea criteria as a robust tool for AFLP diagnosis, risk stratification, and management guidance. The validated cutoff scores enable clinicians to anticipate complications, optimize resource allocation, and initiate timely interventions—critical factors in mitigating this condition’s high morbidity and mortality. Future iterations of the criteria may benefit from adjunctive biomarkers and imaging techniques to address current limitations, particularly in early or atypical presentations.
doi.org/10.1097/CM9.0000000000001821
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