Herpes Simplex Virus (HSV) Hepatitis
The cause of this patient's acute liver injury is herpes simplex virus (HSV) hepatitis, indicated by the combination of severe transaminitis (ALT 1880, AST 2170), oral lesions, fever, and second-trimester pregnancy—a clinical pattern that demands immediate acyclovir therapy to prevent maternal mortality.
Clinical Reasoning and Differential Diagnosis
Why HSV Hepatitis is the Answer
The presence of oral lesions in a pregnant patient with markedly elevated transaminases (>1500 U/L) is pathognomonic for disseminated HSV infection. 1 Pregnancy, particularly in the third trimester but also in the second trimester, significantly increases the risk of acute liver failure due to herpes virus, which requires treatment with acyclovir. 1
The key distinguishing features in this case include:
- Oral lesions: This is the critical diagnostic clue that points specifically to HSV rather than other causes of acute hepatitis in pregnancy 1
- Severe transaminitis: ALT 1880 and AST 2170 represent marked hepatocellular injury consistent with viral hepatitis 1
- Second trimester presentation (14 weeks): While HSV hepatitis risk is highest in the third trimester, it can occur earlier in pregnancy 1
- Fever and flu-like symptoms: Consistent with acute viral infection 1
Why NOT the Other Options
HELLP Syndrome (Option A): This diagnosis is excluded by multiple factors. HELLP syndrome is confined to the third trimester or postpartum period, not the second trimester at 14 weeks. 1 The platelet count of 120,000 is only mildly decreased (HELLP requires <100,000). 1, 2 Most importantly, HELLP presents with preeclampsia features (hypertension, proteinuria) in 95% of cases, which are not mentioned here. 2 The transaminase elevation pattern (ALT <500 U/L typically) does not match this case's severe elevation. 1, 2
Hepatitis B Virus (Option C): The serologic profile excludes acute HBV infection. The patient has positive hepatitis B surface antibodies and positive total core antibodies, indicating either past resolved infection or vaccination—not acute infection. 1 Acute HBV would show positive HBsAg, not isolated antibodies. 1
Hepatitis E Virus (Option D): While HEV is a critical consideration in pregnant women with acute hepatitis, particularly in the third trimester where it causes severe outcomes, 1 the presence of oral lesions is not characteristic of HEV infection. 3, 4, 5 HEV typically presents with jaundice, prodromal symptoms, and can cause fulminant hepatic failure in pregnancy, but oral lesions point specifically to HSV. 1, 3, 4 Additionally, HEV is rare in North America (0.4% of acute liver failure cases), 6 and the oral lesions make HSV the definitive diagnosis. 1
Critical Management Implications
Immediate acyclovir therapy is life-saving and must be initiated urgently without waiting for confirmatory testing. 1 The American Association for the Study of Liver Diseases specifically states that pregnancy increases the risk of acute liver failure due to herpes virus, which should be treated with acyclovir. 1
Common Pitfalls to Avoid
- Do not delay acyclovir while awaiting HSV PCR or viral culture results—the presence of oral lesions with severe transaminitis in pregnancy is sufficient to initiate empiric therapy 1
- Do not assume all acute hepatitis in pregnancy is pregnancy-specific liver disease—acute liver failure in pregnant women may be caused by entities not necessarily related to the pregnant state 1
- Do not overlook mucocutaneous lesions—oral or genital lesions are the key diagnostic clue that distinguishes HSV hepatitis from other causes 1
Monitoring and Supportive Care
- ICU-level monitoring is required given the severity of transaminitis and risk of progression to acute liver failure 1
- Serial liver function tests and coagulation studies to assess for hepatic decompensation 1
- Fetal monitoring given the maternal illness severity 1
- Transplant evaluation should be considered if the patient progresses to acute liver failure despite acyclovir therapy 1