Portomesenteric Vein Thrombosis Following Sleeve Gastrectomy: A Case Report and Literature Review

Introduction

The rapid increase in obesity rates has led to a corresponding rise in bariatric surgery cases, bringing with it the challenge of managing related complications. The global complication rate following bariatric surgery is approximately 7%. Portomesenteric venous thrombosis (PMVT) is a rare but potentially life-threatening complication, accounting for 5% to 15% of all mesenteric ischemic events [1].

Although PMVT is uncommon, early recognition and prompt therapeutic anticoagulation often lead to favorable outcomes. However, severe complications, such as intestinal resection, associated with high mortality rates, have been reported. Furthermore, long-term follow-up data for these patients remain limited, particularly regarding the incidence of chronic PMVT, which can result in portal hypertension and necessitate orthotopic liver transplantation.

Recognizing the early signs and symptoms of PMVT is critical, as timely anticoagulation can significantly improve patient outcomes. Managing PMVT requires a multidisciplinary approach involving diagnostic imaging, anticoagulation, and surgical intervention, when necessary. However, the ideal duration of postoperative anticoagulation therapy and the criteria for extended prophylaxis remain subjects of debate. This case highlights the importance of considering PMVT as a potential complication in bariatric surgery, especially in patients at high risk. It underscores the need for vigilance during the postoperative period, to enable timely diagnosis and intervention.

The main objective of this case report and literature review is to describe a novel clinical presentation of portomesenteric thrombosis in a patient following sleeve gastrectomy, to improve the understanding and treatment of this rare complication within bariatric surgery. Additionally, it aims to provide new data on the incidence of PMVT in patients undergoing bariatric surgery, a phenomenon that, although rare, is emerging as a relevant complication in the medical literature. The challenges in diagnosis are discussed, which could influence clinical protocols, particularly in preventing this complication.

