The perineum is the area extending from the anus to the vaginal orifice in women and from the anus to the back of the scrotum in men. Rich in nerve endings, the strip of skin between the anus and testicles is an area in which men may feel discomfort for a variety of reasons, particularly during physical activity such as walking.
Pain resulting from prostatitis, or inflammation of the prostate, may be felt in the lower back, the genitals or the perineum. Prostatitis has a variety of causes, but is most often the result of bacterial infection. Pain or burning on urination or ejaculation, cloudy or bloody urine, and urethral discharge are some of the hallmarks of prostatitis, especially when found in conjunction with generalized symptoms of infection such as fever and chills. Prostate cancer, one of the most common carcinomas in men older than 50, is marked by many of the same symptoms. If you have pain near your testicles and anus along with these symptoms, see a physician immediately.
Trauma and Nerve Damage
The perineal branch of the pundendal nerves supplies sensory fibers to the area between the anus and testicles and is commonly entrapped, impinged upon or damaged. If while walking you experience burning, partial or total numbness, increased sensitivity, a shock-like sensation or stabbing pain, knife-like pain, the feeling of a lump or foreign body, twisting or pinching, or abnormal temperature sensations in the area -- especially if you have done a lot of sitting on an unusual surface recently -- you may have damaged your pudendal nerve and should be evaluated by a clinician.
Urinary Tract Infection
Although more common in women, urinary tract infections, or UTIs, can cause pain in the perineum on activity or at rest. As with prostate problems, bloody urine and unusual discharge are often seen, along with polyuria, or frequent urination. UTIs in men are more common in the elderly, especially in men who have recently had an indwelling catheter. As many UTIs originate in the kidney, a common finding is pus or white blood cells in the urine. A thorough urinalysis, or UA, is required for diagnosis, and treatment is with antibiotics.
Kidney stones, or renal calculi, are extraordinarily painful accretions of urate or phosphate crystals in the kidney. There are a wide variety of predisposing factors, including pancreatitis, derangements in blood or urine calcium or urate levels, heat exhaustion, excessive levels of various dietary components and metabolites such as oxalates and cysteine, and certain drugs. Pain can occur almost anywhere in the abdomen, not only in the perineum but in the lower back. Sometimes stones pass on their own, while at other times a procedure known as lithotripsy is required to dissolve them.