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Pulmonary Embolism Presenting with Right Flank Pain

Pulmonary Embolism Presenting with Right Flank Pain

Three women—all of whom presented with positional right flank pain— all had the same final diagnosis.

Case 1: A woman in her 30s with a history of asthma and migraines and a recent URI presents with a 3 day history of right flank pain, which she thinks is a muscle strain from lifting her 3-month old. The pain is worse with lying down and increased with respirations. She denies fever, hematuria, dysuria, vomiting, and shortness of breath. Her vitals and exam are essentially normal. Urinalysis shows 200 RBC’s. Chest film shows a faint right sided infiltrate.

Case 2: Another woman in her 30’s presents with 4 days of intermittent right flank pain that is positional. The pain is much worse when she is supine and is relieved by standing up. It has been intermittent, and lasts up to 20 minutes. It also seems like it is difficult for her to take a deep breath. She denies shortness of breath, fever, vomiting, hematuria and dysuria. She was seen at another ED yesterday, had a negative UA and was sent home with a diagnosis of biliary colic. Vital signs and physical exam are normal. UA is negative again today, as is the chest film.

pulmonary embolismCase 3: The third woman was referred to the ED by her pain specialist. She had “refractory” right flank and abdominal pain that had not been relieved by a cholecystectomy: the plan was to do an intercostal rib block Monday in the office. The pain is in the right flank and worse with inspiration and twisting movement or lying on her side. She also has had a cough productive of yellow phlegm and occasional blood, which she had been told was due bronchitis for which she recently finished a course of antibiotic. Her chest x-ray is shown (Figure).

Pulmonary embolism (PE) was diagnosed in all 3 patients. The diagnosis was made by VQ scan in 1 patient, and by CT angiogram in 2. Both angiograms demonstrated a lung infarction that had caused a small pleural effusion. The reason the pain was positional was most likely due to the pleural effusion, which moves with changes in position. A small effusion was also suspected in the patient whose PE was diagnosed by VQ.

The chest x-ray (Figure) shows an elevated right hemidiaphragm—one of many possible chest x-ray findings in the setting of pulmonary embolism. The Table lists other possibilities.

DISCUSSION
PE can cause a variety of clinical presentations. The classic presentation of dyspnea, tachypnea, and pleuritic chest pain may only be seen with PE’s that are mid-sized. Small PE’s tend to lodge distally in the pulmonary circulation where there is little to no collateral circulation and thus cause small peripheral lung infarcts that present primarily with pleuritic pain and occasionally hemoptysis. Dyspnea, and alterations in vital signs are unlikely with small PE’s. Large PE’s tend to lodge more centrally and due to collateral circulation are less likely to cause lung infarction. They are therefore often painless, but due to the degree of vascular obstruction are much more likely to cause dyspnea on exertion and alterations in vital signs, such as tachycardia, hypotension with or without syncope, tachypnea, and hypoxia. Large PE’s are also more likely to cause electrocardiographic changes and small elevations in troponin and BNP levels, which may often lead to misdiagnosis of a primary cardiac condition.

Testing for pulmonary embolism if full of pitfalls. Unnecessary testing can be time consuming and expensive and can expose your patient to large doses of ionizing radiation. On the other hand, a missed pulmonary embolism can be fatal and, as noted, many cases—particularly large or small PE’s— present somewhat atypically. Chest films may be normal or may show a variety of findings (see Table). It is most useful to rule out alternative diagnoses and to choose between a VQ scan and a CT angiogram as the diagnostic test.

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