Splenic Hematoma

Splenic hematoma is a localized, encapsulated collection of blood within the splenic parenchyma or subcapsular space, resulting from hemorrhage secondary to trauma, neoplasia, or vascular disruption. In veterinary surgery, it is most commonly encountered as a benign, non-neoplastic mass lesion of the spleen, often associated with hematoma formation within a splenic hemangiosarcoma or as a primary benign hematoma. The spleen, a highly vascular organ with a rich sinusoidal network, is particularly susceptible to hematoma formation due to its role in hematopoiesis, immune surveillance, and blood filtration. Splenic hematomas can be classified as acute or chronic, and their clinical significance ranges from incidental findings to life-threatening intra-abdominal hemorrhage. Surgical management typically involves splenectomy, either as a curative procedure for benign hematomas or as a palliative or diagnostic intervention for malignant lesions. The condition is a common indication for emergency abdominal surgery in dogs, particularly in older large-breed dogs, and requires a thorough diagnostic workup to differentiate benign from malignant etiologies.

The etiology of splenic hematoma can be broadly categorized into traumatic, neoplastic, and idiopathic causes. Traumatic splenic hematomas result from blunt abdominal trauma, such as vehicular accidents, falls, or kicks, which cause splenic parenchymal laceration and hemorrhage. In such cases, the hematoma forms as a result of direct mechanical injury to the splenic capsule and parenchyma. Neoplastic causes are the most common in veterinary patients, with hemangiosarcoma being the primary malignant neoplasm associated with splenic hematoma formation. Hemangiosarcoma is a highly aggressive endothelial cell tumor that forms irregular, blood-filled cavities and is prone to spontaneous rupture, leading to hematoma formation. Other neoplastic causes include lymphosarcoma, mast cell tumor, and metastatic lesions, though these are less frequently associated with hematoma formation. Idiopathic or spontaneous splenic hematomas occur without an identifiable cause and are often attributed to underlying vascular fragility, coagulopathies, or hypertension. In some cases, splenic hematomas may develop secondary to splenic torsion, where the splenic pedicle twists, causing venous congestion and subsequent hemorrhage. Additionally, iatrogenic causes, such as splenic biopsy or trauma during abdominal surgery, can lead to hematoma formation. The anatomical vulnerability of the spleen, with its thin capsule and extensive sinusoidal network, predisposes it to hemorrhage and hematoma formation under various pathological conditions.

Splenic hematoma is predominantly a disease of dogs, with a higher incidence in large and giant breeds, including German Shepherds, Golden Retrievers, Labrador Retrievers, and Boxers. These breeds are also predisposed to splenic hemangiosarcoma, which is a common underlying cause of splenic hematoma. The condition is rare in cats, and when present, it is often associated with trauma or lymphoma. The age of onset is typically middle-aged to older animals, with a mean age of 8 to 10 years in dogs. There is no significant sex predilection, although some studies suggest a slight male predominance. Working dogs and those with high levels of physical activity may be at increased risk for traumatic splenic hematoma. The incidence of splenic hematoma in dogs is estimated to be 0.3% to 1.5% of all canine neoplasms, with hemangiosarcoma accounting for up to 50% of splenic masses. Benign splenic hematomas are less common than malignant lesions, but they still represent a significant proportion of splenic masses. Breed-specific genetic factors, such as mutations in the TP53 gene, have been implicated in the development of hemangiosarcoma, which may predispose certain breeds to splenic hematoma formation. Overall, the epidemiology of splenic hematoma is closely linked to the prevalence of splenic neoplasia and trauma in the canine population.

The pathophysiology of splenic hematoma involves a cascade of vascular, cellular, and structural events that lead to the accumulation of blood within the splenic parenchyma or subcapsular space. In traumatic cases, direct mechanical injury to the spleen causes rupture of the splenic capsule and laceration of the parenchyma, resulting in hemorrhage. The bleeding may be contained by the splenic capsule, forming a subcapsular hematoma, or may extend into the parenchyma, creating an intraparenchymal hematoma. In neoplastic cases, particularly hemangiosarcoma, the tumor cells proliferate and form irregular, blood-filled vascular channels that are fragile and prone to rupture. As the tumor grows, it outgrows its blood supply, leading to necrosis and hemorrhage within the tumor, which can coalesce to form a hematoma. The hematoma may expand rapidly, causing stretching of the splenic capsule and pain. If the capsule ruptures, free blood enters the peritoneal cavity, leading to hemoperitoneum, hypovolemic shock, and potentially death. The systemic inflammatory response to hemorrhage and tissue necrosis can lead to activation of the coagulation cascade, consumption of clotting factors, and disseminated intravascular coagulation (DIC). Chronic hematomas may undergo organization, with the formation of fibrous tissue and mineralization. The presence of a splenic hematoma can also cause splenomegaly, which may lead to compression of adjacent organs, such as the stomach, causing gastrointestinal signs. Additionally, the hematoma may serve as a nidus for infection, leading to abscess formation. The biomechanical disruption of the splenic architecture impairs the organ's hematopoietic and immune functions, contributing to systemic morbidity.

