The Psoas sign is an indication that the iliopsoas muscle is irritated. The iliopsoas muscle is responsible, along with other muscles, for the flexion of the hips, being located at the level of the abdomen. In the medical literature, it is also known as the Obraztsova’s sign. The psoas test can be performed in order to identify the inflammation of the appendix or in case of pelvic pain. The doctor might also decide to perform the psoas test in patients who complain of low back pain.
How to perform Psoas sign?
In order for the psoas test to be performed, the patient has to lie on his/her side, with the knees extended. From this position, the doctor will try to passively extend the thigh. The doctor can also make the patient to perform the active flexion of the thigh on the hip.
Positive Psoas sign
The psoas sign is considered positive if abdominal pain results from the above mentioned movements. The pain occurs as the iliopsoas muscle is located in the retroperitoneal cavity; given that fact, the movements suggested earlier – the hyperextension of the hip performed passively or the active flexion of the thigh on the hip – will contribute to the appearance of pain, as the tissues in the area are inflamed.
As you will see below, the positive psoas sign is an indication of appendicitis. However, this sign is encountered in other medical problems as well, such as the abscess at the level of the psoas. If there are other factors leading to the irritation of the retroperitoneum, such as the hemorrhage of a major blood vessel (iliac vessel), the psoas sign might be positive as well. Among the other factors that contribute to the appearance of a positive psoas sign, you can also find: extrapelvic abscess, adnexal changes and different adhesions at the levels of the bowels.
If the patient suffers from peritonitis (caused by the rupture of the inflamed appendix), the doctor will also search for other signs. The abdomen might be rigid upon palpation and the patient might also suffer from high-running fever. In case of an iliac abscess, apart from the positive psoas sign, the doctor can also palpate a mass in the abdomen or in the pelvis.
In children, the psoas test can be performed by asking the child to raise their head, while applying pressure to their forehead. It is important to remember that the psoas sign is difficult to be elicited in patients who are older; in some of these patients, it does not appear. The doctor performing the psoas sign test should be experienced enough, so as to be able to make the difference between the positive psoas sign and the joint or musculoskeletal pain due to aging.
Psoas sign in Appendicitis
The psoas sign can be used to determine the inflammation of the appendix. The right iliopsoas muscle is located right under the appendix, with the patient maintaining the supine position. The identification of a positive psoas sign might mean that the patient is suffering from acute appendicitis, requiring surgical intervention.