Ionizing radiation exposure has potentially lifelong effects, and its use should be minimized in the pediatric population when possible. The generally accepted premise is to have strict adherence to the “as low as reasonably achievable” (ALARA) principle when performing studies [37]. The fluoroscopic component of a UDS study provides valuable insight in many procedures, as mentioned earlier. In pediatric UDS procedures, the use of fluoroscopy should be directed at answering a specific question with the minimum radiation required, in adherence with the ALARA principle. Video UDS studies have been reported with a range of radiation exposure from an average of 2 mGy (less than an average VCUG) to 10 mGy [38, 39]. Factors that increase radiation exposure during a UDS study are providers who use longer fluoroscopy times, higher body mass index, and larger bladder capacity. Overall recommendations are to use fluoroscopy when required to answer a clinical question, but attempt to minimize radiation exposure in the child.

Urodynamics (UDS) is a powerful tool that provides objective information about a patient’s particular bladder physiology but it can be rendered essentially useless by artifacts that result from fear, pain, and the patient’s inability to focus and cooperate with the testing procedure. In pediatrics, the challenge is often greater than in the adult population because children are less likely to understand the test, appreciate the reasons for obtaining it, and they are more likely to respond to fear, pain, and disinterest in ways that disrupt the study. Therefore, one must address these issues prior to, and during the test so that the diagnostic goals of UDS are achievable.

In a study of the adult female population, Ellerkman and colleagues found that the level at which patients anticipated pain with UDS was significantly greater than the actual pain that they reported experiencing during the procedure [40]. This suggests that steps can be taken prior to the visit and at the initiation of the procedure to minimize the major component of psychological trauma associated with UDS. In pediatrics, it is critical to address the fears of both the patient and the parents, as the latter are critically important in influencing how the child perceives the test and they can be very helpful in reducing anxiety [41]. Prior to ordering UDS testing, it is wise to have a clear discussion of what the diagnostic goals are and how the child will be helped by this additional information. This should be followed by a full description of the procedure itself to eliminate any fear of the unknown. Participation by the child depends considerably on his or her age and maturity level but the clinician should make every effort to explain as much of the procedure as possible in an age-appropriate manner. Patients who are familiar with intermittent catheterization are generally more accepting of the catheters used during testing but those who are not may need more explicit instructions on how the catheters work and how they will be inserted. Child-life specialists can be very helpful especially for younger children who may benefit from a demonstration of catheterization using anatomically correct dolls constructed for this purpose. In addition to face to face instruction in the clinic visit, most practitioners provide an easy to understand handout of the procedure with helpful illustrations that describe the technical details as well as the goals and possible morbidities. Many children’s hospitals have posted their UDS handouts online and these can be a good reference if one wishes to custom design a packet for use in their practice. After a discussion in the clinic and dissemination of informational materials, patients and parents should be encouraged to contact the provider for any questions or concerns that they may have regarding the study.

Despite optimal preparation of the patient and parents prior to the study, UDS is still an invasive procedure that is associated with pain, embarrassment, and loss of privacy. The procedure clinic should be structured to allow for the test to be conducted privately and include only those staff who are responsible for performance of the study. Outside traffic should be eliminated or minimized as much as possible with respect to the privacy of the patient. With regards to the test itself, pain will be diminished by selecting the smallest catheters possible. Viscous lidocaine should be introduced into the urethra 10–15 min prior to catheterization to provide lubrication and analgesia although children who catheterize regularly may be able to proceed with minimal or no wait time. Positioning of the patient in a comfortable fashion is necessary to minimize motion artifact during the study and since many of these patients have neurological co-morbidities, care must be taken to cushion pressure points that are susceptible to formation of decubitus ulcers. Most studies can be conducted effectively in either the sitting or supine position, depending on the preference of the child. Once the catheters are placed and the patient is in a comfortable position, most studies can be performed with minimal additional discomfort. Before instillation of the contrast or saline, the patient should be told that bladder fullness may be noted, and should be reported to the clinician, but significant pain is not part of the normal study. If the patient notes acute pain during the study, the inflow should be paused and the source of the pain should be identified and corrected.

The vast majority of patients can undergo UDS testing with minimal discomfort and with avoidance of artifacts that make interpretation of results difficult or even impossible. Some children, particularly those who are sensate, may simply not be able to handle the fear and pain without some form of sedation. Sweeney et al. conducted a study to identify which children would require sedation for completion of UDS and found that the most important factor was patient age between 3 and 7 years [42]. In addition to objective parameters, the ordering physician should observe how the child behaves in a non-threatening medical setting, such as a clinic visit, which may suggest how he or she may respond in the UDS suite. Also, parents may have useful information from prior studies that the child may have experienced to help decide when any particular child would best be served with a sedated procedure.

Benzodiazepines are the mainstay of sedative agents for invasive procedures because they are safe, effective, and easy to administer orally, intranasally or intravenously. Bozkurt and colleagues demonstrated that a 0.5 mg/kg dose of midazolam administered intranasally allowed all of their patients to successfully complete meaningful urodynamic studies [43]. They also showed that a single dose of medication did not alter the urodynamic parameters observed, including the maximum cystometric capacity, contractility, compliance, intravesical pressure, maximum flow rate, detrusor pressure at maximum flow, and post-void residual. A recent investigation by Theravaja compared the relative efficacy of midazolam versus ketamine when each was given IV as a loading dose followed by a continuous infusion during the procedure [44]. They found that both agents were equally effective in providing adequate sedation but the ketamine group showed lower reactivity to placement of rectal and urethral catheters. By comparison to historical patient data, they showed that neither agent impacted any of the urodynamic parameters measured. No specific agent has demonstrated clear superiority in the setting of pediatric UDS and so the choice of agent can be made on the basis of physician preference in deference to the setting in which these drugs are used.

With the administration of any sedative, patient safety is a primary concern and institutional guidelines regarding monitoring, equipment, nursing and specialist involvement should be devised and strictly followed. Providing sedation requires regular observation of the patient’s blood pressure, oxygen saturation, and sedation level and this must be done by a credentialed individual who remains attentive during the entire procedure and afterwards in recovery. Since the urodynamic study itself demands the full attention of the urology staff, many institutions have created sedation teams to provide this service so that specific team members can focus on the safety and well-being of the patient while others can focus on the performance of the testing itself [42]. While the infrastructure and staffing requirements to provide sedated pediatric UDS may not be attainable in all facilities, they should be considered standard in all major children’s healthcare centers with a pediatric urology program.

Under the best of circumstances, pediatric urodynamic studies can be fraught with motion artifacts. Therefore, it is ideal to have the interpreting provider present at the time of the study so that these artifacts do not confuse the analysis of the results. A reasonable alternative would be to have an experienced physician extender (NP, PA) who performs the study carefully documenting the time and source of any activity or phenomena that occur during the test. Notation of artifacts, for example a rise in abdominal and bladder pressure as the child grasps for a toy, should be documented electronically in the official UDS record. Older equipment may not permit this, in which case the artifact and source should be handwritten on the printed copy of the raw data so that urologists consulting the record in the future can accurately interpret the results.

Pediatric urodynamic studies are most efficiently and effectively performed in a dedicated pediatric procedure center where staff is dedicated to and comfortable with caring for children. Waiting rooms should be constructed to provide a relaxing family atmosphere as the patient will often be accompanied by multiple family members including siblings. Age-appropriate furniture, décor, and toys/games can help reduce stress prior to the procedure, which makes it easier to acclimate the child and parents before going into the UDS suite. Efficient patient flow strategies minimize aggravating delays that can introduce unnecessary stressors which can manifest in difficult behavior on the part of the child.

A significant percentage of children undergoing UDS testing have neurogenic bowel and will present with large amounts of hard stool in the rectum. Since this can make rectal catheter placement difficult and also introduce instability to the readings from that channel, many providers utilize a bowel washout prior to the procedure. A study by deKort showed that children undergoing colonic irrigation did not appear to have any noticeable change in the results of their UDS studies and there is no literature to support or dissuade the use of a pre-procedural bowel regimen [45]. Nonetheless, administration of an enema the morning of, and in some cases several days preceding the study can help with cleanliness and ease of catheter insertion. Practitioners may set a standard institutional protocol for the use of enemas, suppositories and/or oral laxatives, or custom tailor the regimen to individual patients who are at risk of impacted stools.

The decision as to whether or not parents should be present for the test is controversial and there is certainly a great deal of discretion to be exercised by the provider, based on the social situation and interfamily relationships of individual patients. However, as part of an effort to provide patient and family centered care, the American Academy of Pediatrics endorses the practice of allowing parents to be present for invasive procedures [46]. While UDS testing was not specifically mentioned in the guidelines, it stands to reason that parental presence as a comfort measure is beneficial to the well-being of the patient and the integrity of the test.

Equipment requirements for pediatric UDS testing are similar to that which is necessary for adult testing with the exception of the specific parameters of the bladder and rectal catheters. The effect of catheter size with regards to urodynamic results has not been formally studied in children but has been shown to be an influential factor in men with obstructive urinary conditions [47]. A large catheter, particularly in small boys, has the potential of obstructing the bladder outlet and urethra which can lead to a decrease in measured flow rates and increase in measured leak point pressures. Therefore, the smallest catheter available, usually a 6 Fr dual lumen catheter, is optimal for measurement accuracy.

Even children who are able to tolerate catheter placement and the bladder filling can have difficulties remaining still and focused for the duration of the study and this can introduce troublesome artifacts. Age-appropriate entertainment such as blowing bubbles and visually attractive toys are often effective in calming and settling infants while videos, electronic games, or reading materials are excellent means to maintain focus in older children. A child-life specialist can be a valuable team member, providing suggestions for specific interventions and assistance during the exam by gentle interaction with the child and accompanying parent.

Once the test is complete, it is best to have the child dress and accompany the parent to a separate room or location that provides privacy and comfort so that post-procedural counseling can occur away from the distracting and often crowded space in the UDS suite. This gives both the parent and child an opportunity to settle down and better comprehend the discussion of test results with the provider. A light snack or beverage for the patient may be beneficial for the patient to understand that the invasive procedures are complete and impart a sense of safety.