Predisposing factors for splenic hematoma can be intrinsic or extrinsic. Intrinsic factors include age, breed, and genetic predisposition. Older dogs, particularly those over 8 years of age, are at higher risk due to the increased incidence of splenic neoplasia. Large and giant breeds, such as German Shepherds, Golden Retrievers, and Labrador Retrievers, have a genetic predisposition to hemangiosarcoma, which is a common cause of splenic hematoma. Additionally, dogs with coagulopathies, such as von Willebrand disease or hemophilia, are at increased risk for spontaneous hemorrhage and hematoma formation. Hypertension, either primary or secondary to renal disease or hyperadrenocorticism, can weaken splenic vasculature and predispose to hematoma formation. Extrinsic factors include trauma, such as vehicular accidents or blunt abdominal trauma, which can directly injure the spleen. Iatrogenic factors, such as splenic biopsy or abdominal surgery, can also lead to hematoma formation. Nutritional factors, such as diets high in fat, have been suggested to increase the risk of splenic torsion, which can lead to hematoma. Management factors, such as intense physical activity or participation in high-impact sports, may increase the risk of traumatic splenic injury. Prior splenic surgery or a history of splenic masses may also predispose to recurrence. Overall, the interplay of genetic, conformational, and environmental factors contributes to the development of splenic hematoma.

Clinical signs of splenic hematoma vary depending on the size, location, and whether the hematoma has ruptured. In cases of small, non-ruptured hematomas, animals may be asymptomatic, and the hematoma is often an incidental finding during abdominal imaging or surgery. When clinical signs are present, they are often nonspecific and include lethargy, weakness, anorexia, and weight loss. Abdominal distension may be noted if the hematoma is large or if there is concurrent hemoperitoneum. Palpation of the abdomen may reveal a cranial abdominal mass, splenomegaly, or pain on palpation. In cases of acute rupture, animals may present with acute collapse, pale mucous membranes, tachycardia, weak pulses, and signs of hypovolemic shock. Abdominal distension due to hemoperitoneum may be evident, and abdominal fluid wave may be detected on palpation. Gastrointestinal signs, such as vomiting and diarrhea, may occur due to compression of the stomach or intestines. In some cases, animals may have a history of intermittent episodes of weakness or collapse, which may be due to chronic blood loss and anemia. Neurological signs, such as seizures or ataxia, may occur if the hematoma is associated with a metastatic neoplasm. The severity of clinical signs is directly related to the degree of hemorrhage and the presence of underlying neoplasia. A thorough physical examination, including assessment of mucous membrane color, capillary refill time, and abdominal palpation, is essential for identifying animals with splenic hematoma.

The differential diagnoses for splenic hematoma include a wide range of splenic and abdominal conditions. Key differentials include: 1) Splenic hemangiosarcoma: This malignant neoplasm is the most important differential, as it can present with similar clinical signs and imaging findings. Hemangiosarcoma is characterized by irregular, infiltrative masses with areas of necrosis and hemorrhage. Definitive diagnosis requires histopathology, and the presence of metastasis to the liver, lungs, or other organs is common. 2) Splenic lymphosarcoma: This neoplastic condition can cause diffuse splenomegaly or nodular masses. It is often associated with generalized lymphadenopathy and systemic signs. Cytology or histopathology is needed for diagnosis. 3) Splenic abscess: A bacterial infection of the spleen can lead to abscess formation, which may mimic a hematoma on imaging. Clinical signs include fever, abdominal pain, and leukocytosis. 4) Splenic torsion: Torsion of the splenic pedicle causes venous congestion and splenomegaly, which can lead to hemorrhage and hematoma formation. It is more common in large-breed dogs and is often associated with gastric dilatation-volvulus. 5) Splenic infarction: Ischemia and necrosis of splenic tissue can occur due to thromboembolism or vascular compromise, leading to a focal lesion that may resemble a hematoma. 6) Nodular hyperplasia: Benign hyperplasia of the splenic parenchyma can form nodules that may be mistaken for hematomas. These are usually incidental findings and do not cause clinical signs. 7) Primary splenic sarcoma: Other sarcomas, such as fibrosarcoma or leiomyosarcoma, can occur in the spleen and may present as masses. 8) Metastatic neoplasia: Metastatic tumors from other primary sites can involve the spleen and form masses. 9) Extramedullary hematopoiesis: This benign condition can cause splenomegaly and nodular lesions, often in response to chronic anemia or inflammation. 10) Granulomatous disease: Fungal or mycobacterial infections can cause granulomatous lesions in the spleen, which may mimic hematomas. Differentiation between these conditions requires a combination of imaging, cytology, histopathology, and clinical findings.

