TAT is considered the most common cause of acute scrotum in children. Patients with TAT are usually younger than patients with TT and have also a longer duration of symptoms. Differential diagnosis with TT and epididymitis can be challenging [14, 21]. Mushtaq et al. reported a misdiagnosis rate of 12.5% in the case of TT, 17% for TAT, and 44% for epididymitis [22]. The literature remarks on the importance of US in enhancing the diagnostic power of clinical examination alone [23,24,25,26,27,28,29]. TAT’s clinical management is not homogenous across the world. Many surgeons prefer to attempt a conservative therapy with NSAIDs, thus leaving the surgical option only to those patients who do not respond to this strategy [16,17,18,19]. Others, as reported by Murphy et al., prefer to explore all cases of acute scrotum to minimalize testis damage [30]. In our center, we behave as the first ones when both clinical and US findings are strongly suggestive of TAT. To our knowledge, clinical or radiological signs that can predict a failure of conservative management are still missing. According to this lack of strong predictive factors in the literature, we retrospectively analyzed the clinical and US findings of our cohort of patients. The original idea was that twisted hydatid’s dimension could affect the response to conservative management because of a more difficult resorption and/or the greater inflammatory process involving the epididymis and testicular tunics, but no statistically significant results were observed. Another hypothesis we formulated is that, maybe, the later NSAIDs are started, the higher the risk of failure and, consequently, the chance of undergoing surgery: surprisingly, even if the operated group (group II) was diagnosed later than group I, the difference was not statistically significant. Summing up, NSAIDs have been successful in most patients (90%), even in those with very big, twisted appendages that received medical evaluation with a certain delay. On the contrary, our data suggested that cases that underwent surgery were the ones in which US documented a well-established epididymitis (p = 0.03), hydrocele (p = 0.03), or both (p = 0.02). Talking in terms of probability, according to our data, the chance of surgical intervention in the case of TAT when associated only with epididymitis without hydrocele is estimated to be 15%, when associated with hydrocele without epididymitis is 9%, with both epididymitis and hydrocele is 74%, and finally, an isolated TAT without epididymitis nor hydrocele has only a 2% chance of surgery (Fig. 2).

In other words, apparently, it does not matter how big the twisted appendix is nor the celerity of diagnosis, at least until the epididymis is significantly affected by an inflammatory process that associates with secondary hydrocele.

These results may suggest preferring a surgical first-line treatment in patients with TAT when presenting with both epididymitis and hydrocele.

Nevertheless, even if a more aggressive behavior is justified by the will of reducing the days of pain and discomfort of our little patients, looking carefully at our data, operating immediately all TATs with both epididymitis and hydrocele would determine a risk of 16% of unnecessary surgical treatment. This rate of avoidable procedures is too high in our opinion.

Moreover, an important limitation of our study is the too-subjective nature of the US description of epididymitis and hydrocele: if we accept that these findings may affect the surgical timing, we must ask radiologists to design a more objective description of these entities possibly with a severity grading scale. These struggles could reduce the number of unnecessary surgical interventions changing definitively the actual approach. Considering how US changed not only diagnostics but also operative procedures [23, 31,32,33] in the modern era, we believe surgeons should themselves dedicate to this technique and flank radiologists investigating the features we described in our paper.

Finally, what we can state with reasonable certainty after our analysis is that patients with TAT and associated hydrocele and epididymitis should be given a strict out-clinic follow-up due to the high risk of therapy failure.