Use of non-invasive scales for detecting esophageal varices in paediatric patients with portal vein thrombosis. / Utilización de escalas no invasivas en la detección de varices esofágicas en pacientes con trombosis venosa portal.

INTRODUCTION: Portal vein thrombosis (PVT) is the most frequent cause of portal hypertension in paediatric population. Baveno VI Consensus considers endoscopic variceal ligation as the second therapeutic option after meso-Rex bypass (surgical shunt). AIM: Analyse the diagnostic profitability of non-invasive scales in order to predict the risk of oesophageal varices (OV) in children with PVT. MATERIAL AND METHODS: Descriptive retrospective study where every upper gastrointestinal endoscopy (UGE) carried on patients <15 years old with non-cirrhotic PVT were included. There were divided according to the presence of OV and sex, cause, age, previous gastrointestinal bleeding or treatments, results of UGE and scales (Clinical Prediction Rule - CPR), Varices Prediction Rule - VPR), King's Variceal Prediction Score - K-VaPS) and Platelet count/Spleen diameter Ratio - PSR). Qualitative variables were expressed as absolute frequency and percentage, and quantitative variables as median and interquartile range. U Mann-Whitney and Hanley-McNeil tests were used for comparisons. RESULTS: Forty-five UGE were analysed. 80% (n=36) presented OV: median of 3 (2-3) and 33.3% (n=12) required endoscopic variceal ligation. Statistical differences were demonstrated between both groups: CPR (142.39 [132.22-166.53] vs. 122.75 [115.24-133.15]; p=0.003), VPR (9.91 [9.36-11.75] vs. 5.6 [3.34-8.39]; p=0.001), K-VaPS (117.86 [99.66-126.58] vs. 99.64 [94.88-10.18]; p=0.019), PSR (2384.62 [1902.22-3201.63] vs. 1252.5 [579.6-2144.42]; p=0.05), with and area under the curve AUROC>75%, without statistical differences between scales. CONCLUSIONS: In paediatric patients with non-cirrotic PVT non-invasive scales can be used as a tool to predict the presence of OV and raise the indication of UGE.

Splenic volume and splenic vein diameter are independent pre-operative risk factors of portal vein thrombosis after splenectomy: a retrospective cohort study.

BACKGROUND: Portal vein thrombosis (PVT) is a common complication following splenectomy. It affects between 5 and 55% of patients undergoing surgery with no clearly defined pre-operative risk factors. The aim of this study was to determine the pre-operative risk factors of PVT. PATIENTS AND METHOD: Single centre, retrospective study of data compiled for every consecutive patient who underwent splenectomy at Toulouse University Hospital between January 2009 and January 2019. Patients with pre- and post-surgical CT scans have been included. RESULTS: 149 out of 261 patients were enrolled in the study (59% were males, mean age 52 years). The indications for splenectomy were splenic trauma (30.9%), malignant haemopathy (26.8%) and immune thrombocytopenia (8.0%). Twenty-nine cases of PVT (19.5%) were diagnosed based on a post-operative CT scan performed on post-operative day (POD) 5. Univariate analysis identifies three main risk factors associated with post-operative PVT: estimated splenic weight exceeding 500 g with an OR of 8.72 95% CI (3.3-22.9), splenic vein diameter over 10 mm with an OR of 4.92 95% CI (2.1-11.8) and lymphoma with an OR of 7.39 (2.7-20.1). The role of splenic vein diameter with an OR of 3.03 95% CI (1.1-8.6), and splenic weight with an OR of 5.22 (1.8-15.2), as independent risk factors is confirmed by multivariate analysis. A screening test based on a POD 5 CT scan with one or two of these items present could indicate sensitivity of 86.2% and specificity of 86.7%. CONCLUSION: This study suggests that pre-operative CT scan findings could predict post-operative PVT. A CT scan should be performed on POD 5 if a risk factor has been identified prior to surgery.

Unusual spontaneous porto-systemic shunt: The importance of diagnosing non-anatomical porto-systemic shunts to improve portal flow in pediatric living-related liver transplantation. Case report.

