Mononucleosis (mono) is a common viral infection primarily caused by the Epstein-Barr virus (EBV). Mono is known for its association with an enlarged spleen, a complication that warrants careful attention.
How Mononucleosis Affects the Spleen
The spleen, located in the upper left abdomen, plays a significant role in the immune system by filtering blood and producing white blood cells. During a mono infection, the Epstein-Barr virus triggers an immune response, leading to an increase in lymphocytes and other cells. These accumulate within the spleen, causing it to swell and enlarge, a condition known as splenomegaly.
This enlargement can cause the spleen to become considerably larger than its normal size, sometimes increasing by three to four times. As the spleen expands, its outer capsule, usually quite resilient, can become stretched and thinner. This makes the enlarged spleen more fragile and vulnerable to injury, even from minor trauma or increased abdominal pressure.
Understanding the Risk of Splenic Rupture
Despite the spleen’s increased fragility during mono, a splenic rupture is an uncommon complication, occurring in 0.1% to 0.5% of individuals with mononucleosis. While rare, spontaneous rupture, meaning without direct trauma, can occur, though it is even less frequent, estimated between 0.06% and 0.5% of cases. Such an event can be life-threatening and represents the most serious complication of infectious mononucleosis.
The period of heightened risk for splenic rupture generally occurs within the first few weeks of the illness, peaking around two to three weeks after symptoms begin. However, splenic injuries have been observed up to eight weeks into the illness, highlighting the importance of continued caution.
Signs of a Ruptured Spleen
Recognizing the signs of a ruptured spleen is important for immediate medical intervention. The most prominent symptom is sudden, severe pain in the upper left abdomen, which may worsen with deep breathing.
Another specific indicator is pain felt in the left shoulder, known as Kehr’s sign. This referred pain occurs because blood from the ruptured spleen can irritate the diaphragm, and the nerves serving the diaphragm share connections with those supplying the shoulder. Additional symptoms that suggest internal bleeding include lightheadedness, dizziness, a rapid heart rate, and pallor, indicating potential hypovolemic shock. These symptoms necessitate immediate emergency medical attention.
Precautions and Recovery
To minimize the risk of splenic rupture, individuals diagnosed with mono should avoid activities that could cause abdominal trauma or significantly increase abdominal pressure. This includes refraining from contact sports, heavy lifting, and any strenuous physical exertion.
Recommendations for activity restrictions typically range from three to four weeks, or until a healthcare provider clears the individual. Some guidelines suggest an avoidance period of up to eight weeks, particularly for high-risk activities, or until an ultrasound confirms the spleen has returned to its normal size.
Listening to one’s body and allowing for adequate rest are important components of recovery. Resuming physical activities should be a gradual process and only undertaken after a doctor’s evaluation. This individualized approach helps ensure the spleen has healed sufficiently, reducing the chance of complications and supporting a safe return to daily routines.