The diagnostic algorithm for splenic hematoma begins with a thorough history and physical examination, with particular attention to abdominal palpation and assessment of cardiovascular status. If a splenic mass or hemoperitoneum is suspected, the following steps are recommended: 1) Complete blood count (CBC) and serum biochemistry profile to assess for anemia, leukocytosis, thrombocytopenia, and organ dysfunction. 2) Coagulation profile (PT, aPTT, platelet count, and possibly TEG) to evaluate for coagulopathies and DIC. 3) Abdominal radiography: May reveal a soft tissue mass in the cranial abdomen, splenomegaly, or loss of abdominal detail due to peritoneal fluid. 4) Abdominal ultrasonography: This is the imaging modality of choice for evaluating splenic masses. It can identify the presence of a mass, its echotexture, and the presence of peritoneal fluid. Ultrasound-guided fine-needle aspiration of the mass or fluid can be performed for cytology. 5) Thoracic radiography: To evaluate for pulmonary metastasis, especially if neoplasia is suspected. 6) Advanced imaging: Computed tomography (CT) or magnetic resonance imaging (MRI) may be used for surgical planning and to assess for metastasis. 7) Abdominocentesis or diagnostic peritoneal lavage: If hemoperitoneum is present, fluid analysis can confirm hemorrhage and rule out septic peritonitis. 8) Exploratory laparotomy: If a splenic mass is identified, surgical exploration is often indicated for definitive diagnosis and treatment. Intraoperative biopsy or splenectomy is performed, and histopathology is obtained. 9) Histopathology: The gold standard for diagnosis, which differentiates benign hematoma from malignant neoplasia. The diagnostic algorithm should be tailored to the stability of the patient; unstable patients may require immediate surgery without extensive preoperative imaging.

Laboratory findings in splenic hematoma are variable and depend on the severity of hemorrhage and the underlying cause. A complete blood count may reveal anemia, which can be acute and severe in cases of rupture, or chronic and mild in cases of slow bleeding. The anemia is typically non-regenerative initially, but may become regenerative if the animal survives the acute episode. Thrombocytopenia may be present due to consumption or destruction of platelets, particularly in cases of hemangiosarcoma or DIC. Leukocytosis may be seen in cases of inflammation or infection. A serum biochemistry profile may show elevations in liver enzymes (ALT, AST) due to hepatic hypoxia or metastasis, and elevations in blood urea nitrogen (BUN) and creatinine may indicate prerenal azotemia secondary to hypovolemia. Total protein and albumin may be decreased due to blood loss. Coagulation abnormalities, such as prolonged PT and aPTT, decreased fibrinogen, and elevated D-dimer, may indicate DIC. A urinalysis may reveal hematuria or proteinuria. Blood gas analysis may show metabolic acidosis due to hypoperfusion. Inflammatory biomarkers, such as C-reactive protein (CRP) and serum amyloid A (SAA), may be elevated. Synovial fluid analysis is not typically performed for splenic hematoma, but if joint effusion is present, it may be due to systemic inflammation. Overall, laboratory findings are nonspecific but are essential for assessing the patient's overall health and surgical risk.