Case Report

A 28-year-old woman with grade II obesity (body mass index [BMI] of 39.5 kg/m2, weight 106 kg, height 1.64 m) was scheduled for an elective laparoscopic sleeve gastrectomy. Her personal medical history was unremarkable. She reported no known allergies, had never undergone previous surgery, and denied tobacco use or illicit drug consumption. She consumed alcohol only occasionally. Her chronic medical conditions included polycystic ovary syndrome and metabolic syndrome, both of which were being managed with metformin. She denied any other chronic illnesses, including obstructive sleep apnea. Preoperative evaluation revealed stable vital signs: blood pressure of 128/70 mmHg, heart rate of 86 beats per min, respiratory rate of 16 breaths per min, and oxygen saturation of 98% on room air. Preoperative laboratory tests, performed on January 15, 2024, showed a leukocyte count of 8.2×103/mm3, with 75% segmented neutrophils; erythrocyte count of 4.5×106/mm3; hemoglobin level of 14.3 g/dL; and a platelet count of 433 000/mm3. Coagulation studies were within normal limits, with a prothrombin time of 12.6 s and an activated partial thromboplastin time of 31.1 s. Serologic testing for HIV and syphilis was non-reactive. Her blood type was B positive. An electrocardiogram performed on January 26, 2024, showed normal sinus rhythm, at a heart rate of 90 beats per min, with no signs of ischemia or other abnormalities. A preoperative chest radiograph (posteroanterior view) showed no radiologic pathology. Cardiovascular risk assessment classified the patient with American Society of Anesthesiologists grade II, with a Goldman Index of I, Modified Detsky Index of I, and Obesity Surgery Mortality Risk Score of 0. Overall, she was considered to have moderate thromboembolic risk. The laparoscopic sleeve gastrectomy was performed using standard techniques, without intraoperative complications. The total surgical time was approximately 48 min. Postoperative recovery was uneventful. The patient remained hospitalized for 3 days, during which she had minimal serohematic drainage. A postoperative gastrografin study revealed no evidence of leaks. She was discharged on a liquid diet in stable condition. On postoperative day 7, the patient developed severe gastrointestinal symptoms, including profuse diarrhea and vomiting – more than 10 episodes over a single weekend. She also reported oral intolerance, generalized malaise, and vague abdominal pain that radiated toward the lumbar region. On physical examination, she had dry mucous membranes and a globular abdomen, consistent with her adiposity. Deep palpation elicited tenderness in both the epigastric and mesogastric regions. Her pain level was rated as 4 out of 10 on the visual analog scale. Her surgical wounds were intact, with no signs of infection, and well-approximated skin edges. Given the clinical picture, a gastrointestinal infection was suspected. The patient was admitted for close monitoring and began treatment with intravenous fluids and empiric antibiotic therapy using third-generation cephalosporins. However, after 48 h with no clinical improvement, a contrast-enhanced abdominal and pelvic computed tomography (CT) scan was performed on January 7, 2024. The CT scan revealed multiple findings: intravascular filling defects in the portal vein, superior mesenteric vein, and splenic vein, suggestive of extensive thrombosis (Figures 1–3); thickening of the cecal appendix, possibly due to inflammation; the presence of free intra-abdominal fluid; bilateral basal pulmonary atelectasis; and a small right pleural effusion. Urgent diagnostic laparoscopy was indicated and performed. Intraoperatively, the small bowel loops appeared markedly dilated. Cloudy, free peritoneal fluid was observed, along with necrotic segments of the ileum and a portion of the jejunum (Figure 4). Approximately 2.6 m of small intestine, extending from the ileocecal valve proximally, was resected (Figure 5). A lateral-to-lateral anastomosis was constructed using a laparoscopic linear stapler with white cartridges (Figure 6). The abdominal cavity was irrigated thoroughly, and Jackson-Pratt drains were placed bilaterally in the flanks. The day following surgery, the patient tolerated a liquid diet without difficulty. She was treated with intravenous fluids, non-steroidal anti-inflammatory drugs, a dual antibiotic regimen consisting of a cephalosporin and metronidazole, and therapeutic anticoagulation with enoxaparin. Her clinical condition improved over the following 72 h, with minimal serohematic output from the drains. She was discharged home on postoperative day 5 and instructed to continue oral anticoagulation with rivaroxaban 30 mg once daily for 3 months. In our practice, routine screening for thrombophilia is not typically included in the preoperative workup for bariatric surgery, as it is not part of current standard recommendations. This case illustrates that a patient with no obvious risk factors – beyond undergoing sleeve gastrectomy itself – can still develop a serious and potentially fatal thrombotic complication. According to the literature, laparoscopic sleeve gastrectomy is increasingly recognized as a potential independent risk factor for PMVT, even in patients without underlying hypercoagulable states. Given this experience, it may be worth considering the incorporation of coagulation factor VIII level testing in the preoperative evaluation, as elevated levels have been associated with thrombotic events. At the time of this report, the patient remained asymptomatic. She was tolerating oral intake well, had not had any further episodes of diarrhea or vomiting, and had shown satisfactory postoperative weight loss. She was no longer receiving anticoagulation therapy, which was completed over a 3-month period following hospital discharge.

Discussion

INCIDENCE:

Bariatric surgeries have become increasingly common, with a sharp rise in recent years. The World Obesity Federation estimates that by 2035, a total of 4 billion people worldwide will be affected by overweight and obesity. Portal-splenic-mesenteric vein thrombosis (PSMVT) is a rare but increasingly reported complication following bariatric surgery, particularly after laparoscopic sleeve gastrectomy. Between 5% and 15% of PSMVT cases result in intestinal ischemia [2].

As metabolic surgical procedures become more prevalent, laparoscopic sleeve gastrectomy remains the most commonly performed bariatric procedure, contributing to the rising incidence of rare complications, like PSMVT. Large cohort studies have reported an incidence of PSMVT ranging from 0.3% to 1% following laparoscopic sleeve gastrectomy [3].

ETIOLOGY:

The causes of PSMVT are multifactorial, making it challenging to determine the exact contributors to venous embolism after bariatric surgery. Common risk factors, which also apply to other types of surgery, include prolonged operative time, advanced age, a BMI exceeding 50 kg/m², revision surgeries, major open abdominal surgeries, oral contraceptives, smoking, and, most notably, a history of deep vein thrombosis (DVT), which is a significant risk factor.

Three specific intraoperative factors during gastric sleeve surgery can contribute to PSMVT: dissection too close to the pylorus, dissection and division of the short gastric vessels, and dissection of the posterior gastric wall in proximity to the splenic vein. Over 80% of venous thromboembolism events following bariatric surgery occur within the first 30 days postoperatively, with an average occurrence between 15 and 20 days [4].

