AMERICAN JOURNAL OF PERINATOLOGY/VOLUME 7, NUMBER 4
October 1990
MAGNETIC RESONANCE IMAGING AND COMPUTED TOMOGRAPHY SCAN FOR THE DIAGNOSIS OF ACUTE FATTY LIVER OF PREGNANCY Dan Farine, M.D., Jeffrey Newhouse, M.D., John Owen, M.D., and Harold E. Fox, M.D.
Magnetic resonance imaging (MRI) and computed tomography were used to diagnose fatty liver of pregnancy in a patient with preeclampsia and thrombotic thrombocytopenia purpura. The clinical course included multiple system failure that necessitated mechanical ventilation, dialysis, and plasmapheresis. The MRI picture is described in this entity for the first time. Both imaging techniques are discussed and compared.
Acute fatty liver of pregnancy is a rare but often fatal entity with an incidence of 1:13,328 deliveries1 and a significant maternal morbidity.2 The diagnosis of this entity is made definitively by liver biopsy,3 an invasive procedure that may lead to fatal bleeding in a patient who often has a low platelet count, abnormal liver function tests, and clinically significant bleeding.4 Computed axial tomography (CT) has been recently described to diagnose a case of acute fatty liver of pregnancy.5 Our case has a few unusual clinical features. The diagnosis of acute fatty liver of pregnancy was established using two noninvasive techniques: CT and, for the first time, magnetic resonance imaging (MRI). The clinical course of the patient is summarized and the results of these two diagnostic modalities are described and compared. CASE REPORT
A 29-year-old gravida 2, para 2 patient was transferred to Columbia-Presbyterian Medical Center a few hours postpartum. The transfer diagnosis was severe preeclampsia, liver hematoma, and possible inferior vena cava thrombosis. The patient's past medical history was unremarkable. In her previous pregnancy she had some proteinuria but no hypertension. The previous pregnancy resulted in a term delivery of a female newborn that weighted 2340
gm. The present pregnancy was uneventful until near term, when intrauterine growth retardation was suspected, and the patient was scheduled for induction of labor. On the day of admission for induction, the patient developed, for the first time, signs and symptoms of preeclampsia: epigastric pain, hypertension (blood pressure [BP] 160/100 mmHg) and proteinuria. Labor was induced with oxytocin and was otherwise uneventful. She delivered a 2500 gm male newborn. Postpartum, the patient complained of substernal chest pain and increased abdominal pain. Chest radiograph, arterial blood gases, and a ventilation/per fusion nuclear imaging scan were all within normal limits. CT scan reportedly showed hepatic hematoma and inferior vena cava thrombus. The patient was treated with 8000 U of heparin and 10 hours postpartum was transferred to Columbia-Presbyterian Medical Center. On admission to our center, the patient was complaining of chest pain, right upper quadrant pain, and gingival bleeding. The physical examination revealed a blood pressure of 160/90 mmHg and decreased breath sounds at both lung bases. Laboratory results included hemoglobin, 11.1 gm/dl; hematocrit, 34.7%; white blood cell count, 32,000/mm3; platelets 111,000/mm3, prothrombin time, 15.8/cont. 13.2 sec; partial thromboplastin time, 48.1/cont.31.7 sec; thrombin clotting time 29.2/cont.l5.5 sec; and fibrinogen 200 mg/dl. The patient was treated with
Perinatal Center, Department of Obstetrics and Gynecology, Sloane Hospital for Women; Department of Radiology, Division of Hematology, Department of Medicine, College of Physicians and Surgeons of Columbia University, New York, New York Reprint requests: Dr. Fox, Department of Obstetrics and Gynecology, Columbia-Presbyterian Medical Center, 622 W. 168th St., New York, N.Y 10032
316
Copyright © 1990 by Thieme Medical Publishers, Inc., 381 Park Avenue South, New York, NY 10016. All rights reserved.
Downloaded by: Universite de Sherbrooke. Copyrighted material.
