A 66-year-old woman with a history of osteoarthritis presented to the emergency department with progressively worsening left hip pain that had started five days prior to arrival. The pain was non-radiating and worse with movement, and it was associated with chills and anorexia. She had progressive difficulty walking because of pain. She had not had similar symptoms in the past, and attributed her pain to osteoarthritis. She denied recent trauma, back pain, leg swelling, numbness, and paresthesias. She also denied fever, abdominal pain and distention, nausea, vomiting, diarrhea, constipation, urinary symptoms, allergies, alcohol, and drug use.
She was a well-appearing obese woman in no acute distress. Her blood pressure was 158/100 mm Hg, and her temperature was 100.2°F. She had left lower quadrant abdominal tenderness without distention, guarding, or rigidity; she also had no costovertebral angle tenderness, hernias, or masses. Her pain was greatest with active range of motion of the left hip. The remainder of her physical exam was unremarkable.
The patient's white-cell count was 16,140 per cubic millimeter without a left shift or bandemia. X-rays of left hip and pelvis were unremarkable. A non-contrast CT of the abdomen and pelvis was obtained because of her abdominal tenderness. The CT revealed a 3.9 cm fine linear foreign body within a loop of small bowel in the upper pelvis that appeared to extend through the lateral wall abutting the adjacent left psoas, causing a psoas abscess. (Photo.)
The emergency physician suspected the foreign body might be a fish bone, and the patient revealed that she frequently ate fish with bones. The patient was started empirically on ertapenem, and surgery was consulted. She was taken for an exploratory laparotomy, and had extensive lysis of adhesions, a small bowel resection, and drainage of the psoas abscess. A culture of the abscess specimen grew Klebsiella pneumoniae, and intravenous antibiotics were continued for several days. The patient's symptoms resolved, and she was discharged home on cefpodoxime and metronidazole. She recovered well.
Psoas abscess is a rare condition with high morbidity and mortality. The clinical manifestations are often variable and nonspecific, which makes it difficult to diagnose on physical exam alone. Symptoms include malaise, anorexia, weight loss, nausea, back pain, and abdominal pain. The classical clinical triad consisting of fever, back pain, and a limp is present in only 30 percent of the patients with a psoas abscess. (Postgrad Med J 2004;80:459.) The diagnosis could be even more challenging when the patient also has a history of arthritis, lumbar strain, vertebral osteomyelitis, or abdominal/urologic disorders suggesting an alternative pathology. This can lead to a delayed diagnosis that carries a much higher mortality. (Am J Emerg Med 1997;15:83.) A high index of suspicion and a detailed history are crucial for the correct diagnosis. CT is the optimal radiographic modality; laboratory testing is unreliable in diagnosing psoas abscess.
Psoas abscess in the United States is usually caused by other disease processes, with Crohn's disease being the most common, followed by appendicitis, nephrolithiasis, diverticulitis, and colon cancer. Most patients tend to be older, and often have poorer outcomes, with mortality approaching 20 percent. (Am J Emerg Med 1997;15:83.) Only two case reports have described psoas abscesses caused by duodenal perforation from foreign bodies (toothpick and wooden skewer.) (Aust N Z J Surg 1992;62:662;G Chir 2008;29:180.)
Psoas abscesses caused by Klebsiella pneumoniae also carry a higher mortality rate because of their ability to form gas and the increased risk of septic metastasis, including to the aorta. Early recognition and prompt drainage or debridement are essential, and should be performed in a timely manner. (J Microbiol Immunol Infect 2001;34:201.) This is especially relevant when patients have a history of diabetes mellitus or alcoholism because these disease processes predispose the patient to infection with this organism.
Psoas abscess is an uncommon etiology of hip pain that is easy to overlook because of its rarity. This case differs from an isolated case of a psoas abscess because a foreign body was seen within the small bowel wall adjacent to left psoas muscle, causing the abscess. Physicians need to maintain a high index of suspicion for a psoas abscess because its signs and symptoms are highly nonspecific, and delaying the diagnosis may be fatal.