Collateral circulation secondary to liver cirrhosis may cause the development of large PSSs that may steal flow from the main portal circulation. It is important to identify these shunts prior to, or during the transplant surgery because they might cause an insufficient portal flow to the implanted graft. There are few reports of "steal flow syndrome" cases in pediatrics, even in biliary atresia patients that may have portal hypoplasia as an associated malformation. We present a 12-month-old female who received an uneventful LDLT from her mother, and the GRWR was 4.8. During the early post-operative period, she became hemodynamically unstable, developed ascites, and altered LFT. The post-operative ultrasound identified reversed portal flow, finding a non-anatomical PSS. A 3D CT scan confirmed the presence of a mesocaval shunt through the territory of the right gonadal vein, draining into the right iliac vein, with no portal inflow into the liver. The patient was re-operated, and the shunt was ligated. An intraoperative Doppler ultrasound showed adequate portal inflow after the procedure; the patient evolved satisfactorily and was discharged home on day number 49. The aim was to report a case of post-operative steal syndrome in a pediatric recipient due to a mesocaval shunt not diagnosed during the pretransplant evaluation.

Decoding pylephlebitis: Tracing the path of infected thrombosis and liver abscesses.

Pylephlebitis, a septic thrombophlebitis of the portal vein, is an uncommon but serious complication following an abdominal site of infection, most frequently diverticulitis or appendicitis. It has a high mortality rate, yet it commonly presents with unspecific abdominal complaints and fever, making diagnosis by clinical and laboratory examinations alone, impossible. This report highlights the extensive computed tomography (CT) findings of pylephlebitis with multiple hepatic abscesses thought to be secondary to diverticulitis, in a patient presenting with septic shock. Radiological characteristics differentiating the liver lesions from malignancy, and showing the ascending pathway of vascular involvement from the inferior mesenteric vein to portal veins is presented, as well as the search for the primary site of infection. Recognizing and understanding the imaging findings in pylephlebitis is crucial for diagnosis and avoiding delay of appropriate treatment for this otherwise often fatal condition.

Case report of atypical undernutrition of hypoproteinemia type.

Albumin and prealbumin serve as vital markers reflecting hepatic synthesis activity and overall body nutrient status. Hypoproteinemia can result from various etiological factors, with reduced blood inflow into the liver due to portal vein thrombosis being one such cause. However, literature addressing this specific association remains limited. This report presents an atypical case of malnutrition involving a patient who experienced prolonged hypoproteinemia attributable to a gradual decline in hepatic blood perfusion caused by progressive portal thrombosis and cavernous transformation of the portal vein (CTPV). The case encompasses an in-depth analysis of the factors contributing to undernutrition, the etiology and diagnosis of hypoproteinemia, and its clinical implications. Vigilance for the presence of hypoproteinemia is essential in the management of patients afflicted by progressive portal vein thrombosis complicated by CTPV. Timely and effective interventions aimed at rectifying hypoproteinemia can significantly enhance clinical outcomes. Moreover, reduced hepatic blood flow should be considered a plausible underlying cause in cases of unexplained hypoproteinemia, warranting thorough evaluation. This case underscores the importance of recognizing the intricate interplay between hepatic vascular pathology and protein homeostasis in clinical practice.

Porto-spleno-mesenteric venous thrombosis after elective splenectomy: a retrospective cohort study.

Background: Elective splenectomy is the main treatment for a wide range of haematological diseases. Porto-spleno-mesenteric venous thrombosis represents one of the most severe complications of this procedure. The aim of this study was to evaluate risk factors associated with development of porto-spleno-mesenteric venous thrombosis after elective splenectomy. Methods: All cases of elective splenectomy carried out from April 1st 2017 to January 31st 2023 were included in this single centre retrospective cohort study. Patients' demographics and perioperative data were analysed and correlated with the incidence of postoperative thrombosis. All patients underwent postoperative doppler ultrasound screening for thrombosis. Analysis was performed using SPSS 28, with p-value < 0.05 considered significant. Results: Twenty-two patients (10 women, 12 men) underwent splenectomy during the study period. Indications were: immune thrombocytopenia (n: 6), myeloproliferative disorder (n: 6), hereditary spherocytosis (n: 4), thalassemia (n: 1), lymphoma (n: 1), leukaemia (n: 1), other malignancies (n: 3). Six patients developed porto-spleno-mesenteric venous thrombosis and only 2 of them were symptomatic. Patients were treated with anticoagulation therapy with complete resolution. Analysis identified three main factors associated with thrombosis: spleen diameter (p = 0.03), myeloproliferative disorder (p = 0.02), intraoperative platelet transfusion (p = 0.002) and intraoperative red blood cells transfusion (p = 0.009). Conclusion: Standardized postoperative screening allows prompt diagnosis and treatment of porto-spleno-mesenteric venous thrombosis even in asymptomatic cases. Patient with splenomegaly and affected by myeloproliferative disorder have a greater risk to develop this complication.