ABSTRACT
magnesium sulfate, oxygen, and 2 U of fresh frozen plasma (FFP). Within 6 hours, her platelets had decreased to 43,000/mm3. The rest of the coagulation profile was unchanged. The patient was given 4 U more of FFP. A venogram of the legs was normal. The CT scan done prior to transfer, in which thrombosis of the inferior vena cava was previously diagnosed, was reviewed. It showed that most of the right lobe of the liver was markedly diminished in density; the borders of the abnormal area were irregular and there was no evidence of displacement or occlusion of the hepatic vessels or of any thrombus (Fig. 1). These findings led to the diagnosis of fatty liver. The heparin treatment was discontinued. The patient continued to have the symptoms already described; although she looked quite sick, there were no additional findings on physical examination. The laboratory results included mild elevation of liver function tests. The electrolytes, renal function tests, ammonia levels, and glucose levels were all within normal limits. The next day the patient complained of blurred vision and was found to have a central scotoma. The coagulation profile had not changed, fibrinogen split products were normal, and there was no active bleeding. The patient developed low-grade fever with no obvious infection. Her liver function tests were grossly abnormal with SGOT, 5060 IU; SGPT, 4410 IU; lactate dehydrogenase, 7140 IU; CPK, 77 IU; total bilirubin, 2.1 mg/dl; albumin, 2.1 gm/dl. The blood film showed changes diagnosic of microangiopathy. Reticulocyte count was 3%. The diagnosis of thrombotic thrombocytopenic purpura (TTP) was made. The patient was placed on prednisone 100 mg and aspirin 300 mg daily and plasma infusion therapy was begun. After cultures were obtained, cefoxitin was initiated. On the second day, the patient developed shortness of breath, with pulmonary edema accompanied by pleural effusions. Her urinary output decreased with an increase in both blood urea nitrogen and creatinine. The patient was transferred to the medical intensive care unit with the following diagnosis: acute fatty liver of pregnancy manifesting as severe
preeclampsia, TTP, renal failure, severe hepatic damage, and pulmonary edema. In the intensive care unit the patient had a stormy course that included respiratory failure and coma. The uremia was treated initially with peritoneal dialysis and later by hemodialysis. Respiratory failure necessitated intubation and ventilation. She underwent daily plasmapheresis with 10 to 12 U of FFP for 12 days. She received a total of 246 U of FFP in her hospital course. Her intensive care stay was 15 days. After her discharge from the intensive care unit, she required chest tube insertion to relieve pleural effusion and the resultant dyspnea. She was discharged 26 days after her admission with a resolution of all the clinical symptoms and laboratory abnormalities. A repeat CT scan performed 6 weeks postpartum showed that the region of diminished density in the posterior hepatic lobe was now considerably smaller in volume than at the previous examination; areas of normal density tissue had appeared within it. An MRI scan was done 2 weeks later (2 months postpartum) (Fig. 2). The T t weighted (TR 700/TE 30) images through the liver revealed an area of mild inhomogeneity in the posterior aspect of the right lobe. The T 2 weighted image (TR2150/TE 50 and 100) also revealed the same picture. The abnormal area in the MRI picture was both smaller and less well defined than in the CT picture. There were no other pathologic conditions detected by either the CT or the MRI scans, and the spleen, pancreas, and kidneys looked normal. Repeat MRI and CT scans that were done 11 months postpartum both showed very mild inhomogeneity in the posterior aspect of the liver.
Figure 1. CT scan at the day of delivery, most of the right lobe of the liver was markedly diminished.
Figure 2. MRI scan 2 months postpartum. The abnormal area is smaller and less defined than in the CT scans. 317
DISCUSSION
This case outlines the catastrophic course that may present as acute fatty liver of pregnancy and preeclampsia. The excellent outcome of this case demonstrates, as previously suggested,1"5 that aggressive management is warranted. An accurate and
Downloaded by: Universite de Sherbrooke. Copyrighted material.
MRI AND CT IN DIAGNOSING FATTY LIVER/Farine, Newhouse, Owen, et al.
AMERICAN JOURNAL OF PERINATOLOGY/VOLUME 7, NUMBER 4
318
tion, when such studies are indicated prior to delivery, is that MRI does not involve ionizing radiation. The persistence of the MRI and CT abnormalities for more than 6 weeks postpartum implies that the diagnosis could be confirmed retrospectively after the acute stage of the disease. Evaluation of fat deposition in liver of women with severe preeclampsia and TTP is necessary not only to improve our understanding of these poorly defined entities, but to enable the institution of early aggressive treatment when fatty liver is diagnosed. Either MRI or CT scan should be considered in the presence of severe preeclampsia with the presence of abnormal liver function tests, especially in the setting of coagulopathy. REFERENCES
1. Pockros PJ, Peters RL, Reynolds TB: Idiopathic fatty liver of pregnancy: Findings in ten cases. Medicine (Baltimore) 63:1-11, 1984 2. Reily CA: Acute fatty liver of pregnancy. Semin Liver Dis 7: 47-54, 1987 3. Fallon HJ: Liver disease. In Burrow GN, Ferris TF (eds.): Medical Complications During Pregnancy. Philadelphia:
WB Saunders, 1982, pp 286 4. Kaplan MM: Acute fatty liver of pregnancy. N Engl J Med 313:367-370, 1985 5. McKee CM, Weir PE, Foster JH, et al: Acute fatty liver of pregnancy and diagnosis by computed tomography. Br MedJ 292:291-292, 1985 6. Bydder GM, Chapman RWG, Harry D et al: Computed tomography attenuation values in fatty liver. J Comput Tomogr 5:33-35, 1981 7. Bova JG, Schenker S: Acute fatty liver of pregnancy. N Engl J Med 313:1608, 1985 8. Bahist B, Hecht HL, Harley WD: Computed tomographic demonstration of rapid changes in fatty infiltration of the liver. Radiology, 142:691-692, 1982 9. Meek DR, Mills PR, Gray HW, et al: A comparison of computed tomography, ultrasound and scintigraphy in the diagnosis of alcoholic liver disease. Br J Radiol 57:23— 27, 1984 10. The Clinical NMR Group: Magnetic resonance imaging of parenchymal liver disease: A comparison with ultrasound, radionuclide scintigraphy and x-ray computed tomography. Clin Radiol 38:495-502, 1987 11. Stark DD, Moss AA, Goldberg HI: Nuclear magnetic resonance of the liver, spleen, and pancreas. Cardiovasc Intervent Radiol 8:329-341, 1986
Downloaded by: Universite de Sherbrooke. Copyrighted material.
early diagnosis of acute fatty liver of pregnancy may decrease maternal and fetal morbidity and mortality. Liver biopsy is the traditional method of diagnosing acute fatty liver of pregnancy, but should not be undertaken when there is a significant risk of bleeding. Therefore noninvasive methods for diagnosis are needed. In the case presented, both CT and MRI scans revealed abnormalities due to focal fatty liver. The CT findings of focal fatty infiltration are specific, as described in a comparative study of liver biopsies in alcoholic fatty livers to CT imaging.6 In this study CT was very accurate in detecting severe fatty infiltration by showing a characteristic reduction in CT numbers. The reduction of CT number is related to the density of the tissue examined. The differential diagnosis of fatty liver includes entities, such as alcohol abuse, diabetes mellitus, and Reye's syndrome that are usually irrelevant to the clinical problem. The detection of fatty liver rules out other relevant diagnostic possibilities, such as preeclampsia without acute fatty liver and viral hepatitis.7 Rapid changes in fatty liver can be followed by CT scan.8 Ultrasound may be used to detect fatty liver, but it is both less specific and less sensitive than CT.9 The normal liver contains 5% of fat, in fatty liver this figure increases to 50%. The CT scan can detect attenuation numbers from 20%; therefore milder forms of fatty liver may not be detected using CT. Bova and Schenker7 speculated that MRI may be the most sensitive method for diagnosing acute fatty liver of pregnancy. In our case the extent of fat deposition detected by the CT scan was larger than that demonstrated on the MRI scan and the CT findings were more striking. However, the MRI scan was performed 2 weeks after the CT scan. The specificity of the MRI findings for fatty changes are quite poor, according to the clinical nuclear magnetic resonance group (detection of 19%) and inferior to CT scanning.10 These studies were confirmed by other groups.11 However, all these studies were performed on alcoholic patients who have triglyceride accumulation, whereas in acute fatty liver of pregnancy there is an accumulation of free fatty acids.4 Therefore these MRI findings may not be applicable to acute fatty liver of pregnancy. Another considera-
October 1990
October 1990
MAGNETIC RESONANCE IMAGING AND COMPUTED TOMOGRAPHY SCAN FOR THE DIAGNOSIS OF ACUTE FATTY LIVER OF PREGNANCY Dan Farine, M.D., Jeffrey Newhouse, M.D., John Owen, M.D., and Harold E. Fox, M.D.
