Laboratory Studies
Laboratory studies are not required to make the diagnosis, but some may be helpful in eliminating other causes. A complete blood count (CBC) should be obtained to rule out systemic infection. Leukocyte counts should be normal; if not, infectious causes should be sought. The erythrocyte sedimentation rate (ESR) should be measured to rule out possible inflammatory and rheumatologic disorders. A urinalysis should be performed to rule out an etiology of a urinary tract infection (UTI) or prostatitis.
If the patient is febrile, perform a blood culture. Most of the time, the blood culture will be negative, unless the patient presents as clinically septic. Patients with osteomyelitis will most likely have blood cultures that are positive for S aureus.
Plain Radiography
Radiographs are often negative early in osteitis pubis. After a few (typically approximately 4) weeks, some widening of the pubic symphysis may be seen on anteroposterior (AP) films (see the image below). As osteitis pubis progresses, sclerosis and osteolysis can be seen. In the case of osteomyelitis, bone erosions can be seen on plain films.
Radiograph in 19-year-old athlete who presented with 3-week history of groin pull that was not resolving. On clinical examination, pubic spring test reproduced patient's pain, and radiograph was obtained. This image shows classic sclerosis and lysis findings of osteitis pubis around pubic symphysis, with widening of symphysis.
If pelvic inequity is suspected as a cause, flamingo views can expose a pubic instability. Instability is defined as more than 2 mm of cephalad translation of the superior pubic ramus on each side, with the patient standing on 1 leg in turn. The sacroiliac joints also should be evaluated; since laxity of one or both may contribute to pubis symphysis instability.
Bone Scanning, SPECT, MRI, and CT
Bone scanning (technetium-99m [99m Tc]) or single-photon emission computed tomography (SPECT) may be negative but often yields positive results early in the disease. These studies show increased radionuclide uptake directly over the pubic symphysis or unilaterally at the pubic margin. The delayed views of the triple-phase bone scan are conclusively positive in cases of osteitis pubis. However, the degree of positivity or unilateral findings does not correlate well with the severity of the symptoms or the chronicity of the disease. [4]
As magnetic resonance imaging (MRI) becomes more widely used and the technology more sophisticated, its utility increases (see the image below). [15, 26, 27, 28, 29] MRI is especially useful when fat suppression views are obtained, in that it helps the physician distinguish among muscle, tendon, periosteal, and bony disruption. Often, inflammation of the fibrocartilaginous disk, bone marrow edema, and sclerosis at the pubic margins can be appreciated, [30, 26] though bone edema is also seen in asymptomatic individuals. [31]
Magnetic resonance image (MRI) from 20-year-old National Hockey League (NHL) player who presented with complaint of pain in testicles, which was worse with skating and with performing off-ice plyometric conditioning. MRI of pelvis combined with history and physical examination indicated diagnosis of osteitis pubis.
MRI has high sensitivity in distinguishing between acute and chronic osteitis pubis. In acute cases, MRI can reveal subchondral edema of the bone, which usually affects both sides. In chronic osteitis pubis, MRI findings can include periosteal reaction, bone resorption, irregularity of the articular surface, osteophytes, and subchondral cyst formation. [32]
Computed tomography (CT) is also used for evaluation of the pubis symphysis and the posterior pelvic ring.
Other Studies
In cases where the patient is febrile but the blood cultures are negative, the pubic symphysis should be aspirated for culture. This is most commonly done with the guidance of ultrasonography or CT scanning.
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Radiograph in 19-year-old athlete who presented with 3-week history of groin pull that was not resolving. On clinical examination, pubic spring test reproduced patient's pain, and radiograph was obtained. This image shows classic sclerosis and lysis findings of osteitis pubis around pubic symphysis, with widening of symphysis.
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Magnetic resonance image (MRI) from 20-year-old National Hockey League (NHL) player who presented with complaint of pain in testicles, which was worse with skating and with performing off-ice plyometric conditioning. MRI of pelvis combined with history and physical examination indicated diagnosis of osteitis pubis.
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Pelvis, frontal view.
