What is the role of urodynamics in a pregnant patient?

From the Guidelines

Urodynamic testing in pregnant patients should generally be deferred until after delivery unless absolutely necessary for diagnosis and management of severe urinary symptoms that significantly impact quality of life. This approach prioritizes minimizing risks to the mother and fetus while ensuring that any intervention is tailored to address significant morbidity. If urodynamic testing is deemed necessary, it should be performed in the second trimester when possible, as this represents the safest period during pregnancy 1. The procedure involves the same components as in non-pregnant patients: uroflowmetry, filling cystometry, pressure-flow studies, and sometimes electromyography. Special considerations include:

• Positioning the patient in a semi-reclined position to avoid compression of the inferior vena cava
• Using lower filling rates (30-50 ml/min rather than standard 50-100 ml/min)
• Ensuring proper interpretation accounting for physiological changes of pregnancy such as increased bladder capacity and detrusor overactivity Antibiotic prophylaxis (typically nitrofurantoin 100mg or cephalexin 500mg) should be administered before the procedure to prevent urinary tract infections, which pose additional risks during pregnancy 1. The procedure should be performed by experienced clinicians familiar with pregnancy-related anatomical and physiological changes, and the benefits must clearly outweigh the potential risks of infection, discomfort, and theoretical risks of preterm labor. Non-invasive alternatives like bladder diaries, symptom questionnaires, and ultrasound assessments, as supported by recent studies 1, should be exhausted first whenever possible to minimize invasive procedures. Ultrasound, in particular, has been shown to be highly effective in diagnosing and managing hydronephrosis in pregnant patients, with high sensitivity and specificity for predicting the need for intervention 1.

From the Research

Urodynamics in Pregnant Patients

• Urodynamics is the study of the hydrodynamic system of the urinary tract, which includes the bladder and urethra 2.
• In pregnant patients, urodynamics can be used to assess the mechanisms underlying lower urinary tract symptoms (LUTS) or urinary incontinence (UI) 3.
• A study published in 2000 found that pregnancy and delivery did not have a consistent effect on objective bladder function, as measured by urodynamic investigations 4.
• The study found that the prevalence of genuine stress incontinence and detrusor instability were 9% and 8%, respectively, antenatally, and 5% and 7%, respectively, postpartum 4.
• Urodynamic testing can be used to assess the effectiveness of surgical treatment for pelvic organ prolapse (POP) and to identify any changes in urinary symptoms after surgery 5.
• The indications for urodynamic testing in pregnant patients are not clearly defined, but it may be helpful in certain situations, such as prior to incontinence surgery or in cases of disordered bladder emptying 6.

Urodynamic Testing

• Urodynamic testing typically involves the measurement of bladder and sphincter pressures, as well as the measurement of urinary flow and bladder sensation during filling 3.
• The test may include a free uroflowmetry, a cystometry, post-void residual measurement, and a pressure-flow study 3.
• The results of urodynamic testing can be used to diagnose and treat LUTS and UI in pregnant patients 3.
• Urodynamic testing should be performed by a competent nurse to ensure the reliability, reproducibility, and interpretability of the results 3.

Pregnancy and Urodynamics

• Pregnancy can affect the urinary tract and cause LUTS and UI 4.
• Urodynamic investigations can be used to assess the effects of pregnancy on the urinary tract and to identify any changes in bladder function 4.
• The results of urodynamic testing can be used to guide treatment and management of LUTS and UI in pregnant patients 4.