Magnetic resonance imaging (MRI) and computed tomography were used to diagnose fatty liver of pregnancy in a patient with preeclampsia and thrombotic thrombocytopenia purpura. The clinical course included multiple system failure that necessitated mechanical ventilation, dialysis, and plasmapheresis. The MRI picture is described in this entity for the first time. Both imaging techniques are discussed and compared.
Acute fatty liver of pregnancy is a rare but often fatal entity with an incidence of 1:13,328 deliveries1 and a significant maternal morbidity.2 The diagnosis of this entity is made definitively by liver biopsy,3 an invasive procedure that may lead to fatal bleeding in a patient who often has a low platelet count, abnormal liver function tests, and clinically significant bleeding.4 Computed axial tomography (CT) has been recently described to diagnose a case of acute fatty liver of pregnancy.5 Our case has a few unusual clinical features. The diagnosis of acute fatty liver of pregnancy was established using two noninvasive techniques: CT and, for the first time, magnetic resonance imaging (MRI). The clinical course of the patient is summarized and the results of these two diagnostic modalities are described and compared. CASE REPORT
A 29-year-old gravida 2, para 2 patient was transferred to Columbia-Presbyterian Medical Center a few hours postpartum. The transfer diagnosis was severe preeclampsia, liver hematoma, and possible inferior vena cava thrombosis. The patient's past medical history was unremarkable. In her previous pregnancy she had some proteinuria but no hypertension. The previous pregnancy resulted in a term delivery of a female newborn that weighted 2340
gm. The present pregnancy was uneventful until near term, when intrauterine growth retardation was suspected, and the patient was scheduled for induction of labor. On the day of admission for induction, the patient developed, for the first time, signs and symptoms of preeclampsia: epigastric pain, hypertension (blood pressure [BP] 160/100 mmHg) and proteinuria. Labor was induced with oxytocin and was otherwise uneventful. She delivered a 2500 gm male newborn. Postpartum, the patient complained of substernal chest pain and increased abdominal pain. Chest radiograph, arterial blood gases, and a ventilation/per fusion nuclear imaging scan were all within normal limits. CT scan reportedly showed hepatic hematoma and inferior vena cava thrombus. The patient was treated with 8000 U of heparin and 10 hours postpartum was transferred to Columbia-Presbyterian Medical Center. On admission to our center, the patient was complaining of chest pain, right upper quadrant pain, and gingival bleeding. The physical examination revealed a blood pressure of 160/90 mmHg and decreased breath sounds at both lung bases. Laboratory results included hemoglobin, 11.1 gm/dl; hematocrit, 34.7%; white blood cell count, 32,000/mm3; platelets 111,000/mm3, prothrombin time, 15.8/cont. 13.2 sec; partial thromboplastin time, 48.1/cont.31.7 sec; thrombin clotting time 29.2/cont.l5.5 sec; and fibrinogen 200 mg/dl. The patient was treated with
Perinatal Center, Department of Obstetrics and Gynecology, Sloane Hospital for Women; Department of Radiology, Division of Hematology, Department of Medicine, College of Physicians and Surgeons of Columbia University, New York, New York Reprint requests: Dr. Fox, Department of Obstetrics and Gynecology, Columbia-Presbyterian Medical Center, 622 W. 168th St., New York, N.Y 10032
316
Copyright © 1990 by Thieme Medical Publishers, Inc., 381 Park Avenue South, New York, NY 10016. All rights reserved.
Downloaded by: Universite de Sherbrooke. Copyrighted material.
