This prospective multicenter observational study aims to evaluate the diagnostic accuracy of the Testicular Workup for Ischemia and Suspected Torsion (TWIST) score in adult patients presenting with acute scrotal pain in Swedish Emergency Departments.

The TWIST score is a clinical decision tool originally validated in pediatric populations to stratify patients into low, intermediate, and high risk for testicular torsion. The study will include men aged 18-40 years presenting with scrotal pain or symptoms suggestive of torsion. Patients with scrotal trauma, symptom duration over one week, previous testicular surgery, or inability to give informed consent in Swedish will be excluded.

Participants' clinical findings will be recorded on a standardized form, and the TWIST score will be calculated. Management will follow standard clinical practice independently of the study. Primary outcome is the diagnostic accuracy of the TWIST score to rule out testicular torsion in low-risk patients (TWIST 0-2). Secondary outcomes include diagnosis of torsion within 30 days, time to surgery, patient-reported pain, number of Doppler ultrasounds performed, and the potential reduction in unnecessary imaging.

The study will be conducted at multiple Swedish sites, including Linköping University Hospital, under oversight by the Swedish Ethical Review Authority (Etikprövningsmyndigheten, decision number 2025-07400-01). The results aim to inform clinical practice by providing a validated decision-support tool for adult patients with suspected testicular torsion, potentially improving patient outcomes and resource utilization.

Acute scrotal pain is a common presentation in Emergency Departments, but the diagnosis of testicular torsion (TT) is relatively rare. Prompt identification is crucial because TT requires urgent surgical intervention to preserve testicular viability. Delays in diagnosis, particularly due to unnecessary imaging or non-standardized clinical assessment, may result in testicular loss.

The TWIST (Testicular Workup for Ischemia and Suspected Torsion) score is a clinical decision tool developed and validated in pediatric populations to stratify risk of TT based on five clinical features: testicular swelling, hard testis, high-riding testis, absent cremasteric reflex, and nausea/vomiting. Adult validation is limited, and no large-scale multicenter study has evaluated its performance in adult Emergency Department settings in Sweden.

This study will prospectively collect structured clinical data from adult patients aged 18-40 years presenting with scrotal pain at participating Swedish EDs. The TWIST score will be calculated from documented clinical findings. The study does not influence clinical management; patients will receive standard care, including imaging or surgical intervention as deemed appropriate by treating clinicians.

Primary objectives focus on the diagnostic accuracy of TWIST for ruling out TT in low-risk patients, while secondary objectives include assessment of the score in identifying high-risk patients, measurement of time to surgery, evaluation of pain scores, and analysis of imaging utilization. Data will also be linked to the Swedish Perioperative Register (SPOR) for outcomes such as surgery performed, complications, and final diagnoses.

The study is designed to evaluate whether structured use of TWIST can support evidence-based, standardized risk stratification in adults, potentially improving patient outcomes, streamlining resource use, and reducing unnecessary delays in diagnosis and treatment. Ethical oversight is provided by the Swedish Ethical Review Authority (Etikprövningsmyndigheten, decision 2025-07400-01).

Inclusion Criteria:

• Male patients aged 18-40 years

Presenting to the Emergency Department with acute scrotal pain or scrotal symptoms

Suspicion of testicular torsion before clinical assessment

Exclusion Criteria:

• Scrotal pain or symptoms caused by trauma

Symptom duration > 1 week

History of testicular surgery

Inability to provide informed consent (e.g., language barrier or cognitive limitation)

The study population consists of adult men aged 18-40 years presenting to participating Emergency Departments in Sweden with acute scrotal pain or scrotal symptoms suggestive of testicular torsion. Patients with trauma-related scrotal pain, symptom duration longer than one week, previous testicular surgery, or inability to provide informed consent are excluded. The study aims to evaluate the diagnostic accuracy of the TWIST score in a real-world adult ED population.

The study will collect sensitive health data from adult patients with acute scrotal pain. Due to patient privacy and data protection regulations, individual participant-level data will not be shared outside the research team.