Risk factors for postoperative portal vein thrombosis in patients with hepatitis B liver cancer and its impact on mortality-a retrospective study.

Background: The treatment of portal thrombosis is very difficult, which can seriously affect the prognosis of the patients, and thus, preventing postoperative portal thrombosis in patients with hepatitis B liver cancer is crucial. Identifying the risk factors in these patients is key to preventing postoperative portal vein thrombosis. However, relevant research is currently lacking. The present study was to study the risk factors for postoperative portal vein thrombosis in patients with hepatitis B liver cancer and its impact on mortality. Methods: We retrospectively included 663 patients with hepatitis B liver cancer admitted to the Second Affiliated Hospital of Anhui Medical University and Shenzhen University General Hospital from January 2017 to December 2021. The patients were divided into a portal thrombosis group (n=54) and a control group (n=609) according to whether they had portal thrombosis after surgery. The clinical characteristics including alcoholism, D-dimer, surgery method and tumor diameter of the two groups were compared, and the treatment and mortality of the patients in the portal thrombosis group were analyzed. Results: The incidence of portal vein thrombosis in patients with hepatitis B liver cancer was 8.14% (54/663). The area under the Receiver operator characteristics curve for the diagnostic value of D-dimer for postoperative portal vein thrombosis in patients with hepatitis B liver cancer was 0.716 (95% CI: 0.650-0.781, P=0.000). Alcoholism, D-dimer >8.74 mg/L, open surgery, and a maximum tumor diameter >5 cm were identified as risk factors for portal vein thrombosis after surgery in patients with hepatitis B hepatitis cancer [odds ratio: 2.991 (95% CI: 1.234-7.249), P=0.015; odds ratio: 3.269 (95% CI: 1.683-6.349), P=0.000; odds ratio: 6.726 (95% CI: 3.419-13.232), P=0.000; odds ratio: 2.443 (95% CI: 1.344-4.442), P=0.003]. Patients with Grade I or II grade Yerdel (96.30%) were cured after treatment, while two patients with III grade (3.70%) died after surgery. Conclusions: The incidence of portal vein thrombosis after surgery in patients with hepatitis B liver cancer is high. Intervention against risk factors may be beneficial to improve the prognosis of patients with hepatitis B liver cancer.

Multidetector Computed Tomography (MDCT) Findings of Complications of Acute Cholecystitis. A Pictorial Essay.

Acute cholecystitis stands out as one of the most common surgical pathologies that should always be considered in a right-upper abdominal pain emergency. For this, the importance of a correct diagnosis is well described. However, it has been demonstrated that the simple combination of clinical (pain, Murphy's sign) and laboratory (leukocytosis) parameters alone does not provide for ruling in or ruling out the diagnosis of this condition, unless accompanied by a radiological exam. For a long time, and still today, ultrasonography (US) is by far the first-to-proceed radiologic exam to perform, thanks to its rapidity and very high sensibility and specificity for the diagnosis of simple acute cholecystitis. However, acute cholecystitis can undergo some complications that US struggles to find. In addition to that, studies suggest that multidetector computed tomography (MDCT) is superior in showing complicated forms of cholecystitis in relation to sensibility and specificity and for its capability of reformatting multiplanar (MPR) reconstructions that give a more detailed view of complications. They have shown to be useful for a precise evaluation of vascular complications, the anatomy of the biliary tree, and the extension of inflammation to surrounding structures (i.e., colitis). Therefore, based also on our experience, in patients with atypical presentation, or in cases with high suspicion for a complicated form, a MDCT abdomen scan is performed. In this review, the principal findings are listed and described to create a CT classification of acute complications based on anatomical and topographic criteria.

Cirrhosis and partial portal thrombosis leading to severe variceal bleeding, an unusual presentation of sarcoidosis.