ABSTRACT
magnesium sulfate, oxygen, and 2 U of fresh frozen plasma (FFP). Within 6 hours, her platelets had decreased to 43,000/mm3. The rest of the coagulation profile was unchanged. The patient was given 4 U more of FFP. A venogram of the legs was normal. The CT scan done prior to transfer, in which thrombosis of the inferior vena cava was previously diagnosed, was reviewed. It showed that most of the right lobe of the liver was markedly diminished in density; the borders of the abnormal area were irregular and there was no evidence of displacement or occlusion of the hepatic vessels or of any thrombus (Fig. 1). These findings led to the diagnosis of fatty liver. The heparin treatment was discontinued. The patient continued to have the symptoms already described; although she looked quite sick, there were no additional findings on physical examination. The laboratory results included mild elevation of liver function tests. The electrolytes, renal function tests, ammonia levels, and glucose levels were all within normal limits. The next day the patient complained of blurred vision and was found to have a central scotoma. The coagulation profile had not changed, fibrinogen split products were normal, and there was no active bleeding. The patient developed low-grade fever with no obvious infection. Her liver function tests were grossly abnormal with SGOT, 5060 IU; SGPT, 4410 IU; lactate dehydrogenase, 7140 IU; CPK, 77 IU; total bilirubin, 2.1 mg/dl; albumin, 2.1 gm/dl. The blood film showed changes diagnosic of microangiopathy. Reticulocyte count was 3%. The diagnosis of thrombotic thrombocytopenic purpura (TTP) was made. The patient was placed on prednisone 100 mg and aspirin 300 mg daily and plasma infusion therapy was begun. After cultures were obtained, cefoxitin was initiated. On the second day, the patient developed shortness of breath, with pulmonary edema accompanied by pleural effusions. Her urinary output decreased with an increase in both blood urea nitrogen and creatinine. The patient was transferred to the medical intensive care unit with the following diagnosis: acute fatty liver of pregnancy manifesting as severe
preeclampsia, TTP, renal failure, severe hepatic damage, and pulmonary edema. In the intensive care unit the patient had a stormy course that included respiratory failure and coma. The uremia was treated initially with peritoneal dialysis and later by hemodialysis. Respiratory failure necessitated intubation and ventilation. She underwent daily plasmapheresis with 10 to 12 U of FFP for 12 days. She received a total of 246 U of FFP in her hospital course. Her intensive care stay was 15 days. After her discharge from the intensive care unit, she required chest tube insertion to relieve pleural effusion and the resultant dyspnea. She was discharged 26 days after her admission with a resolution of all the clinical symptoms and laboratory abnormalities. A repeat CT scan performed 6 weeks postpartum showed that the region of diminished density in the posterior hepatic lobe was now considerably smaller in volume than at the previous examination; areas of normal density tissue had appeared within it. An MRI scan was done 2 weeks later (2 months postpartum) (Fig. 2). The T t weighted (TR 700/TE 30) images through the liver revealed an area of mild inhomogeneity in the posterior aspect of the right lobe. The T 2 weighted image (TR2150/TE 50 and 100) also revealed the same picture. The abnormal area in the MRI picture was both smaller and less well defined than in the CT picture. There were no other pathologic conditions detected by either the CT or the MRI scans, and the spleen, pancreas, and kidneys looked normal. Repeat MRI and CT scans that were done 11 months postpartum both showed very mild inhomogeneity in the posterior aspect of the liver.
Figure 1. CT scan at the day of delivery, most of the right lobe of the liver was markedly diminished.
Figure 2. MRI scan 2 months postpartum. The abnormal area is smaller and less defined than in the CT scans. 317
DISCUSSION
This case outlines the catastrophic course that may present as acute fatty liver of pregnancy and preeclampsia. The excellent outcome of this case demonstrates, as previously suggested,1"5 that aggressive management is warranted. An accurate and
Downloaded by: Universite de Sherbrooke. Copyrighted material.
MRI AND CT IN DIAGNOSING FATTY LIVER/Farine, Newhouse, Owen, et al.