Another often-overlooked factor is the lack of routine preoperative laboratory evaluations for abnormalities in the coagulation cascade, or thrombophilias [5]. Elevated factor VIII levels (>150%) are a clinically significant risk factor for venous thrombosis, with levels above 150 IU/dL associated with a 5-fold increased risk [6]. Conditions such as type 2 diabetes mellitus and hyperthyroidism can also contribute to hypercoagulability, leading to DVT through alterations in plasma proteins and coagulation factors [7,8].

The incidence of PSMVT is lower than that of DVT or pulmonary embolism, with rates reported at 0.04%, compared with 0.21% and 0.18%, respectively [9].

PATHOPHYSIOLOGY:

It is important to consider the principles of laparoscopic procedures when using CO2 in the abdominal cavity. The rapid stretching of the peritoneum often triggers a vasovagal response, leading to bradycardia and occasional hypotension. Increased intra-abdominal pressure compresses the inferior vena cava, reducing venous return from the lower extremities. This phenomenon is well documented in patients positioned in the reverse Trendelenburg position for upper abdominal surgeries. Venous engorgement and decreased venous return promote venous thrombosis. The intra-abdominal pressure in patients with obesity is higher than that in individuals with normal weight, which is why those with obesity should be considered at high risk for venous embolism. When CO2 is introduced into the abdominal cavity, as well as into the renal area and other organs, blood flow decreases at the splanchnic level, leading to venous stasis and an increased risk of PSMVT. During bariatric surgery, manipulation of the stomach can cause thermal or mechanical injury to the splenic or mesenteric veins, potentially inducing venous thrombosis. This thrombosis can lead to proximal thrombus propagation, resulting in PSMVT [9]. Other factors related to laparoscopy include sympathetic vasoconstriction induced by hypercapnia and the intraoperative release of vasopressin. It has been suggested that increased intra-abdominal pressure during laparoscopic procedures could reduce splanchnic and portal venous blood flow, potentially promoting venous thrombosis [10].

CLINICAL PRESENTATION:

The symptoms of PMVT secondary to gastric sleeve surgery are often vague and nonspecific, frequently confusing it with other abdominal pathologies. Given the low incidence of this condition, it is essential to consider it in the differential diagnosis and prioritize the most common complications in patients who have undergone sleeve gastrectomy.

The most common symptoms include nausea and vomiting, abdominal pain and distension, and occasionally diarrhea with blood, which could indicate an intestinal infectious process. In more advanced cases, patients can present with signs of peritoneal irritation and fever.

The symptoms described above typically occur when only the mesenteric vein is obstructed. If the thrombus extends to the venous arcades of the mesentery, patients often experience vague lower back pain and signs of ileus, likely due to intestinal infarction. Highly suggestive signs of intestinal infarction include hematochezia, ascites, metabolic acidosis, and multi-organ failure [10].

The most common clinical findings include abdominal pain (82.7%), nausea/vomiting (38.2%), leukocytosis (20%), fever (12.7%), tachycardia (10.9%), elevated liver function tests (11.8%), and increased erythrocyte sedimentation rate and C-reactive protein levels (10%) [11].

DIAGNOSIS:

The most common laboratory abnormalities in patients with PSMVT include elevated liver enzymes, leukocytosis (neutrophilia), mild anemia, and occasionally elevated amylase levels. In more advanced stages, similar to other septic inflammatory processes, signs of coagulopathy and thrombocytopenia can also be present. Although there are no specific laboratory markers for the condition, laboratory test results should be carefully evaluated to raise suspicion of PSMVT following bariatric surgery [12]. Suspicion should primarily arise from clinical evidence of a systemic inflammatory response indicative of an abdominal inflammatory process.

A contrast-enhanced abdominal CT scan is the diagnostic method of choice for SMVT, with a sensitivity of 90% [13]. In a retrospective case series by Dane et al, the most common tomographic findings included thrombi causing partial or total occlusion, with total occlusion being more prevalent. These thrombi can extend to the portal vein. Mesenteric and intestinal edema can result in extensive collateral veins originating from the superior mesenteric vein. Occasionally, initial CT scans reveal thickening of the portal and superior mesenteric vein walls. Follow-up CT scans, performed between 8 and 220 days, can show adjacent collateral circulation to the superior mesenteric vein. Partial recanalization is sometimes observed, with rates of 61% for SMVT and 54% for splenic vein thrombosis after 1 year [14].

