After taking a sitz bath, the testicles swell, suggesting that the patient may have varicocele, orchitis, epididymitis and other conditions, and can seek medical attention to confirm the specifics. 1. Varicocele: due to various reasons, the function of venous valves is abnormal, leading to venous blood stagnation and inducing lesions. The common symptom of the patient is scrotal distension, and discomfort may occur in the perineum area, small abdomen, and lower back. After taking a sitz bath, it leads to local vasodilation, which may induce testicular distension. 2. Orchitis: It can be secondary to mumps, prostatitis and other lesions, bacteria, viruses and other disease-causing microorganisms invade the testicles, inducing inflammation, and testicular swelling and pain can occur. After taking a sitz bath, it can improve the blood circulation of testicles, and there will be vasodilatation, which may induce the symptoms of testicular distension. 3. Epididymitis: the cause is complicated, after the onset of the disease, the patient may also appear scrotal swelling discomfort. During sitz bath, it may induce testicular distension. After diagnosing the specific condition, patients can take medication or surgical treatment under the guidance of doctors, which can make the symptoms subside.