A 26-year-old previously healthy man is brought to the emergency department after a motor vehicle collision. The patient was driving while wearing a seatbelt when his car was hit on the left side by another vehicle. He has since had persistent left shoulder pain. He also has nausea and hiccups. The patient's blood pressure is 90/60 mm Hg and pulse is 115/min. On examination, he has a bruise on the left lower chest wall with tenderness to palpation along the area. Chest auscultation reveals normal heart sounds and bilaterally equal breath sounds. He has a rigid and tender abdomen. Which of the following is the most likely diagnosis?
This patient's rigid abdomen with associated left shoulder pain, hypotension, and tachycardia suggests a possible splenic laceration and hemoperitoneum. The shoulder pain likely represents referred pain due to peritoneal irritation (Kehr sign).
The phrenic nerves originate from C3-C5 and pass between the lung and heart to provide motor function to the diaphragm. The phrenic nerves also provide sensory fibers to the pericardium, mediastinal pleura, and diaphragmatic peritoneum. The supraclavicular nerves originate from C3-C4 and their branches innervate the sternoclavicular joint, local muscles (eg, sternocleidomastoid), and the skin of the upper and posterior shoulder. Any abdominal process (eg, ruptured spleen, peritonitis, hemoperitoneum) irritating the sensory fibers around the diaphragm can cause referred pain via the phrenic nerve to the C3-C5 shoulder region. Phrenic nerve irritation can also cause hiccups due to spasmodic diaphragmatic contraction pulling air against a closed larynx.
(Choice A) Traumatic aortic rupture presents with chest wall contusions and hypotension, but it is not typically associated with persistent left shoulder pain or hiccups.
(Choices B and D) Hemopericardium (blood accumulation in the pericardial sac) typically presents with shortness of breath, tachycardia, jugular venous distention, and possible hypotension. Lung contusion usually presents gradually with shortness of breath, chest pain, and consolidation on lung imaging. However, persistent shoulder pain is not commonly associated with either condition.
(Choice C) Humerus fracture typically presents with acute shoulder pain that is increased with movement. Examination can show a deformed shoulder joint. This patient's rigid abdomen and absence of obvious shoulder abnormalities make this less likely.
(Choice E) Myocardial contusion after chest wall trauma typically presents with mid-anterior chest wall pain, shortness of breath, persistent tachycardia, and new conduction defects on ECG (eg, bundle branch block). It is not typically associated with persistent abdominal or shoulder pain.
(Choice F) Pneumothorax after chest trauma usually presents with tachypnea, shortness of breath, decreased or absent breath sounds, unilateral hyperresonance to percussion, and pleuritic chest pain. This patient's bilaterally equal breath sounds make this unlikely.
Educational objective:
Any abdominal process (eg, ruptured spleen, peritonitis, hemoperitoneum) irritating the phrenic nerve sensory fibers around the diaphragm can cause referred pain to the C3-C5 shoulder region (Kehr sign).