MANAGEMENT:

Anticoagulants, such as enoxaparin, have demonstrated excellent results as a preventive measure against venous thromboembolism after surgery. These agents offer higher bioavailability and longer half-lives, as well as a lower risk of causing thrombocytopenia as an adverse effect, than do low-molecular-weight and unfractionated heparins. Patients with obesity, regardless of the degree of obesity, should be considered at high risk for venous thromboembolism. Therefore, it is important to identify all patients who may experience complications following bariatric surgery. According to the literature, the most common presentation of venous thromboembolism occurs within the first 2 weeks following the procedure. It is crucial that all patients with high-risk factors, as determined by venous thromboembolism scales after bariatric surgery, and those with body mass indices greater than 50 kg/m2 (grade IV obesity), receive medical treatment for a minimum of 14 to 30 days. Joint guidelines from the American Association of Clinical Endocrinologists, Obesity Society, and American Society for Metabolic and Bariatric Surgery establish that the dosages of anticoagulants are not specifically detailed; however, they recommend pharmacological thromboprophylaxis after hospital discharge for high-risk groups, such as those with a history of DVT [15]. Direct thrombin inhibitors, such as dabigatran, and factor Xa inhibitors (rivaroxaban, apixaban, and edoxaban) have been developed as effective and safe alternatives to traditional anticoagulant drugs [16]. Preventive medical treatment with activated factor X inhibitors has shown a reduction in the risk of portal mesenteric thrombosis in procedures such as gastric sleeve surgery [17].

In our bariatric medical center, despite our extensive experience, with over 30 000 bariatric procedures, we have encountered only 2 cases of mesenteric ischemia after gastric sleeve surgery. Diagnosing this condition can be challenging, as symptoms can easily be confused with those of other, more common abdominal pathologies. In the early stages, PMVT often presents with nonspecific symptoms, such as abdominal pain, distention, nausea, and fever.

For example, the pathophysiology of PMVT involves a combination of hypercoagulability, venous stasis, and endothelial injury, which can be exacerbated in the postoperative period, due to tissue injury, immobility, and inflammatory response. The interruption of portal venous circulation can lead to intestinal infarction, and chronic complications can result in portal hypertension, cirrhosis, ascites, encephalopathy, and death. This highlights the importance of appropriate follow-up for these patients once their venous thromboembolism issue has been resolved, as many can ultimately require liver transplantation.

Compared with other abdominal procedures, specifically other bariatric surgeries, gastric sleeve surgery appears to confer a higher risk of portal mesenteric thrombosis. Current literature reports an incidence of 0.3% to 1% in patients undergoing gastric sleeve surgery [18]. Thromboembolism following gastric sleeve surgery is multifactorial, and one of the primary factors mentioned in the literature is postoperative readmission, due to complications, as well as surgical duration exceeding 3 h, which has been shown to increase the risk by nearly 57%. Additionally, receiving a transfusion and having a history of prior DVT were identified as the strongest risk factors for developing DVT and pulmonary embolism postoperatively [19]. PMVT after bariatric surgery is a diagnosis that must be considered in the presence of any postoperative abdominal pain; we should not dismiss the possibility of this complication, despite its rarity [20]. DVT can manifest in very different ways, depending on the patient and clinical context. Some studies suggest that progression from the acute to the chronic phase can be influenced by factors such as comorbidity, type of treatment, and the individual’s inflammatory response [21]. The timing of diagnosis and the differentiation between acute and chronic DVT presentations are essential for optimizing clinical care [22]. Early identification of acute DVT makes it possible to initiate anticoagulant therapy promptly, which helps reduce thrombus progression and prevent serious complications [23]. With well-defined diagnostic criteria, more rigorous follow-up can be established. In patients with chronic DVT, periodic imaging allows for evaluation of recanalization and the formation of collateral veins, facilitating intervention in the event of recurrence or complications, such as post-thrombotic syndrome [24]. From a tomographic perspective, acute thrombosis is characterized by the presence of a hypodense filling defect in the affected vein on contrast-enhanced CT, in which the vein often appears distended. Signs of inflammation, such as perivascular edema and mild enhancement of the venous wall, can also be observed. In contrast, chronic thrombosis involves an organized, fibrous thrombus that can partially recanalize and, in some cases, contain internal calcifications. Furthermore, in chronic DVT, the affected vein commonly exhibits a reduced caliber and the development of collateral vessels, as well as irregular thickening of the venous wall. These findings enable differentiation, via CT, between a fresh (acute) thrombus and one that is older and more organized (chronic), which is critical for guiding the appropriate therapeutic strategy [25].

