The spleen is an encapsulated hematopoietic organ that lies within the posterior aspect of the left upper quadrant in the peritoneal cavity. It has proximity to the 9th, 10th, and 11th ribs; left kidney; stomach; transverse and descending colon; left hemidiaphragm; and the pancreas. The spleen is the visceral organ most frequently injured in blunt abdominal trauma. Trauma is also the most common cause of a ruptured spleen. In patients who experience non-traumatic splenic rupture, 7% are due to idiopathic causes, with the remaining 93% attributed to pathological causes.
Splenic rupture can be divided into two major categories: traumatic and non-traumatic rupture. The most prevalent major mechanism in traumatic injury (50% to 75%) is the result of motor vehicle injury. Direct abdominal blows and falls are the remaining major causes of traumatic rupture. Additionally, traumatic rupture can present immediately after an injury or may present in a delayed fashion. Non-traumatic splenic rupture is very uncommon, though can be related to underlying pathologic conditions or may be idiopathic. However, non-traumatic rupture, when it does happen, carries a mortality of around 12%. One often cited example of spontaneous splenic rupture, which occurs in only 0.1 percent of patients with this condition, is related to infection with mononucleosis.
The prevalence of splenic ruptures is not widely reported in the literature. The mechanism of the majority of traumatic ruptures continues to be motor vehicle injury, followed by direct abdominal blows. Sports such as football, hockey, and bicycling increase the risk of abdominal, and, therefore, splenic injury and rupture. One study suggests that traumatic splenic ruptures are more likely to occur in males (2:1 male to female) in ages ranging from 18 to 34 years. 
The following are six major causes of non-traumatic rupture:
Given that the spleen is a highly vascularized organ, significant blood loss can occur from either the parenchyma or the vascular supply to the spleen. The spleen serves the following significant functions :
A healthy adult spleen can weigh up to 250 gm and measure up to 13 cm long. Over time, it spontaneously involutes and may not be palpable in adults.
Trauma is the most common mechanism of injury, and blunt trauma involving the left-upper quadrant, left rib cage, or left flank should raise suspicion for splenic involvement. The absence of substantial trauma cannot exclude the possibility of splenic injury, as individuals with a history of splenomegaly require less force for traumatic rupture.
It is important to ask focused questions regarding previous surgical history, hepatic disease process, recent infections, anticoagulant, aspirin or nonsteroidal anti-inflammatory usage and bleeding disorders. Visual inspection for signs of external trauma such as abrasions, lacerations, contusions, and classic seatbelt sign on the abdomen is helpful. The absence of external visual findings does not exclude intra-abdominal pathology, as up to 20% of patients with intra-abdominal injury may not display these findings upon initial examination. Also, examination on arrival may not reveal severe tenderness, rigidity, or abdominal distention in spite of rupture. Physical examination may also be limited in a patient with altered mental status or distracting injuries. Therefore, the physical exam alone is not always sensitive when evaluating a patient with a splenic rupture.
Severally ill patients may present with hypovolemic shock manifesting as tachycardia, hypotension, and pallor. Other findings include tenderness to palpation in the left upper quadrant, generalized peritonitis, or referred pain to the left shoulder (Kehr sign). Kehr sign is a rare finding and should increase the suspicion of the peritoneal process and possible splenic rupture. Some patients also report pleuritic left-sided chest pain in the setting of a ruptured spleen. Caution should be used early in the evaluation of patients with a concerning mechanism of injury, since few symptoms may be present early in the course of splenic rupture.
Evaluation for splenic injury is therefore warranted if left lower rib fractures are identified. Up to 20% of adults with left lower rib fractures may have a subsequent splenic injury. The chest wall plasticity in children makes severe underlying injury to the spleen a possibility in the absence of rib fracture.
A splenic injury may not always be clinically apparent, and spontaneous splenic rupture or pathologic splenic rupture can occur after negligible trauma or insignificant events. 
Ultrasound can be very helpful and highly accurate in the diagnosis of significant splenic injury but is limited in detecting active bleeding, pseudoaneurysm, or early in the evaluation when blood loss is minimal. However, ultrasound at the bedside in the emergency department has been able to visualize as little as 100 mL of free fluid in the abdomen with 90% sensitivity. CT has become the mainstay of stable patient evaluation since it can provide splenic injury severity and assessment of other abdominal organs. An intraparenchymal or subcapsular hematoma is also easier to identify and may be associated with delayed splenic rupture.
Splenic injury is classified based on CT findings according to the American Association for the Surgery of Trauma (AAST) Organ Injury Scale. It helps categorizes splenic injuries but does not predict the need for surgical intervention.
Treatment is dependent on the severity and etiology of rupture, as well as the hemodynamic stability of the patient.
Non-operative treatment is attempted in 60% to 90% of patients with blunt traumatic splenic injuries out of a desire to preserve splenic function. A landmark 1968 case-control study on operative vs. non-operative management by Upadhyaya and Simpson suggested that isolated splenic injuries could be safely treated without surgery in children. Since that case, multiple studies have demonstrated similar outcomes, and non-operative management is the main management option, particularly in the pediatric population. Current success rates of 90% are reported in pediatric populations. 
Interventional radiology may be available at some institutions as a means to perform arterial embolization for large or small vessel injuries with bleeding in stable trauma patients. This is also an option in patients who fail conservative management.
Exploratory laparotomy is, however, indicated if continuing hemodynamic instability or if the patient has required more than 4 units of blood during a 48-hour period. The initial choice in surgical management is to repair any capsular lacerations (splenorrhaphy). If extensive injury or uncontrolled hemorrhage is present, splenectomy is warranted. Post-splenectomy vaccinations are intended to address encapsulated organisms ( Streptococcus pneumoniae, Haemophilus influenzae, and Neisseria meningitides.). Children who have a splenectomy are generally recommended to take phenoxymethylpenicillin (Pen VK) until they are 5 years old, though the recommended duration of this prophylaxis varies. This is based on a prior study of sickle cell patients.
Isolated left shoulder pain following an motor vehicle accident may indicate spleen rupture, especially in the absence of visible trauma to the left clavicle or shoulder. This is due to the innervation of the diaphragm which sits above the spleen in the left upper quadrant (Kehr sign).
Pancreatitis may lead to atraumatic splenic rupture.
Domestic violence should be among the considerations in evaluating patients with splenic rupture.
Malaria also remains a risk factor for splenic rupture in countries where this disease is prevalent.
A patient with splenic rupture may change in status from stable to unstable over the course of 24 to 48 hours. Thus these patients should be should be observed in the hospital.