costal margin tenderness: indication for abdominal CT?

STUDY 1:
--Do patients with pain or tenderness to the left lower ribs after blunt traumatic injury require abdominal computed tomography (CT) scanning for the detection of splenic injury?

875 patients had left lower rib pain or tenderness
--63 (7.2%; 95% confidence interval [CI] 5.6% to 9.1%) patients had splenic injuries
--20 (2.3%; 95% CI 1.4% to 3.5%) patients had left renal injuries

301 (of 875 total) patients had "isolated" left lower rib injury (i.e. no other reason to get a CT)
--9 (3.0%; 95% CI 1.4% to 5.6%) had splenic injuries
--All 9 patients had a pleuritic component to their rib tenderness, and 3 (33%) patients underwent splenectomy

--"A small but important percentage of patients with pain or tenderness to the left lower ribs has splenic injuries. All patients with splenic injury had pleuritic pain."


STUDY 2:
--derive and validate clinical prediction rules to identify adult patients at very low risk for intra-abdominal injuries after blunt torso trauma

derived rule for the presence of any intra-abdominal injury:

• GCS < 14
• costal margin tenderness
• abdominal tenderness
• femur fracture
• hematuria >= 25 RBCs/HPF
• hematocrit < 30%
• abnormal CXR (pneumothorax or rib fracture)

--sensitivity 137 of 143 (95.8%; 95% CI 91.1% to 98.4%)
--specificity 434 of 1,452 (29.9%; 95% CI 27.5% to 32.3%)
--negative predictive value 434 of 440 (98.6%; 95% CI 97.1% to 99.5%).

--"Patients without any of these variables are at very low risk for having intra-abdominal injury, particularly intra-abdominal injury requiring acute intervention, and are unlikely to benefit from abdominal computed tomography scanning"


BOTTOM LINE:
--2-7% those with left lower rib/costal margin pain can had splenic injury
--consider abdominal CT if patient with blunt trauma has left costal margin pain, particularly if pleuritic


Reference(s): study 1, study 2, picture