INTRODUCTION: Sarcoidosis is a systemic granulomatous disease, characterized by the formation of non-necrotizing granulomas. Even though granulomas are frequently found in liver biopsy, related symptoms rarely occur. In the current article, a case report is pictured to increase the knowledge on portal hypertension in hepatic sarcoidosis. CLINICAL SITUATION: A 62-year-old female was diagnosed with variceal bleeding for which elastic banding was performed. The patient was admitted to the intensive care unit (ICU) as the bleeding persisted and she evolved in hemorrhagic shock. Liver ultrasound detected nodular hepatomegaly and partial portal thrombosis. Chest CT showed diffuse hilar adenopathies and interstitial micronodular lesion. Finally, PET-CT detected metabolic active liver, bone marrow, and upper and lower diaphragmatic adenopathies. CLINICAL RESOLUTION: Multidisciplinary discussion brought major advantages in rapid diagnosis and prompt effective treatment. Cirrhosis was diagnosed by liver nodularity on imaging and liver biopsy. Sarcoidosis diagnosis was supported by the biopsies of liver and lymph node, which yielded non-caseating granulomas infiltration. Chest CT scan and PET-CT were also consistent with this diagnosis. The complementary analysis excluded differential diagnosis. The patient was treated with high-dose methylprednisolone with notable clinical improvements and discharge from the ICU. CONCLUSION: Hepatic sarcoidosis can present as life-threatening bleeding due to variceal bleeding caused by portal hypertension. Differential diagnosis is broad when hepatic sarcoidosis is suspected. Therefore, a multidisciplinary discussion is warranted. Anatomopathological examination of two potentially involved organs should be considered to make the appropriate diagnosis. Further studies are requested to investigate the pathophysiological mechanism of portal hypertension.

Perihepatic Biloma in a Non-cirrhotic Patient After Transjugular Intrahepatic Portosystemic Shunt (TIPS).

Biloma is an intrahepatic or extrahepatic collection of bile within the abdominal cavity. It can occur spontaneously, or as a result of trauma to the biliary tree. The clinical presentation can be variable and non-specific. Early diagnosis is crucial given the high mortality rate. Diagnostic modalities include abdominal ultrasound, hepatobiliary scintigraphy, computerized tomography (CT), and magnetic resonance imaging (MRI). Treatment options include interventional radiology (IR)-guided drainage, endoscopic drainage, or surgical drainage with a bile leak repair. We report a case of a middle-aged non-cirrhotic patient who presented with abdominal pain and was noted to have extensive portal vein thrombosis. She underwent transjugular intrahepatic portosystemic shunt (TIPS) with thrombectomy and the hospital course was complicated by elevated liver enzymes and found to have intrahepatic biloma requiring IR-guided drainage.

Successful treatment of rectal varices with antegrade transvenous sclerotherapy via the splenorenal shunt from the transjugular approach.

A 74-year-old patient presented with hematochezia and a history of liver cirrhosis with repeated bleeding from esophageal and rectal varices. Endoscopic examination revealed multiple rectal varices with positive red color signs. Ascites, severe portosystemic thrombosis and a splenorenal shunt were diagnosed on a contrast-enhanced dynamic computed tomography examination. From a transjugular approach, we circumvented thrombosed regions by maneuvering double balloon catheters through the shunt and dilated left colic marginal vein. We managed to successfully obliterate the varices.

Acute portal vein thrombosis in mild cholecystitis. A consequence of coronavirus disease 2019 infection?

La infección por el virus SARS-CoV-2 provoca, además de cuadros respiratorios graves, episodios trombóticos en múltiples localizaciones debido a una mala regulación de la respuesta inmune. Presentamos el caso de un paciente con colecistitis incipiente que desarrolló trombosis portal aguda sin ningún otro antecedente salvo haber pasado de forma asintomática una infección por COVID-19. Dado que esta complicación es extremadamente infrecuente en pacientes sin factores predisponentes ni infecciones graves, consideramos que la infección por COVID-19 pudo ser un factor desencadenante de la trombosis portal y debemos de tenerlo en cuenta de cara al manejo y tratamiento de futuros casos similares.Severe acute respiratory syndrome coronavirus 2019 infection causes, in addition to severe respiratory symptoms, thrombotic episodes in multiple locations due to dysregulation of the immune response. We present the case of a patient with incipient cholecystitis who developed acute portal thrombosis with no other antecedents except having passed an asymptomatic coronavirus disease 2019 (COVID-19) infection. Since this complication is extremely rare in patients without predisposing factors or serious infections, we consider that COVID-19 infection could be a triggering factor for portal thrombosis and we must take it into account in the management and treatment of future similar cases.

