When Your Bladder Can’t Take the Pressure

I have this snuggly, cute, overweight cat that loves sleeping on me. It’s great for short periods, but she sleeps directly on my bladder. The cat’s extra weight adds pressure on my bladder, which increases my urge to pee and, predictably, makes me get up at night. This is pretty annoying (though the kitty cuddles make up for it), but at least it's only occasional. The worst, though, is that if I’m sick with a cough or sneeze, I have to kick the cat off the bed at night because it’ll make me pee my pajamas. 

Kids pee their pants, and that’s perfectly normal until they are potty trained. But when urine leaks involuntarily in adulthood, it is classified as a disease.^[1] The proper term is urinary incontinence, and it affects somewhere around 3 in 10 adults in the US.^[1] Urinary incontinence is much more frequent in women, affecting tens of millions of women in the United States.^[1] The risk of disease increases with age and obesity.^[1]

Like my cat’s moods, urinary incontinence comes in many forms. Stress urinary incontinence (SUI) occurs when urine leaks with exertion, such as sneezing, coughing, or exercise.^[1] It is the most common form of urinary incontinence and may occur in women during or around pregnancy or menopause.^[1] Urge urinary incontinence (UUI) is an increased urge to urinate that is hard to ignore and leads to leakage.^[1] It’s the second main type of urinary incontinence and is often co-diagnosed with overactive bladder syndrome.^[1] Other, less common types of urinary incontinence include postural, nocturnal, coital, and functional incontinence.^[1] Finally, mixed urinary incontinence, when multiple types of urinary incontinence occur at the same time, becomes more likely after someone’s 40s.^[1]

The bladder is  hollow, muscular, squishy and expandable, usually able to hold around 1 pint of liquid.^[2] It is made of three layers: a folded, expandable mucous layer, the muscular detrusor layer, and a tough, fibrous outlet layer.^[2] Urine is stored in the bladder when an internal urethral sphincter (a ring-shaped muscular opening) is closed. When this opens, urine flows into the urethra. The external urethral sphincter is under voluntary control, allowing us to decide exactly when we pee.^[2] With urinary incontinence, the bladder, the surrounding muscles (like the pelvic floor), or the nerves to this area are disrupted.^[1,2]

For men with urinary incontinence, the disruption is usually due to an enlarged prostate or complications from prostate cancer treatments.^[1] Many women have muscle dysfunction of either the detrusor muscles of the bladder or of the pelvic floor beneath the bladder. This muscle dysfunction typically starts in pregnancy, childbirth, or menopause, which coincides with the typical time of onset.^[1] At the same time, damage to the external urethral sphincter is present in almost all women with stress urinary incontinence.^[3] As a result, the bladder and urethra are less able to prevent urine leakage.

The vet tells me my cat is obese, which might be why she squishes my bladder when she sleeps on me. Obesity plays an important role in urinary incontinence as well. Obesity can cause an increase in oxidative stress, metabolic disorders, and nerve changes, but the extra physical mass itself is a big problem.^[3,4] Obesity can damage pelvic support structures and weaken the connective tissue and muscles of the pelvic floor.^[3,4] With abdominal obesity that increases waist size, obesity increases the pressure in the abdomen that presses on the bladder, kinda like my cat does when I try to sleep.^[3,4] Obesity’s impact on urinary incontinence - especially stress urinary incontinence - is particularly problematic as it makes exercise more difficult, which can make losing weight even harder than normal.^[4]

This brings us to treatment. Urinary incontinence treatment starts with reporting it! Because the condition can be embarrassing, many people delay discussing their symptoms with their doctor or do not report them at all.  As a result, only a minority of individuals receive effective treatment.^[1] Therapies may include medications like topical estrogen to improve blood supply, B3-adrenergic agonist and anticholinergic drugs that act on the detrusor muscle, or surgeries that support the urethra and increase bladder capacity.^[1] Devices may also be inserted to support the bladder and urethra.^[1] 

For most patients, however, the first step in treating urinary incontinence is lifestyle modification.^[1] This includes monitoring and changing what you drink, and paying special attention to caffeine, alcohol, and carbonated beverages (so probably cut down on the Four Loco energy drinks).^[1] Pelvic floor muscle training can also reduce urine leakage for those with stress incontinence.^[1] For overweight and obese individuals, weight loss can be a critical step to provide relief.^[1,5,6] Studies find that losing as little as 3-5% of bodyweight is associated with some improvement, and losing around 10% can reduce weekly episodes by around 70-75%.^[1,5,6] As stated above, weight loss can be difficult when exercise options are limited, so bariatric surgery and weight loss medications may help some patients.^[1] Clinical trials are currently investigating popular medications like GLP-1s to see if these will provide lasting relief for those with urinary incontinence. Progress on this front may help give people access to more exercise options and keep the weight off - and that’d really be the cat’s meow.

Creative Director Benton Lowey-Ball, MWC, BS, BFA

References:

[1] Aoki Y, Brown HW, Brubaker L, Cornu JN, Daly JO, Cartwright R. Urinary incontinence in women. Nature reviews Disease primers. 2017 Jul 6;3(1):17042. https://doi.org/10.1038/nrdp.2017.42

[2] Marieb EN, Hoehn K. Human anatomy & physiology. [11th Edition]. [Hoboken, New Jersey]: Pearson; [2019]. p. 1003-1007

[3] Pan J, Liang E, Cai Q, Zhang D, Wang J, Feng Y, Yang X, Yang Y, Tian W, Quan C, Han R. Progress in studies on pathological changes and future treatment strategies of obesity-associated female stress urinary incontinence: a narrative review. Translational andrology and urology. 2021 Jan;10(1):494. https://tau.amegroups.org/article/view/60334/html

[4] Long T, Cheng B, Zhang K. Abdominal obesity as assessed by anthropometric measures associates with urinary incontinence in females: findings from the National Health and Nutrition Examination Survey 2005–2018. BMC women's health. 2024 Apr 2;24(1):212. https://doi.org/10.1186/s12905-024-03059-2

[5] Wing RR, Creasman JM, West DS, Richter HE, Myers D, Burgio KL, Franklin F, Gorin AA, Vittinghoff E, Macer J, Kusek JW. Improving urinary incontinence in overweight and obese women through modest weight loss. Obstetrics and gynecology. 2010 Aug;116(2 Pt 1):284. https://doi.org/10.1097/AOG.0b013e3181e8fb60

[6] Subak LL, Wing R, West DS, Franklin F, Vittinghoff E, Creasman JM, Richter HE, Myers D, Burgio KL, Gorin AA, Macer J. Weight loss to treat urinary incontinence in overweight and obese women. New England Journal of Medicine. 2009 Jan 29;360(5):481-90. https://doi.org/10.1056/NEJMoa0806375