Uterine fibroids are common, non-cancerous growths that develop within the muscular wall of the uterus. They vary significantly in size and location, though not all cause symptoms. Urinary tract infections (UTIs) are also frequent, caused by bacteria entering the urinary system. Fibroids often cause urinary issues that are easily confused with an infection, leading to questions about a potential link. This article explores the connections between uterine fibroids and the increased risk for UTIs.
Understanding Uterine Fibroids and Urinary Tract Anatomy
Uterine fibroids, also known as leiomyomas, are firm, non-cancerous tumors that grow in or on the wall of the uterus. They are classified by location: subserosal (outer surface), intramural (within the wall), and submucosal (protruding into the cavity). Fibroids can expand the uterus significantly, sometimes reaching the size of a four- or five-month pregnancy.
The link between fibroids and urinary problems stems from the close proximity of the reproductive and urinary organs in the pelvis. The uterus sits immediately behind the bladder, and the ureters pass close to the sides of the uterus. As fibroids grow, especially those on the front side, they press directly against the bladder. This anatomical relationship means uterine growth can impede the normal function of the urinary tract.
Mechanical Interference and Increased Infection Risk
Fibroids themselves do not cause a bacterial infection, but they increase the risk of developing a UTI through mechanical interference. Large fibroids, especially those positioned anteriorly, physically compress the bladder, reducing its functional capacity.
This compression often leads to a frequent and urgent need to urinate, as the bladder cannot store a normal volume. Pressure on the bladder outlet can also interfere with complete emptying. When urine remains in the bladder (urinary retention or stasis), it creates an environment favorable for bacterial growth. Bacteria entering the urethra are normally flushed out, but incomplete emptying allows them to multiply and cause an infection (cystitis).
In rare cases, large fibroids can compress the ureters, causing urine to back up toward the kidneys. This obstruction may lead to hydronephrosis or a severe kidney infection called pyelonephritis. Fibroids create the physiological conditions for recurrent UTIs, though they do not introduce bacteria.
Differentiating Urinary Symptoms
Fibroids often cause non-infectious urinary symptoms that mimic a true UTI, making accurate diagnosis challenging. Symptoms like urinary frequency (urination more than eight times daily), urgency, and nocturia (waking up at night to urinate) result from direct pressure on the bladder, not infection. In these cases, the urine is sterile, and discomfort is due to physical compression reducing bladder capacity.
Specific symptoms suggest a true bacterial infection requiring treatment. These include dysuria (pain or burning during urination), cloudy or foul-smelling urine, and sometimes hematuria (blood in the urine). A fever or pain in the back or flank may indicate the infection has progressed to the kidneys. Symptoms caused by fibroid pressure are often chronic, whereas UTI symptoms tend to be acute.
Distinguishing between pressure and infection requires medical testing. A urinalysis and urine culture are necessary to identify the presence and type of bacteria causing an infection. If the culture is negative despite urinary symptoms, imaging tests such as ultrasound or MRI are used to map the size and location of the fibroids causing the mechanical pressure.
Addressing the Root Cause: Treatment Approaches
When fibroids cause recurrent UTIs or persistent pressure symptoms, treating the infection with antibiotics provides only temporary relief. The long-term strategy involves managing or eliminating the source of the mechanical interference. Treatment selection depends on symptom severity, fibroid size and location, and the patient’s desire for future fertility.
Medication options, such as hormonal therapies, may temporarily shrink the fibroids, reducing pressure on the bladder. Minimally invasive procedures target the fibroids without major surgery. Uterine Artery Embolization (UAE) is one option, where the blood supply to the fibroids is blocked, causing them to shrink and relieve pressure on surrounding organs.
Surgical interventions include myomectomy, which removes the fibroids while preserving the uterus, and hysterectomy, the complete removal of the uterus. These procedures eliminate the physical mass causing compression, restoring normal urinary flow and lowering the risk of future UTIs. The goal of treatment is to alleviate the pressure, resolving non-infectious symptoms and removing conditions that favor bacterial growth.