Imaging plays a crucial role in the diagnosis and management of splenic hematoma. Abdominal radiography may show a soft tissue mass in the cranial abdomen, splenomegaly, or a loss of serosal detail due to peritoneal fluid. However, radiography is insensitive for detecting small hematomas. Abdominal ultrasonography is the primary imaging modality for evaluating splenic masses. It can identify the presence of a mass, its size, echotexture, and the presence of cavitation or necrosis. Splenic hematomas typically appear as hypoechoic or mixed echogenic masses, sometimes with anechoic areas representing fluid. Ultrasonography can also detect free peritoneal fluid, which may be anechoic (hemorrhage) or echogenic (exudate). Ultrasound-guided fine-needle aspiration of the mass or fluid can be performed for cytology. Computed tomography (CT) provides more detailed anatomical information and is excellent for surgical planning. CT can accurately assess the size and extent of the mass, the presence of metastasis, and the vascular supply. CT angiography can be used to evaluate the splenic vasculature and identify active hemorrhage. Magnetic resonance imaging (MRI) is less commonly used but can provide excellent soft tissue contrast. Thoracic radiography is essential to rule out pulmonary metastasis. In cases of hemoperitoneum, abdominocentesis or diagnostic peritoneal lavage can be performed to confirm hemorrhage. Advanced imaging, such as CT or MRI, is particularly useful in differentiating benign from malignant masses, although definitive diagnosis requires histopathology. Overall, imaging is essential for diagnosis, staging, and surgical planning.

Cytology and histopathology are essential for definitive diagnosis of splenic hematoma. Fine-needle aspiration (FNA) of a splenic mass can be performed under ultrasound guidance. Cytology of a hematoma typically reveals blood, with few nucleated cells. However, FNA may not be diagnostic for hematoma, as it may only sample blood. In cases of hemangiosarcoma, cytology may show spindle cells with malignant features, but the diagnosis is often challenging due to the bloody nature of the sample. Histopathology is the gold standard for diagnosis. A splenectomy specimen should be submitted for histopathological examination. Grossly, a hematoma appears as a dark red, blood-filled mass with a fibrous capsule. Microscopically, a benign hematoma is characterized by organized blood clot with fibrin, hemosiderin-laden macrophages, and fibrous tissue. In contrast, hemangiosarcoma shows malignant endothelial cells forming irregular vascular channels, with areas of necrosis and hemorrhage. The mitotic index and cellular atypia are used to grade the tumor. Immunohistochemistry, such as factor VIII-related antigen or CD31, can confirm the endothelial origin of the tumor. Surgical margins should be evaluated to determine if the tumor has been completely excised. In cases of splenic hematoma, histopathology is crucial to differentiate benign from malignant lesions, as the treatment and prognosis differ significantly.

The treatment of splenic hematoma is primarily surgical, with splenectomy being the standard of care. Preoperative stabilization is essential, especially in cases of acute hemorrhage. Intravenous fluid therapy with crystalloids and colloids is administered to restore blood volume. Blood transfusion may be necessary in cases of severe anemia or coagulopathy. Once the patient is stabilized, surgery is performed. The surgical approach is a midline celiotomy. The spleen is exteriorized, and the splenic pedicle is ligated. The splenic artery and vein are double-ligated with absorbable suture material, such as polydioxanone (PDS) or polyglactin 910 (Vicryl), using a size appropriate for the vessel (e.g., 2-0 to 0). The omentum is dissected, and the spleen is removed. In cases of splenic torsion, the pedicle is untwisted before ligation. The abdomen is thoroughly lavaged with warm sterile saline to remove blood and debris. A closed-suction drain may be placed if there is significant contamination. Postoperative care includes pain management, antibiotics, and monitoring for complications. In cases of hemangiosarcoma, splenectomy is often palliative, and adjuvant chemotherapy with doxorubicin may be recommended. The prognosis for benign hematoma is excellent, while the prognosis for hemangiosarcoma is guarded to poor. Surgical techniques may vary depending on the extent of the disease, but splenectomy is the definitive treatment.

The prognosis for splenic hematoma depends on the underlying cause. For benign splenic hematomas, the prognosis is excellent, with a complete recovery expected after splenectomy. The median survival time for dogs with benign splenic hematoma is greater than 2 years, with many dogs living a normal lifespan. For splenic hemangiosarcoma, the prognosis is guarded to poor. The median survival time for dogs with splenic hemangiosarcoma treated with surgery alone is approximately 2 to 3 months. With adjuvant chemotherapy, the median survival time can be extended to 6 to 9 months. The presence of metastasis at the time of surgery is a negative prognostic indicator. Other negative prognostic factors include tumor rupture, large tumor size, and high histologic grade. The surgical success rate for splenectomy is high, with a low perioperative mortality rate (less than 5%) in stable patients. However, the complication rate is higher in patients with hemangiosarcoma due to the risk of DIC and metastasis. Functional recovery after splenectomy is generally good, as the liver and bone marrow can compensate for the loss of splenic function. Long-term monitoring is recommended for recurrence or metastasis, especially in cases of malignancy.