The prevention of venous thromboembolism in bariatric surgery requires a comprehensive approach that combines pharmacological, mechanical, and early mobilization strategies. The use of low-molecular-weight heparin, such as enoxaparin, is essential during the first 14 to 30 postoperative days, especially in patients with a BMI greater than 50 kg/m2 or a history of thrombosis. Additionally, direct oral anticoagulants, such as rivaroxaban, present an effective alternative for prophylaxis. An important factor to consider is the restrictive nature of bariatric procedures, which leads to reduced caloric intake. This can affect the effectiveness of medications that require food to improve their absorption. For example, therapeutic doses of rivaroxaban (15 mg and 20 mg) depend on food to increase absorption: the peak concentration and area under the curve of a 20-mg tablet of rivaroxaban increased by 39% and 76%, respectively, when taken with food. The bioavailability of the 15-mg dose of rivaroxaban reached ≥80% when taken with food. Therefore, the absorption of therapeutic rivaroxaban can be reduced in patients on very restrictive diets, which can limit caloric intake to as low as 500 kcal per day after bariatric surgery. However, the bioavailability of apixaban, dabigatran, edoxaban, and warfarin does not seem to be significantly affected by food intake. The reduced volume for gastric acid secretion leads to a more alkaline pH in the gastric pouch, which could affect pH-dependent drug dissolution and resultant absorption, particularly of drugs that are coated or in controlled-release formulation. Dabigatran, for example, requires an acidic environment for absorption, and while an approximately 20% reduction in absorption was seen when dabigatran was given with antacids, this is thought to not be clinically meaningful [26].

There is controversy regarding which anticoagulant is best, considering that rivaroxaban needs to be taken with food to achieve better bioavailability, unlike dabigatran, apixaban, and edoxaban, which do not require food for absorption. However, dabigatran requires an acidic environment, which can be altered by the 80% gastric resection in sleeve gastrectomy, unlike the other medications.

Studies indicate that, without prophylaxis, the incidence of thromboembolic events can range from 0.5% to 2% in patients at high risk; however, when prophylactic low-molecular-weight heparin is administered, this incidence decreases to less than 1% [27,28]. Nonetheless, using low-molecular-weight heparin at prophylactic doses carries an increased risk of hemorrhagic complications, estimated at around 1% to 2% of cases [29]. For example, in a cohort of 100 patients undergoing bariatric surgery, most thrombotic events could be prevented (reducing them to fewer than 1 case on average), while 1 to 2 patients might experience significant hemorrhagic complications. This favorable balance is achieved through individualized risk stratification, considering factors such as morbid obesity, previous thrombotic events, prolonged immobilization, and other comorbidities, which allows for adjustment of the anticoagulant dose and duration to maximize prevention without unacceptably increasing the risk of bleeding [30].

Combined oral contraceptive medications are the most frequently prescribed medications to young women, with as many as 33% to 40% of women in certain age groups using oral contraceptive at any one time. In addition, approximately 40% of postmenopausal women in the United States have been on hormone replacement therapy.

All studies show a marked increase in the risk of thrombosis within the first months of use of hormonal therapies, with a reported risk for the first 3 months and 9 within the first year. This increased risk within the first year is most pronounced in women aged <30 years. With time, the risk of thrombosis decreases, perhaps because patients with higher risk stop using, due to thrombosis. Estrogen is the most common risk factor for thrombosis in young women. Abundant data have shown that the risk of future thrombosis is low after 3 months of anticoagulation, and therefore, women with any thrombosis on estrogen-only medication can require only short-term anticoagulation for 3 months [31].

Mechanical prophylaxis, using intermittent pneumatic compression devices, should be initiated before surgery and continued postoperatively to enhance blood flow and reduce the risk of thrombosis. Early mobilization, ideally within the first 24 h after surgery, is key to preventing venous stasis and promoting circulation. A thorough preoperative assessment is essential to identify patients at high risk for thromboembolism, such as those with elevated BMI or a history of thrombotic complications, and prophylaxis must be adjusted accordingly. Finally, close postoperative monitoring is crucial to detect early signs of thrombosis, using imaging techniques, such as CT or magnetic resonance imaging if suspected [32,33].

We present the case of a young patient who, despite a delayed diagnosis, had a favorable prognosis. We resolved her case via laparoscopy, as the literature indicates that open abdominal surgery carries a higher risk of thrombosis than does laparoscopic surgery. We believe that a fundamental aspect of her positive outcome was our decision to not perform an open laparotomy; despite extensive intestinal necrosis, we opted to continue with the laparoscopic approach.

The importance of resolving a rare complication, especially by diagnosing it in a timely manner, to slightly improve prognosis, represents a challenge. This is why we always recommend resolving the complication laparoscopically.

Conclusions

Giannopoulos et al in their study focus on practices for venous thromboembolism prophylaxis in patients undergoing bariatric surgery, based on a national survey of directors from Metabolic and Bariatric Surgery Accreditation and Quality Improvement Program-accredited centers. The results show that most centers implement pharmacological prophylaxis with low-molecular-weight heparin or direct oral anticoagulants, but there are significant variations in the duration of treatment and preventive strategies. Some 95% of surgeons administer anticoagulants for at least 10 to 14 days postoperatively, while 50% extend prophylaxis for up to 30 days, depending on individual risk factors. In 85% of centers, graduated compression stockings or intermittent pneumatic compression devices are used in combination with anticoagulants. Only 15% use mechanical compression measures alone without anticoagulants, generally in patients with contraindications to anticoagulation. In 20% of centers, anticoagulants are not administered, due to specific contraindications, such as high risk of bleeding or severe renal insufficiency. In 30% of cases, pharmacological prophylaxis is not used, due to concerns about postoperative bleeding complications [34].

As a result, the incidence of PMVT following this procedure has increased, with an escalating number of reported cases. This rare but serious complication is associated with high mortality rates, with intestinal ischemia occurring in 5% to 15% of cases, and mortality rates ranging from 20% to 50%. While more prevalent in gastric sleeve surgery, PMVT has also been observed in other bariatric procedures, such as Roux-en-Y gastric bypass and laparoscopic adjustable gastric banding.

Despite the wealth of information available regarding preventive measures, there remains ongoing debate about the optimal duration of postoperative anticoagulation therapy.

One of our medical team’s recommendations when caring for these patients is to identify potential risk factors for postoperative venous thrombosis during the preoperative assessment and consultation. Special emphasis should be placed on those with a previous medical history of DVT and a BMI greater than 50 kg/m2, as these are very high risk factors; therefore, we suggest performing coagulation studies to detect thrombophilias. Another important consideration is avoiding dehydration, which is common before bariatric surgery, due to the recommended preoperative diet. Maintaining adequate hydration helps prevent this complication, and we strongly recommend proper fluid intake before surgery. Thromboprophylaxis is essential for patients of reproductive age, particularly for those who have been taking oral contraceptives for less than 3 months, as they are at a higher risk for this complication. We should consider discontinuing it in conjunction with a gynecology consultation and evaluate discharging patients, particularly those with grade IV and V obesity, with anticoagulants for 2 to 4 weeks.

What is clear, however, is the necessity of identifying high-risk patients before bariatric surgery and determining which individuals should be discharged with anticoagulation therapy. At our bariatric medical center, all patients with a BMI greater than 45 kg/m2, as well as those identified as high-risk using a venous thromboembolism scale, are sent home with anticoagulation for 1 month. While some authors advocate for anticoagulation lasting 3 months, others suggest a duration of 6 to 12 months. Nevertheless, the majority of experts, including Rodríguez et al [17], recommend administering rivaroxaban at a daily dose of 10 mg for 1 month, which has proven effective in reducing the risk of PMVT after gastric sleeve surgery.

While gastric sleeve surgery offers substantial benefits for patients with obesity, the rising incidence of portal mesenteric thrombosis underscores the importance of proactive prevention and early detection strategies. A tailored approach to anticoagulation, along with diligent patient monitoring, is essential to improving patient outcomes and minimizing the risk of severe complications.