What is the most likely diagnosis for a boy who presents with fever, abdominal pain, and distension, particularly on the right side, after a fall on his right side, and is found to be pale and hypertensive?

Most Likely Diagnosis: Liver Contusion

The most likely diagnosis is liver contusion (Option A), given the clear traumatic mechanism of a fall on the right side followed by progressive right-sided abdominal distension, pallor indicating hemorrhage, and compensatory hypertension.

Clinical Reasoning Based on Trauma History

The traumatic mechanism is the critical distinguishing feature in this case:

• The fall onto the right side directly implicates traumatic injury rather than spontaneous pathology, which immediately prioritizes liver contusion over non-traumatic diagnoses like pyelonephritis, neuroblastoma, or Wilms tumor 1

• Liver contusion from blunt abdominal trauma characteristically presents with delayed symptoms as bleeding accumulates, perfectly explaining why the child appeared relatively stable immediately after the fall but developed progressive distension by the next day 1

Physical Examination Findings Support Hepatic Hemorrhage

The constellation of clinical signs points specifically to significant hepatic injury with ongoing bleeding:

• Pallor indicates substantial blood loss from hepatic injury, which is expected given the liver's high vascularity and propensity for significant hemorrhage even with moderate trauma 1

• Hypertension in a pale child represents a compensatory catecholamine surge attempting to maintain perfusion despite hemorrhage, not true hypertension—this is a critical physiologic response to blood loss 1

• Right-sided abdominal distension suggests either subcapsular hematoma or intraperitoneal bleeding from hepatic injury, as the liver occupies the right upper quadrant and blood accumulation would manifest on that side 1

• Fever occurring 24-48 hours post-injury is consistent with liver contusion due to blood resorption, tissue necrosis, or developing hematoma 1

Why Other Diagnoses Are Excluded

Pyelonephritis (Option B):

• Does not explain the traumatic mechanism, pallor from blood loss, or specifically right-sided abdominal distension 1
• Would not cause compensatory hypertension from hemorrhage

Neuroblastoma (Option C):

• Develops over weeks to months as a gradually enlarging mass, not acutely after trauma 1
• The temporal relationship to trauma excludes this diagnosis

Wilms Tumor (Option D):

• Presents as a gradually enlarging abdominal mass over time, not acute post-traumatic distension 1
• No relationship to traumatic injury

Immediate Management Approach

In any child with abdominal pain, distension, and pallor following trauma, solid organ injury (especially liver or spleen) must be the primary consideration 1:

• Immediate contrast-enhanced CT imaging is indicated to assess for hepatic laceration, subcapsular hematoma, or intraperitoneal hemorrhage 1
• Resuscitation with IV access and blood product availability should be initiated while imaging is obtained
• Surgical consultation should be obtained immediately given the signs of significant hemorrhage

Critical Clinical Pearl

The combination of trauma history + delayed presentation + right-sided findings + signs of hemorrhage (pallor) + compensatory response (hypertension) creates a pathognomonic picture for liver contusion that cannot be explained by any of the other options 1.