A case of systemic lupus erythematosus with marked ascites due to idiopathic non-cirrhotic portal hypertension.

A 43-year-old-woman admitted to our department because of abdominal pain, abdominal distension, pain on both inner thighs and blurred vision lasting for 3 months. Pancytopenia and positive anti-double stranded DNA (dsDNA) antibodies were noted 5 years prior to her hospitalisation. On admission, the patient was diagnosed with systemic lupus erythematosus (SLE) with retinal vasculitis, panniculitis, cholecystitis and enteritis. The ultrasound test revealed a large amount of ascites, splenomegaly, a hypoechoic band in the liver, and portal hypertension with mildly elevated hepatic venous wedge pressure (15 mmHg). Liver biopsy showed no evidence of hepatitis, cholangitis or liver cirrhosis, leading to the diagnosis of idiopathic non-cirrhotic portal hypertension (INCPH). Prednisolone (PSL) at a daily dose of 50 mg and intravenous cyclophosphamide pulse therapy (IVCY) were initiated for SLE, while diuretics were administered for transudative ascites associated with INCPH. Although these symptoms temporarily improved, 2 months later, SLE and ascites effusion aggravated again, and portal vein thrombosis was confirmed by computed tomography. After increasing the dose of IVCY and adding an anticoagulant agent, all symptoms improved, allowing a reduction of the PSL dose. In the present case, the exacerbation of INCPH was associated with the exacerbation of SLE and the occurrence of portal thrombosis, suggesting an autoimmune and thrombotic mechanism of INCPH. On the other hand, splenomegaly, oesophageal varices, the hypoechoic band remained unchanged, suggesting the established organised INCPH was refractory to immunosuppressive agents.

Usage of Direct Acting Oral Anticoagulants in Cirrhotic and Non-Cirrhotic Portal Vein Thrombosis: A Systematic Review.

Thrombosis of the portal vein (PVT) is generally seen in the setting of liver cirrhosis and to a lesser extent in the absence of cirrhosis. There is no clear guidance in relation to approaching treatment with anticoagulation in this condition. The professional societies and guidelines recommend treatment with traditional anticoagulation like low-molecular-weight heparin and vitamin-K antagonists in patients presenting with acute portal vein thrombosis. There is no clarity in relation to treatment in the setting of chronic PVT and in patients with cirrhosis. Also, the role of direct-acting oral anticoagulants (DOACs) that are becoming a preferred choice for anticoagulation for various other indications is not clear in the case of PVT. There are a very few studies in the medical literature that have investigated the role of DOACs in patients with PVT in different settings. Thus, we performed a systematic review of the literature to study the use of DOACs in PVT in patients with and without cirrhosis. The results of the available studies show that DOACS appears to be a promising choice for the treatment of patients with PVT. The availability of more data in the future along with better availability of the approved reversal agents for various DOACs is expected to make DOACS a preferred choice for the clinicians to treat patients with PVT.

Thrombosis of the Portal Vein and Superior Mesenteric Vein in a Patient With Subclinical COVID-19 Infection.

More than 122 million cases of COVID-19 infection have been documented, and hundreds of thousands are being added every day. Several co-morbidities are associated with COVID-19, among which hypercoagulability has garnered the attention of many doctors and researchers. Most cases of vascular thrombosis are noted in intensive care unit (ICU) patients with serious disease; among these, many cases of deep venous thrombosis and pulmonary embolism have been noted. A few cases of portal vein thrombosis have also been documented in ICU patients with severe COVID-19. Here, we present a case of a portal vein and superior mesenteric vein thrombosis in a patient with subclinical COVID-19 infection. Through this case report, we intend to increase the research horizon and wish to help diagnose co-morbidities associated with COVID-19 at an earlier stage.

Budd-Chiari syndrome as a complication of eosinophilic granulomatosis with polyangiitis in a young Chinese man: a case report.

