Stress Urinary Incontinence in Pregnant Women: A Review of Prevalence, Pathophysiology, and Treatment Authors: B. Sangsawang and N. Sangsawang

Authors: B. Sangsawang and N. Sangsawang   
 International Urogynecology Journal –23 February 2013         
 Reviewer: Jane O’Brien, PT, MSPT – 05.08.13
1. Primary Aim – To explain the pathophysiology leading to Stress UI during pregnancy and Stress UI prevalence and treatment during pregnancy.
2. Background – Stress UI
a. Involuntary loss of urine on physical exertion such as cough, sneeze or lifting
b. Most common type of UI for pregnant women.
c. Brummen: Risk factors for SUI 1 year after delivery: older maternal age and LUTS during pregnancy at week 12.  C -section has protective effect on  bothersome SUI at 1 yr post delivery
d. Affects the quality of life in physical activity, traveling, social relationships and emotional health.  QoL worsens with increasing gestational age.  Many studies indicate women with UI during pregnancy are at higher risk for postpartum UI than those without UI during pregnancy
e. Risk factors for development of SUI during pregnancy are pregnancy and delivery related factors.

3. Study Design Method – Literature Review using PRESMA guidelines (Preferred Reporting Items for Systematic Reviews and Meta – analyses) Methods – PubMed search for English language and human subjects – 1/1990 -9/2012 – 174 articles were screened:  of those 26 were included in study, 18 of UI prevalence, 8 of UI treatment during pregnancy and post natal period (see page 4 of article for full method of search and figure 1 for eligible criteria)
4. Results of Prevalence of UI during pregnancy – (See Table 1 in article on pages 8-11 for the summary of the 18 articles). 
• USA – highest report of Stress UI - (60-75%) – Australia comparable to USA( 64%)
• Increased prevalence was with increasing gestational age, 3rd Trimester, 2nd and 1st 
• Wijma:  UI increased from 30% at 28-32 wks , 35% at 36-38 wks
• SUI ranged from 18.6% to 60%, UUI from 2% to 35% and MUI from 3.8% to 13.1% increasing with gestational age.
5. A&P of LUT during pregnancy: 
• Frequency – due to uterine weight: causes pressure on bladder and Irritation– normal capacity first trimester= 410 ml (13.6 oz) –Third Trimester 272 ml (9 oz).
• Average daily excretion, output and fluid intake are higher in 2nd trimester and lowest in the 3rd.
• Uterine position plays a role – retroverted pregnant uterus causes retention – doesn’t elevate urethrovesical  junction in pelvis or elongate urethra.
6. Pathophysiology of SUI during pregnancy
 PFM weakness causes bladder neck mobility and urethral mobility,  leading to urethral sphincter incompetence – SUI occurs when pressure in bladder is greater than urethral closure pressure and there is weakness of urethral sphincter –studies of pregnant women with SUI show weaker PFM strength compared to continent pregnant women – reason for SUI in pregnancy is unclear.  Maybe due to physiological changes during pregnancy.
Trauma to PFM due to maternal weight, the uterus and the fetus
Weight gain leads to increased pressure on PFM and bladder...can result in urethral mobility. May impair blood flow to bladder and urethra.
Increased BMI: associated with UI, POP (POP increased 3% with each unit of BMI increase). Women with POP tend to have UI, and weak PFMs. Increased weight before pregnancy is risk factor for SUI.
Growing uterus/fetus relies on solely on PFM, stresses it and results in weak PFM. Continent pregnant women (18-22weeks) have higher PFM strength and endurance that incontinent pregnant women (who also have more mobility to bladder neck than continent preg. Women.) damage to pudenal nerve, lev. Ani ms, facial supports, sphincters during pregnancy or delivery reduced PFM strength and may lead to increased bladder neck and urethral mobility.
Collagen changes during pregnancy (tensile properties and number)
Both result in reduced support of PFM and cause joint laxity and ligamentous stretch. SUI seems to be due to decreased quality and quantity of collagen. Possible genetic component to SUI (1. POP may run in the family; 2. Twin study on SUI and POP: more in monozygotic than dizygotic twins)

Hormonal Changes during pregnancy
Relaxin decreases btw 17-24 weeks gestation, causing decreased urethral pressure, correlates with more SUI. Pregnant women with SUI show decreased urethral pressures and defective transmission of urethral pressures. But, decreased hormone levels during pregnancy doesn’t correlate with changes in urethral pressure measurements.
Expansion of Uterus and Fetal Weight
Side Note :  By product of larger uterus and increased fetal weight is urine leakage (Pressure on bladder, changes bladder neck position, decreased bladder capacity, Bladder pressure exceeds Urethral pressure and leads to UI – stress most common).  Also consider hormonal changes leading to decreased strength and support of sphincter incompetence – most resolve in 3 months after delivery – UI prevalence decreases with time – can be factor for 27.4 % for 6 month post partum.
 Thomas:  UI developed during pregnancy  - 8 % had resolution and 47 % still had UI after 6 months post partum.
 Glazener:  13.5 % Prim gravid (first pregnancy) – SUI after 3 months post partum.
 Wesnes:  14 % - 6 months post delivery.
 Groutz:  10.39 % had SUI 1 year after vaginal delivery.
7. Treatment:
 PFM exercise – 1ST line of treatment for SUI – Cure Rates as high as 84 % / Improvement Rates 100 %.  Best outcome is PFM exercises are those directed by midwife or educator verses simple advice. Literature shows PFME for pregnant women decreases UI severity, in frequency, volume of leakage and SUI severity score….is safe, inexpensive, effective, can do anywhere.
 Sangsawang and Serisanthien PFME for 6 wks decreased sx severity in pregnant wm w/SUI weeks
 Sampselle:  PFM exercises during pregnancy and post partum can reduce SUI at 35 weeks gestation, 6 weeks and 6 months post.
 Morkved:  32 % UI at 36 weeks vs 48 % in control group.
 Ko et al:  Late pregnancy and post partum, lower UDI-6 and IT Q-7 scores in PFM exercise group – PFM exercise in pregnancy can be effective to prevent and treat UI in pregnancy with effects lasting post partum
 Stafne:  PFM exercise during pregnancy can treat and prevent UI in late pregnancy.
 Alewinjse:  Women with more severe UI were more likely to adhere to PFM exercises than women with mild symptoms.
Long term adherence is low.
8. Conclusion:   PFM exercise is effective for SUI during pregnancy without adverse effects – can improve continence when done adequately.
Clinical Relevance: 1) Helpful info for our pregnant patients to help prevent SUI during pregnancy and postpartum period. 2) Helpful for marketing to OB/GYNs