Sex position, despite the lack of knolwedge in medicine by physicians and patients could be a health risk and precipitates significant medical problems or disorders such as “Urethral Stricture” in men!  Urethral stricture may cause difficulty and pain in urination, tenderness, sensitivity and pain along the urethral path, mostly from the scrotum down, particularly in penis, burning sensation on urination and at the penis glans, urinary tract infection, decreased force of urinary stream, incomplete emptying of the bladder and urinary retention, urinary terminal dribbling and intermittency, increased frequency of micturition and urgency, etc.

Urethral stricture is a relatively common disease in men with an associated prevalence of 229-627 per 100,000 males, or 0.6% of the at risk population, who are typically older men, over 55-65 years of age. Data from Medicare and Medicaid Services (for patients older than 65 years) confirmed an increased incidence of stricture disease at 9.0/100,000 for 2001 compared to 5.8/100,000 in patients younger than 65 years. There is a high health care cost for treatment of urethral stricture with an estimate of 191 million dollars in 2000 in US. The vast majority of strictures occurring in the anterior urethra (92.2%), in particular the bulbar urethra (46.9%).

As it is shown in the image below,The male urethra is divided into the anterior and posterior urethra. The posterior urethra consists of the segment that extends from the bladder neck to the distal external urethral sphincter and can be divided into the prostatic urethra and the membranous urethra. The anterior urethra extends from the distal external urethral sphincter to the external urinary meatus and is divided into the bulbar (inside the scrotum), penile (inside the penis) and the navicularis urethra (inside the penis glans).

Historically, infection urethritis was the leading cause of urethral strictures. But currently in the developed world, most urethral strictures are iatrogenic or idiopathic, 35-40%, with infection urethritis causing the minority of stricture. Known traumas, e.g. straddle injury in cycling, sports and work, pelvic fracture-related urethral injury such as in motor vehicle accidents, and iatrogenic injury secondary to instrumentation of urethra such as catheterization all mount to 15-20%.

What it seems to be missing and a mystery for patients and physicians, particularly urologist and is currently considered iatrogenic or unknown cause of urethral stricture that is the most common cause, is trauma to urethra during sexual activities. Any intense sexual activities that put extraneous pressure over penis and scrotum, could cause strictures in the urethra. That is why the majority of urethral strictures occur in the anterior urethra, inside the scrotum and penis. These extraneous sexual activities are repeated traumas to the urethra over time, without the knowledge of the person and that is why most of the strictures are quite long, more than 4 cm and on different spots than one. The repeated traumas to the urethra that occurs over time, takes time to show itself and cause symptoms so it is more common in middle age and older men. Unfortunately the medicine has neglected upon this common cause of trauma during sexual activities so to research on, but in the near future, the research needs to clarify this in detail and identify such trauma to a variety of sexual behaviours and acts, e.g. the frequency and risky sexual positions.

Frequent sexual activities specially during older age, when the urethra as an aged tissue is more vulnerable to trauma could be a risk factor causing urethral stricture. Some sexual activity positions such as the sexual partner on top could theoretically thrust more trauma to the penis, scrotum and consequently the urethra to cause stricture. The heavier the partner on top and the older the patient could cause more such trauma and urethral stricture. Regrettably, while the public freely discuss their sexual behaviours in media and social network, even graphically, the medicine and the physicians shy away to detail such information from their patients. But the medicine in the 21^st century needs to approach this matter more seriously in clinics and research and guide the public at large about the consequences and risk factors of some sexual behaviours, including sex positions in causing diseases, such as urethral stricture!      

References:  

1. Santucci RA, Joyce GF, Wise M. Male urethral stricture disease. J Urol 2007;177:1667-74.
2. Palminteri E, Berdondini E, Verze P, et al. Contemporary urethral stricture characteristics in the developed world. Urology 2013;81:191-6.
3. Stein DM, Thum DJ, Barbagli G, et al. A geographic analysis of male urethral stricture aetiology and location. BJU Int 2013;112:830-4.
4. Fenton AS, Morey AF, Aviles R, et al. Anterior urethral strictures: etiology and characteristics. Urology 2005;65:1055-8.
5. Lumen N, Hoebeke P, Willemsen P, et al. Etiology of urethral stricture disease in the 21st century. J Urol 2009;182:983-7.