Hepatic vein thrombosis is a rare occurrence in the clinical course of eosinophilic granulomatosis with polyangiitis (EGPA). The major mechanism of thrombosis has been postulated to involve the release of toxic proteins from eosinophils. A 36-year-old man with EGPA was admitted to our hospital in July 2018 with hematemesis and melena. Findings on physical examination included ascites and pigmentation of the lower extremities. Ultrasonography of the hepatic vein and inferior vena cava showed an obstruction of the hepatic vein. Magnetic resonance imaging showed low enhancement in the right hepatic vein region. At 34 years of age, the patient's EGPA had initially presented as asthma with eosinophilia (white blood cell count of 11.46 × 1012/L with 14.6% eosinophils). His skin biopsy showed infiltration of inflammatory cells and eosinophils, especially around medium-sized vessels, which was consistent with EGPA. The patient was thus diagnosed with Budd-Chiari syndrome associated with EGPA.

Intrahepatic portal vein thrombosis due to postoperative biliary obstruction successfully treated by a partial thrombectomy combined with thrombolytic drug therapy.

INTRODUCTION: This case report aims to inform pancreatic surgeons about our perioperative management of intrahepatic portal vein thrombosis caused by an obstruction of hepaticojejunostomy (HJ) after pancreaticoduodenectomy (PD). CASE PRESENTATION: A 65-year-old woman was diagnosed with pancreas head carcinoma involving the superior mesenteric vein (SMV). Pancreaticoduodenectomy combined with SMV resection was followed by HJ. Twisting or narrowing was not evident during anastomosis. Total bilirubin values progressively increased to 13mg/dL on day 5. At that time, we suspected anastomotic occlusion and found complete portal thrombosis of the left liver. Therefore, emergency re-anastomosis of the HJ was followed by thrombectomy, which was not completely successful and did not completely recover initial portal flow. Thrombolytic drugs improved obstructive jaundice, eradicated the organized thrombosis and recovered the portal flow by day 30. The post-operative course was uneventful. DISCUSSION: A thrombosis immediately formed in the portal vein due to biliary obstruction of an anastomotic site. We speculated that biliary dilation and related inflammation caused a relative increase in arterial flow and decreased portal flow at the localized part of the umbilical portion. Although early surgical thrombectomy was attempted soon after the primary operation, the organized thrombosis persisted. However, thrombolytic therapy eradicated the thrombosis. CONCLUSION: Careful anastomosis of HJ during PD was necessary to avoid postoperative biliary stricture. This type of complication affects intrahepatic blood flow, particularly via the portal vein. Although immediate re-anastomosis or thrombectomy is applied, organized thrombosis cannot always be surgically removed.

Is Portomesenteric Vein Thrombosis After Laparoscopic Sleeve Gastrectomy Related to Short-Course Prophylaxis of Thromboembolism? A Monocentric Retrospective Analysis About an Infrequent but Not Rare Complication and Review of the Literature.

BACKGROUND: Portomesenteric vein thrombosis (PMVT) is considered a rare and potentially fatal complication of bariatric surgery. Laparoscopic sleeve gastrectomy (LSG) is one of the most performed bariatric procedures in the world. PMVT in LSG was first reported in 2009 by Berthet et al. in a thrombophilic patient. No data exist regarding the real prevalence of this complication specifically after LSG. METHODS: We examined retrospectively all the clinical records of patients who underwent LSG for morbid obesity from January 2011 to December 2016. Moreover, we performed a literature search of PubMed, Medscape, and EMBASE databases, in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. RESULTS: 2854 patients underwent LSG for morbid obesity from January 2011 to December 2016. The retrospective analysis of our records revealed only 1 case of PMVT. The 18 studies selected include 62 cases of PMVT after LSG with a prevalence of 0.52% (ranging from 0.2% to 1.81%) and a mortality rate of 1.61%. CONCLUSIONS: PMVT is an infrequent but not rare complication in patients who undergo LSG. Short-course antithrombotic prophylaxis (<10 days) could increase the risk of this complication. The authors recommend a postoperative prophylaxis with sodium enoxaparin 40 mg sc once a day for 4 weeks. PMVT mortality in patients who undergo LSG is lower than other causes of portal vein thrombosis (hepatic cirrhosis, tumors, myeloproliferative disorders, etc.) If risk factors for PMVT are present preoperatively, the authors recommend a prophylaxis with sodium enoxaparin 40 mg sc twice daily for 4 weeks.