AMERICAN JOURNAL OF PERINATOLOGY/VOLUME 7, NUMBER 4
318
tion, when such studies are indicated prior to delivery, is that MRI does not involve ionizing radiation. The persistence of the MRI and CT abnormalities for more than 6 weeks postpartum implies that the diagnosis could be confirmed retrospectively after the acute stage of the disease. Evaluation of fat deposition in liver of women with severe preeclampsia and TTP is necessary not only to improve our understanding of these poorly defined entities, but to enable the institution of early aggressive treatment when fatty liver is diagnosed. Either MRI or CT scan should be considered in the presence of severe preeclampsia with the presence of abnormal liver function tests, especially in the setting of coagulopathy. REFERENCES
1. Pockros PJ, Peters RL, Reynolds TB: Idiopathic fatty liver of pregnancy: Findings in ten cases. Medicine (Baltimore) 63:1-11, 1984 2. Reily CA: Acute fatty liver of pregnancy. Semin Liver Dis 7: 47-54, 1987 3. Fallon HJ: Liver disease. In Burrow GN, Ferris TF (eds.): Medical Complications During Pregnancy. Philadelphia:
WB Saunders, 1982, pp 286 4. Kaplan MM: Acute fatty liver of pregnancy. N Engl J Med 313:367-370, 1985 5. McKee CM, Weir PE, Foster JH, et al: Acute fatty liver of pregnancy and diagnosis by computed tomography. Br MedJ 292:291-292, 1985 6. Bydder GM, Chapman RWG, Harry D et al: Computed tomography attenuation values in fatty liver. J Comput Tomogr 5:33-35, 1981 7. Bova JG, Schenker S: Acute fatty liver of pregnancy. N Engl J Med 313:1608, 1985 8. Bahist B, Hecht HL, Harley WD: Computed tomographic demonstration of rapid changes in fatty infiltration of the liver. Radiology, 142:691-692, 1982 9. Meek DR, Mills PR, Gray HW, et al: A comparison of computed tomography, ultrasound and scintigraphy in the diagnosis of alcoholic liver disease. Br J Radiol 57:23— 27, 1984 10. The Clinical NMR Group: Magnetic resonance imaging of parenchymal liver disease: A comparison with ultrasound, radionuclide scintigraphy and x-ray computed tomography. Clin Radiol 38:495-502, 1987 11. Stark DD, Moss AA, Goldberg HI: Nuclear magnetic resonance of the liver, spleen, and pancreas. Cardiovasc Intervent Radiol 8:329-341, 1986
Downloaded by: Universite de Sherbrooke. Copyrighted material.
early diagnosis of acute fatty liver of pregnancy may decrease maternal and fetal morbidity and mortality. Liver biopsy is the traditional method of diagnosing acute fatty liver of pregnancy, but should not be undertaken when there is a significant risk of bleeding. Therefore noninvasive methods for diagnosis are needed. In the case presented, both CT and MRI scans revealed abnormalities due to focal fatty liver. The CT findings of focal fatty infiltration are specific, as described in a comparative study of liver biopsies in alcoholic fatty livers to CT imaging.6 In this study CT was very accurate in detecting severe fatty infiltration by showing a characteristic reduction in CT numbers. The reduction of CT number is related to the density of the tissue examined. The differential diagnosis of fatty liver includes entities, such as alcohol abuse, diabetes mellitus, and Reye's syndrome that are usually irrelevant to the clinical problem. The detection of fatty liver rules out other relevant diagnostic possibilities, such as preeclampsia without acute fatty liver and viral hepatitis.7 Rapid changes in fatty liver can be followed by CT scan.8 Ultrasound may be used to detect fatty liver, but it is both less specific and less sensitive than CT.9 The normal liver contains 5% of fat, in fatty liver this figure increases to 50%. The CT scan can detect attenuation numbers from 20%; therefore milder forms of fatty liver may not be detected using CT. Bova and Schenker7 speculated that MRI may be the most sensitive method for diagnosing acute fatty liver of pregnancy. In our case the extent of fat deposition detected by the CT scan was larger than that demonstrated on the MRI scan and the CT findings were more striking. However, the MRI scan was performed 2 weeks after the CT scan. The specificity of the MRI findings for fatty changes are quite poor, according to the clinical nuclear magnetic resonance group (detection of 19%) and inferior to CT scanning.10 These studies were confirmed by other groups.11 However, all these studies were performed on alcoholic patients who have triglyceride accumulation, whereas in acute fatty liver of pregnancy there is an accumulation of free fatty acids.4 Therefore these MRI findings may not be applicable to acute fatty liver of pregnancy. Another considera-
October 1990
