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14yo boy presents with LLQ abdominal pain and left hip pain for 5 days. He has not had any fever. He is an active baseball player and skinned his right knee the week before. On exam, he prefers to keep his left hip flexed at 90 degrees, walks with a limp and lordosis, and is most comfortable laying on his right side with his hips flexed. He has LLQ abdominal tenderness and has maximal pain with any attempt to extend or internally rotate his left hip. Genitourinary exam is normal.
August 28, 2018 at 8:55 am
D) CT abdomen and pelvis. The patient’s presentation is concerning for psoas abscess, a relatively rare entity. Presentation is usually subacute, and patients may have back, abdominal, or groin pain, fever, and may even have urinary frequency. Patients usually present with hip flexion and lordosis, with pain on stretching the psoas muscle. Septic arthritis is in the differential, but plain radiographs are neither sensitive nor specific; evaluation typically occurs with labs (CBC, ESR or CRP) and ultrasound to look for joint effusion, then joint aspiration by a surgeon or interventional radiologist if highly suspected.
August 28, 2018 at 12:37 pm
If we are playing the odds, the top of the differential is septic arthritis, osteo or SCFE. Trauma, and no fever would place SCFE at the top of my list. Initial labs would be CBC, ESR, CRP and plain films.
If the plain films are negative (including frog and lateral), then move on to a more exotic diagnosis.
Starting with CT of abdomen and pelvis is significant radiation, expense, and wasted medical education (ie: anyone could order it!)
August 28, 2018 at 1:04 pm
Good point – It is probably reasonable to do a plain film to r/o avulsion fracture also. I should rewrite the question with a more clearly wrong choice…