Abnormal liver function tests (LFTs) occur in 3%-5% of pregnant women. The causes are varied and require proper evaluation and diagnosis. The first step to interpret the changes of LFTs during pregnancy is to distinguish between physiological changes and pathological changes related to liver disease.
Physiological changes in LFTs during pregnancy are usually mild, short-lived, and rarely show persistent abnormalities. In addition, severe liver disease during pregnancy is relatively rare, and pregnancy-related liver disease is the most common cause of abnormal liver function during pregnancy, which seriously threatens the survival of the fetus and mother. For women with liver damage during pregnancy, the differential diagnosis of pregnancy-related or unrelated liver disease is needed quickly. It can be divided into three categories:
(1) Pregnancy-specific liver diseases, such as intrahepatic cholestasis of pregnancy (ICP), HELLP syndrome, and acute fatty liver of pregnancy (AFLP);
(2 ) Liver and gallbladder diseases during pregnancy, such as viral hepatitis, cholelithiasis, etc.;
(3) Pregnancy in patients with previous chronic liver diseases (such as chronic hepatitis, cirrhosis, Budd-Chiari syndrome, etc.).
This article will mainly explain the abnormal LFTs during pregnancy.
Markers of liver cell injury: AST and ALT
Elevated AST or ALT within 1.5 times the upper limit of normal does not necessarily indicate liver disease. If elevated AST or ALT occurs, especially in asymptomatic pregnant women, it is necessary to exclude alcohol use/abuse, acute viral hepatitis, acute toxic injury (such as drug-induced liver injury), and liver ischemic injury. Previous chronic liver diseases, such as non-alcoholic fatty liver disease (NAFLD), viral or autoimmune hepatitis, etc., may be combined with pregnancy and cause abnormal liver function. If all of these possibilities are ruled out, it is necessary to consider liver damage specific to pregnancy (Figure 1).
Figure 1 Transaminase abnormalities caused by liver injury during pregnancy
Especially in early pregnancy, the main cause of elevated transaminase is hyperemesis gravidarum, with an incidence of 0.3%-2% , Which is characterized by nausea and vomiting. Transaminase can be raised to 20 times the upper limit of normal, rarely accompanied by jaundice. After the vomiting symptoms subsided, the LFTs returned to normal.
In the second and third trimester of pregnancy, hypertransaminaseemia is associated with preeclampsia/eclampsia, HELLP syndrome, AFLP, and ICP, although ICP is usually characterized by cholestatic damage.
Cholestasis
Many pregnant women have symptoms of cholestasis. In the case of cholestasis, three basic concepts need to be considered:
(1) Pregnant women who have symptoms of cholestasis at any stage of pregnancy should be examined, including family medical history and medication history, complete physical examination and Serological evaluation;
(2) The examination must consider pregnancy-specific liver disease and non-pregnancy-related cholestatic diseases (pre-pregnancy);
(3) Even if the focus is on cholestasis-related indicators (ALP) And GGT), but almost all cases showed a slight increase in transaminases.
The key to cholestasis examination is abdominal ultrasound, which is safe and is also the preferred imaging method during pregnancy. Abdominal ultrasound can distinguish extrahepatic cholestasis from intrahepatic cholestasis, as well as common cholestasis diseases observed during pregnancy.
If the ultrasound is undiagnosed and further imaging is required, MRI imaging can be used in the second and third trimester of pregnancy. However, it is not recommended to use gadolinium enhancers, which will pass through the placenta and be excreted into the amniotic fluid by the fetal kidneys. They will exist for a long time in the amniotic fluid and cause potential damage to the fetal lungs and gastrointestinal system.
Yimaitong compiled and compiled from: Guarino M, Cossiga V, Morisco F. The interpretation of liver function tests in pregnancy. Best Pract Res Clin Gastroenterol. 2020;44-45:101667. doi:10.1016/j.bpg.2020.101667
