Is there a twist to the TWIST score?
Evaluating the clinical score for diagnosis and exclusion of testicular torsion
The TWIST (Testicular Work-up for Ischemia and Suspected Torsion) score is a tool that has been validated for use in the diagnosis or exclusion of testicular torsion in children. The tool affords a different number of points to different aspects of a physical exam that may suggest testicular torsion in order to aid in provider suspicion of the diagnosis. The score is as follows: (2pts) for testicular swelling, (2pts) for a hard testicle, (1pt) for an absent cremasteric reflex, (1pt) for nausea or vomiting, and (1pt) for a high-riding testicle. With the current use of the tool, a score greater >5pts has been shown to have a 100% positive predictive value (PPV) whereas a score <2pts has been shown to demonstrate a negative predictive value (NPV) of 100% as well.
The typical presentation of testicular torsion involves an adolescent male with an abrupt onset of severe pain and swelling within a testicle, often accompanied by nausea and vomiting. On physical exam, an asymmetric, high-riding testicle is exquisitely tender to palpation. To differentiate from epididymitis, one may assess if lifting the affected testes relieves the pain (Prehn sign) which would be negative, and still cause pain, in an individual with torsion. Also important to the assessment for testicular torsion, is the presence or absence of the cremasteric reflex on the side of the affected testicle. The cremasteric reflex is elicited by stroking of the inner thigh on the affected side and observing for testicular contraction. Diagnosis of testicular torsion is confirmed by Doppler US of the affected testes demonstrating lack of blood flow.
While the TWIST score has been validated for use in making the diagnosis of torsion, the 1pt afforded to an absent cremasteric reflex is interesting to say the least. While the classic teaching is that an absent cremasteric reflex is highly specific and sensitive for torsion, more recent studies have conflicting data that show torsion present even with a present cremasteric reflex. This certainly goes against the classic teachings I experienced in school but would support the reasoning for only one point being awarded to this test when calculating the TWIST score.
On the flip side, if the only physical finding is an absent cremasteric reflex and therefore per the TWIST score would not recommend obtaining ultrasound, I personally feel that this could result in many missed testicular torsion.
Please let us know your thoughts on the TWIST score and your approach to torsion by emailing us directly or commenting below!