First, Etiology
1、Ways and methods of foreign bodies entering the bladder
(1)Foreign bodies enter the bladder voluntarily or by others through the urethra: Entering the bladder voluntarily or by others through the urethra is the most common type of bladder foreign body. Patients insert foreign bodies into the urethra to achieve sexual pleasure as a form of masturbation, and then they enter the bladder; some insert foreign bodies into the bladder for the purpose of abortion or contraception. Foreign bodies are also inserted into the bladder through the urethra under the influence of mental illness or alcohol intoxication; and some people insert foreign bodies into others' urethras as a prank, causing them to enter the bladder.
(2)Iatrogenic bladder foreign bodies: Iatrogenic bladder foreign bodies are due to the introduction or retention of foreign bodies in the bladder during surgery or instrumental examination. During endoscopic examination or surgery, due to reasons such as poor instrument quality or operation, the instruments break and remain in the bladder. Long-term placement of a double 'J' tube during endoscopic surgery can lead to stone formation on the tube wall, making it impossible to remove the tube.
(3)Foreign bodies enter the bladder through open wounds: Open bladder injury can carry in foreign bodies such as fabric, buttons, bone fragments, etc., as sequelae of war injuries.
(4)Foreign bodies migrate into the bladder from outside the bladder: Patients have a history of firearm injury, pelvic fracture, chronic pelvic osteomyelitis, open surgical fixation of the femoral neck fracture. Foreign bodies become inflamed and adherent to the bladder wall, causing erosion and ulceration of the bladder wall, and foreign bodies enter the bladder. The intrauterine device in women also enters the bladder in this way.
(5)Foreign bodies enter the bladder from the intestines: Foreign bodies entering the bladder from the intestines are through intestinal bladder fistula. Most of the foreign bodies are undigested food or parasites, and often present with symptoms of flatulence, caused by tumors or tuberculosis as the main reasons for fistula formation.
2、The ways foreign bodies enter the urethra
(1)Placed into the bladder through the urethral orifice: This is the most common route for foreign bodies to enter the bladder and urethra.
(2)Discharged through the bladder: Some foreign bodies can be discharged from the bladder into the urethra, but are caught and cannot be expelled.
(3)Introduced through surgery or open injury: such as unabsorbed silk thread, cotton balls used for hemostasis, metallic mesh stents placed during surgery with subsequent infection, etc.
Second, Pathogenesis
Foreign bodies in the bladder and urethra can directly cause mechanical stimulation and injury to the bladder and urethra, infection of the urethra and surrounding tissues, urinary obstruction, hematuria, urine leakage, calculus, bladder fistula, or urethral fistula, and other complications. Men, due to their longer urethra and two natural bends, are more prone to have foreign bodies remain in the urethra without entering the bladder. Women have a shorter and straight urethra, and foreign bodies are more likely to enter the bladder through the urethra.