Which test is best for assessing peritonitis in a patient who is unwilling to stand?

The heel jar test is particularly effective in assessing peritonitis for a patient who is unable or unwilling to stand. This test involves the patient being in a supine position while a sharp jar or thump to the heel is administered, which can elicit abdominal pain if peritoneal irritation is present. This is especially useful because it doesn't require the patient to be upright and is still able to provide significant information about potential peritoneal irritation.

In contrast, other tests may not be as suitable for this situation. For instance, the percussion test requires the practitioner to tap on the abdomen to detect fluid or gas collections, which can be challenging in a non-compliant or reluctant patient. The rebound tenderness test, which assesses for pain upon release of pressure on the abdomen, also would typically require the patient to be cooperative and take a position that might not be feasible in someone unwilling to stand. Similarly, the Markle test involves the patient standing on their heels and then allowing their heels to drop which could be impossible for an unwilling patient, making it less applicable in this scenario. Therefore, the heel jar test provides a viable option for assessing peritonitis in a patient who cannot stand.