Postoperative follow-up for splenic hematoma includes monitoring for complications and, in cases of malignancy, surveillance for metastasis. The suture line from the celiotomy should be monitored for infection or dehiscence. Skin sutures or staples are typically removed 10 to 14 days after surgery. Activity should be restricted for 2 weeks to allow for healing. Serial abdominal ultrasonography is recommended at 1, 3, 6, and 12 months postoperatively to monitor for recurrence or metastasis. Thoracic radiography should be performed at the same intervals to evaluate for pulmonary metastasis. In cases of hemangiosarcoma, chemotherapy protocols may require regular blood work and veterinary visits. The patient's overall health and quality of life should be assessed at each visit. Long-term monitoring for splenic hematoma is essential, especially in cases of malignancy, to detect recurrence or metastasis early and initiate appropriate treatment.

Clinical pearls for splenic hematoma include: 1) Always consider splenic hematoma in the differential diagnosis of acute hemoperitoneum in large-breed dogs. 2) Preoperative stabilization is critical; do not rush to surgery in an unstable patient without attempting to stabilize with fluids and blood products. 3) During splenectomy, ligate the splenic artery and vein individually to prevent hemorrhage. 4) Use a self-retaining retractor to improve exposure of the spleen. 5) If the spleen is ruptured, control hemorrhage by applying digital pressure or using a vascular clamp before completing the splenectomy. 6) Submit the entire spleen for histopathology, even if it appears benign, to rule out malignancy. 7) In cases of splenic torsion, detorse the pedicle before ligation to prevent reperfusion injury. Pitfalls include: 1) Failing to stabilize the patient before surgery, leading to intraoperative death. 2) Incomplete ligation of the splenic pedicle, causing postoperative hemorrhage. 3) Iatrogenic rupture of the spleen during manipulation, leading to severe hemorrhage. 4) Missing a concurrent gastric dilatation-volvulus, which can be life-threatening. 5) Not performing histopathology, leading to a missed diagnosis of hemangiosarcoma. 6) Overlooking metastasis in the liver or lungs, which affects prognosis. 7) Inadequate postoperative pain management, leading to patient distress and delayed recovery.

Perioperative drug protocols for splenic hematoma are based on Plumb's Veterinary Drug Handbook. Prophylactic antimicrobials: Cefazolin (22 mg/kg IV) administered 30 minutes before surgery and repeated every 90 minutes during surgery. Postoperative antibiotics are not routinely needed unless contamination occurred. Analgesics: Preoperative opioids such as hydromorphone (0.05-0.1 mg/kg IV) or methadone (0.1-0.3 mg/kg IV) are used for pain management. Postoperative analgesia can be provided with a constant rate infusion (CRI) of fentanyl (2-5 mcg/kg/hr IV) or lidocaine (25-50 mcg/kg/min IV) and ketamine (0.1-0.5 mg/kg/hr IV) for multimodal analgesia. Nonsteroidal anti-inflammatory drugs (NSAIDs) such as carprofen (2.2 mg/kg PO q12h) or meloxicam (0.1 mg/kg PO q24h) can be used after the patient is hemodynamically stable. Local anesthesia: A line block with bupivacaine (1-2 mg/kg) at the incision site can provide additional analgesia. Muscle relaxants are not typically needed. Chondroprotectants are not relevant. In cases of DIC, fresh frozen plasma (10-15 mL/kg IV) may be administered. For hemangiosarcoma, doxorubicin (30 mg/m² IV every 3 weeks) is the most commonly used chemotherapeutic agent. Dosages should be adjusted based on organ function and patient status.

Evidence-based literature on splenic hematoma includes several landmark studies. A study by Spangler and Culbertson (1992) evaluated 1000 splenic masses in dogs and found that 50% were benign, with hematoma being the most common benign lesion. They reported that benign hematomas had a good prognosis after splenectomy. Another study by Johnson et al. (1989) compared the survival of dogs with splenic hemangiosarcoma treated with surgery alone versus surgery plus chemotherapy, showing a significant survival benefit with chemotherapy. A more recent study by Wendelburg et al. (2015) evaluated risk factors for perioperative mortality in dogs with splenic masses and found that hemangiosarcoma and preoperative hemoperitoneum were associated with higher mortality. The ACVS consensus statement on splenic masses recommends splenectomy for all splenic masses due to the high risk of malignancy and rupture. The use of adjuvant chemotherapy for hemangiosarcoma is supported by multiple studies, with doxorubicin-based protocols showing the best outcomes. Overall, the evidence supports early surgical intervention and histopathological evaluation for all splenic masses.