Objective analysis of storage and voiding is relevant for fundamental knowledge of lower urinary tract function and dysfunction (LUTD) or lower urinary tract physiology in women. Invasive urodynamics includes cystometry to evaluate storage function and pressure flow study (PFS) to analyse voiding. Clinical epidemiology of storage dysfunctions (e.g., detrusor overactivity, incontinence, pain in association with filling or lack of filling sensation or compliance) are widely reported, but voiding function and ranges of (ab)normalities have not been satisfactorily reported in clinical epidemiological series. Most series have concentrated on associations of (PFS) observations and parameters with symptoms or syndromes or with imaging in limited and selected cohorts. 
It is, in general, undisputed that a relatively high (detrusor) voiding pressure with a synchronously low flow rate leads to the diagnosis of (increased) bladder outflow resistance (= bladder outflow obstruction, BOO) and it is also not disputed that the diagnosis of detrusor underactivity requires the observation of a low intravesical detrusor pressure in combination with a low flow rate. A graph, with pressure on the X-axis and flow projected on the Y-axis, provides a picture of the pressure and uroflow rate ratio during the entire micturition and is an addition to the a time based graph.(1) The relationship between pressure and flow is clinically relevant; the ratio of pressure and flowrate depicts urethral resistance and the product of pressure and flow can be used to grade contraction strength. The bladder outflow obstruction index (BOOI) and the bladder contraction index (BCI) are simplifications of these principles, based on PdetQmax and Qmax. These indices are clinically relevant in men, but also applicable in women according to a much cited expert opinion.(1) Because women have an (anatomically) inherently lower urethral (outflow ) resistance than men and BOO is much less common (due to the 'absence of a prostate'), clinical epidemiology of micturition disorders, being less prevalent in women, is difficult to obtain. Detrusor underactivity is however deemed relevant and probably prevalent in women.
The knowledge about urodynamic PFS parameters, BOOI and BCI and expected value ranges of women is sparse and how these associate with PVR and decreased flow rate or with increasing age is also sparsely reported. Moreover few reports or reported parameters and PFS-analysis methods follow the paradigm of distensible –collapsible flow-controlling zone uro (hydro-) dynamics.(1)
We present an analysis of PFS studies in a wide age range of symptomatic women without relevant neurological or anatomical abnormalities, with the aim of providing value ranges of PFS parameters, associations with not catheterized flowrate and, with PVR and with aging.

Retrospectively all women (1088), tested between 2010 and 2020 for LUTD who were able to void in a representative manner  (and >100mL; <800mL: PVR <500; and without excessive staining)  during standard urodynamic testing were included in this analysis. Indication for UDI has been: SUI-s(ymptoms) 8%; OAB-s 15%; UUI-s 13%; MUI-s 42%; Voiding-s 10% and other 12% e.g., nocturnal enuresis; pre-Boari; pre-NTx were included. Patients presenting with pain or recurrent UTI were not included. PVR was measured and PFS parameters were assessed after pressure peaks and flowrate corrections. BCI and WFmax are calculated to grade detrusor voiding contraction –contractility, apart from BOOI and URA to grade bladder outflow resistance.

See table1  and figure 1

Table 1 shows parameter values and their ranges, means and standard deviations. The right hand side of the graph shows, for comparison, the parameter values in the subgroup of patients (281) that had a void% <90. 
The figures show (Fig.1) how age (A) Qmax (B) Qmean (C) and Voided volume were distributed and also the PFS parameters (E) BOOI, (F) URA (G) BCI, and (H) Wmax. Figure 2 shows how (A) Qmax (B) Qmean and (C) Voided volume are associated with age and again also the PFS parameters (E) BOOI, (F) URA (G) BCI, and (H) Wmax. Qmax and Wmax decline with age. Graph D shows pdetQmax (pressure-X-axis) and Qmax (flow-Y-axis) of all patients with patients that had a void% of <90% shown in black dots. These are predominantly in the low pressure low flowrate area. (below BCI line 100 from left (X-axis) to right (Y-axis)) the more vertical (to right side) lines indicate the ICS ‘intermediate’ outflow obstruction area. Few patients (1,4%) have outflow obstruction and 3,8% are in the intermediate area. The lower pressure border (BOOI >20) of this aria coincides with the recently published fBOOI (Solomon-Greenwell) for female outflow obstruction (2). 
Cut-offs BCI of 100 and Wmax (<10 Wm2) are sensitive to diagnose (cause of) ineffective voiding (void% <90), but also max flowrate (<15mL/s) has (significant) association with ineffective voiding.

Analysis of a large number of voidings shows ranges of parameter values ('normal values') of women with symptoms and signs of LUT dysfunction and or with voiding percentage <90. Although the ranges of all parameters are wide (especially at the 'healthy' side) and overlap is large these results are helpful to decide on parameter cut-off values in addition to clinical comparators (as was done earlier (e.g., ref. 2)) e.g, ineffective voiding. Association of PFS parameters with age shows specifically the relevance of age related decline of detrusor voiding contraction strength. Ranges of values of commonly used PFS parameters, derived from ICS standard urodynamic testing, are obtained to provide clinical epidemiological evidence as a basis to grade female voiding function and dysfunction.

Nitti VW. Pressure flow urodynamic studies: the gold standard for diagnosing bladder outlet obstruction. Rev Urol. 2005;7 Suppl 6(Suppl 6):S14-21. PMID: 16986024; PMCID: PMC1477621.
Solomon E, Yasmin H, Duffy M, Rashid T, Akinluyi E, Greenwell TJ. Developing and validating a new nomogram for diagnosing bladder outlet obstruction in women. Neurourol Urodyn. 2018 Jan;37(1):368-378. doi: 10.1002/nau.23307. Epub 2017 Jun 30. PMID: 28666055.