**4. Urodynamic studies**

Urodynamic studies include uroflowmetry and cystometry. A well trained urogynaecology nurse specialist can perform urodynamic studies.

Clinically urodynamics are need in the following cases [12, 13].


#### **4.1 Uroflowmetry**

The test is conducted by requesting the patient to void on a commode that has urinary flow meter that measures voided volume over time. It is indicated whenever the patient history is indicative for presence of voting dysfunction especially those with recurrent UTI history and patients with over active bladder symptoms and voiding dysfunction symptoms prior starting anticholinergic medications as they can lead to urine retention as side effects. It is also important to consider uroflometry as preliminary test prior cystometry studies test in patients who have voiding dysfunction

symptoms and considered for surgery for prolapse or stress incontinence as they would be at high risk postoperatively [14].

Normal finding includes a voided volume of more than 150 ml voided over 16 seconds with maximum flow rate above 15 ml/sec with smooth bell shape curve.

#### **4.2 Cystometry**

It is a test involving placement of catheter in the bladder that measures the intravesical pressure (Pves) and catheter in the vagina or the rectum that measures (Pabd). The bladder is then with water at rate of 50–100 ml per min with an aim to reproduce the woman's symptoms and helps to obtain pathophysiological explanation. The pressure generated by the depressor muscle (Pdet) is calculated automatically by subtraction of (Pabd) from (Pves) [14, 15].

The test is conducted through two phases, the filling phase and then the voiding phase. During the filling phase the patient is asked to mention first desire to void (FDV) and also when they feel a strong desire to void when they would normally go to the toilet at that stage (SDV) and finally when they cannot hold urine anymore and that's taken as maximum cystometric capacity (MCC). Normal bladder function involve FDV at 150–200 ml, SVD at 300–600 ml, MCC at 400–700 ml of the volume infused [14, 15].

During the filling phase the patient is asked to cough regularly every 100 ml or 150 ml to identify any stress incontinence. Leakage without rising detrusor pressure is indicative for stress incontinence. The earlier the leakage is detected in the test the more severe the degree of stress incontinence. During the test patient is asked to report any feeling of urgency and that's counter checked with rising in the (Pdet). Normally during filling phase (Pdet) should not exceed 15 cm H2O. Rising of (Pdet) beyond 15 cm H2O indicates detrusor over activity [14, 15].

It is important to note patient with severe detrusor overactivity has less bladder compliance and the MCC is usually low. Those patients can also have very low FDV and SDV and the test at that stage should be done at lower infusion rate of the filing fluid [14, 15].

Filling phase monitoring can identify rising in the detrusor pressure with cough in some patients. Those patient presents with leakage in while coughing and the initial impression from the history is stress incontinence while the urodynamic diagnosis would be in fact bladder overactivity [3, 15].

Once the MCC is reached and patients point out that they cannot hold anymore without voiding otherwise she would leak, fluid infusion would be stooped and patient is moved while the catheter in place to void on a commode with built in uroflowmetry to assess any voiding dysfunction and calculate the voided volume, Maximum flow rate [14, 15].

#### **4.3 Ambulatory urodynamics**

The test is useful to consider when the conventional urodynamics fails to reproduce the patient symptoms and the results are inconclusive. Micro tip pressure transducer is used to messure the pressures and the bladder is filled naturally (mostly at rate of 1 ml/ min compared to the unphysiological filling in the conventional test at rate of 50 ml/ min. The patient carry out her normal daily activities, including those that commonly provoke symptoms. The test availability in vary in various units and that's in itself is a limiting factor for its use [12, 13].
