Leg Pain (cont.)
How Do Health-Care Professionals Diagnose Leg Pain?
The evaluation of leg pain always begins with the health-care provider interviewing the patient and performing a physical examination to help determine the potential cause of the leg pain. The decision about diagnostic testing, including blood tests and X-rays, depends upon the provider's concern as to what the cause of the leg pain might be. Sometimes testing and X-rays are not required.
Blood tests including a white blood cell count, an erythrocyte sedimentation rate (ESR), and a C-reactive protein (CRP) measurement may help detect an infection. These are nonspecific tests that may give further direction to the health-care provider. Please note that the white blood cell count may be elevated with an infection unless the patient has an immune system that is compromised, at which point it may be falsely normal. As with all tests, the ESR and CRP, if elevated, need to be interpreted in light of the specific illness that is being considered.
If gout is a consideration, a blood test to measure uric acid may be done; however, in the acute attack, the uric acid level may be high, low, or normal. The result is helpful if the level is high and may confirm a gout flare if supported by the history and physical examination.
Other blood tests may be considered depending upon the underlying medical illnesses being considered.
- X-rays: If there is concern that a fracture or broken bone is present, plain X-rays may be indicated. As well, X-rays may be taken as a screening to look for fluid or calcifications in a joint.
- Ultrasound: An ultrasound may be helpful in making the diagnosis of deep vein thrombosis. Superficial vein thrombosis is usually diagnosed clinically based upon the physical examination, and no imaging may be required.
- Ankle-brachial index (ABI): Arterial blood flow in the legs may be assessed by an ankle-brachial index, in which blood flow is evaluated at rest and with exercise. This test involves comparing the blood pressure in the arms to the blood pressure in the legs.
- Arteriogram: If further information is needed about the arteries, an arteriogram may be performed to look directly at the arterial supply to the legs. This is accomplished by injecting contrast dye directly into the arteries and watching it flow through the arteries in the legs via X-rays. Arteriography may also be performed using CT or MRI studies (see below).
- CT scan: Computerized tomography (CT) may be used in a variety of situations. CT angiography may be able to take the place of arteriography is some situations to examine blood vessels. CT may also be used to evaluate bone and joint anatomy, looking for hidden fractures.
- MRI: Magnetic resonance imaging (MRI) may be used to examine the back for the causes of sciatica to evaluate bones, joints, and soft tissues such as muscles, tendons, and ligaments. MRI angiography may also be considered in place of formal angiography to evaluate blood vessels in the body. MRI is also of use in looking for hidden or occult fractures.
- Nerve conduction studies: Nerve conduction studies may be considered to evaluate nerve function and measure the ability of specific nerves to carry electrical impulses. This is helpful in deciding whether nerve pain is due to a central cause from the brain or spinal cord or due to a peripheral nerve injury. (For example, inflammation of the ulnar nerve from hitting the funny bone can cause the ring and little fingers to go numb and is not caused by a stroke.)
- Joint aspiration: If there is concern about infection or inflammation within a joint, a needle may be put into the joint to pull out or aspirate fluid for analysis. Often this fluid is sent to a laboratory to analyze the white blood cell count within the fluid (an elevated white blood cell count may signal inflammation), a gram stain and culture looking for bacterial infection, or crystal analysis looking for uric acid or calcium pyrophosphate crystals to make the diagnosis of gout or pseudogout, respectively.
- Compartment pressures: If compartment syndrome is suspected, compartment pressures may be obtained of the muscular compartments of the leg and/or thigh. Elevated compartment pressures may indicate the presence of compartment syndrome. This is an emergency situation that may require surgical release (incision) of the affected compartment(s) to relieve the elevated pressure and restore blood flow and nerve function.
Medically Reviewed by a Doctor on 12/15/2015
Patient Comments & Reviews
The eMedicineHealth doctors ask about Leg Pain: