Urodynamic Study Analysis — Bhatt, Sharad (Male, 63 yrs, Patient #3379)

Patient Demographics

• Male, DOB 31/08/1962, age 63
• Classic demographic for BPH/LUTS evaluation

FILLING PHASE

Cystometric Data

Bladder Compliance

• Pdet compliance (linear regression): 29.1 ml/cmH₂O (Begin 2 ml → End 100 ml)
• Normal compliance (≥20 ml/cmH₂O is the accepted lower limit)
• No detrusor overactivity (DO) was detected on the trace during filling — the Pdet trace is flat and stable throughout the filling phase despite EMG spikes (cough artefacts confirmed by simultaneous Pabd rises)

Cough Test / Artefact Analysis

• Multiple cough markers recorded; Pves and Pabd spikes are synchronous, confirming good catheter placement and signal quality
• Pdet remains low with coughs, confirming no stress incontinence leak or artefactual DO

VOIDING PHASE

Key Parameters

NOMOGRAM ANALYSIS

ICS Bladder Outlet Obstruction Index (BOOI)

BOOI = 38 − 2 × 6.2 = 38 − 12.4 = 25.6

• BOOI ≥40 = Obstructed
• BOOI 20–40 = Equivocal
• BOOI ≤20 = Unobstructed

ICS Detrusor-Flow Plot

• The plot on page 3 confirms the data point falls in the Equivocal/borderline Obstructed region
• Obstructed slope: −1.67 cmH₂O/(ml/s); A/G number: 26 — consistent with equivocal obstruction

Bladder Contractility Index (BCI)

BCI = 38 + 5 × 6.2 = 38 + 31 = 69

• BCI >150 = Strong
• BCI 100–150 = Normal
• BCI <100 = Weak

Siroky Nomogram

• Average flow rate of 3 ml/s at 184 ml bladder volume plots well below the -3 SD line → severely obstructed/poor flow
• Qmax of 6 ml/s also plots in the below -3 SD range → confirms significantly abnormal voiding

Liverpool Nomogram

• Average flow rate and Qmax both plot in the lowest percentile bands — consistent with obstructed/severely impaired voiding

INTEGRATED INTERPRETATION

Primary Findings:

1. Detrusor underactivity (DU) — the dominant finding
   • BCI of 69 confirms markedly weak detrusor contractility
   • Despite generating 38 cmH₂O, the bladder cannot sustain adequate flow
   • Long hesitancy (28 s), prolonged voiding time (130 s vs 70 s flow time = significant abdominal straining period), interrupted voiding
2. Bladder outlet obstruction — equivocal
   • BOOI 25.6 = equivocal; the ICS nomogram and A/G number of 26 place this in the equivocal zone
   • Cannot confirm significant anatomical BOO (e.g., BPH obstruction) from urodynamics alone
3. Large post-void residual: 317 ml
   • Only 184/501 ml voided = bladder voiding efficiency of ~37% (severely impaired; normal >90%)
   • Indicates chronically underactive bladder with incomplete emptying
4. No detrusor overactivity detected
   • Despite early first sensation (82 ml) and urgency at 500 ml, the cystometric trace showed no phasic DO
   • Urgency without detrusor overactivity may represent sensory urgency
5. Normal bladder compliance (29.1 ml/cmH₂O)
   • No upper tract risk from compliance alone

CLINICAL DIAGNOSIS

Detrusor Underactivity (Underactive Bladder) with possible equivocal Bladder Outlet Obstruction

CLINICAL IMPLICATIONS & MANAGEMENT

Pediatric DJ Stent Size Selection

Two Dimensions to Determine: Diameter (French/Charrière) and Length (cm)

1. Diameter (Fr/Ch) — by Age/Weight

Practical rule: Use the smallest diameter that can be safely negotiated past the ureteral orifice — never force a larger stent, as ureteric trauma and orifice disruption are serious risks in small children.

• Neonatal pyeloplasty: 2.8–3 Fr DJ stents are well described; antegrade insertion intraoperatively is preferred
• Ureteroscopy in <5 years: 3–4 Fr is the range; passive ureteral dilation or mini-ureteroscopes (4.5 Fr) may be needed first
• PUJ obstruction (hydronephrosis): 3–4.7 Fr multi-length polyurethane stents are used for endoscopic stenting as an alternative/bridge to pyeloplasty

2. Length (cm) — by Age

Formula (Society of Pediatric Urology, SPU):

Stent length (cm) = Patient age (years) + 10

Modified formula for infants ≤3 years:

Stent length (cm) = (Age in years + 10) − 2

3. Quick Summary Chart

4. Important Practical Points

• Fluoroscopic/ultrasound confirmation of stent position is essential in all pediatric cases — visual inspection alone is unreliable
• Image-guided sizing: Where available, pre-op CT or ultrasound measurement of the renal pelvis to ureterovesical junction distance is the most accurate guide to stent length
• Avoid over-length stents in infants/toddlers — can coil into the urethra; avoid under-length — risk of stent migration proximally (well described in neonatal pyeloplasty)
• Material: Soft polyurethane or hydrophilic-coated stents (e.g. 3–4.7 Fr multi-length) are preferred for patient comfort
• Dwell time: Typically 4–12 weeks depending on indication (pyeloplasty: 6 weeks; stone: 4–6 weeks)
• Removal: Under GA in children; 9.5 Fr pediatric cystoscope with grasping forceps