Detrusor underactivity (DU) is a common cause of lower urinary tract symptoms (LUTS) in both men and women. DU is present in 9-48% of men and 12-45% of elder women undergoing urodynamic evaluation for non-neurogenic LUTS. The detrusor underactivity concept itself remain under debate, and there is still no consensus on terms and definition (1). The ICS definition for DU is based on two characteristics: i) A weak strength of detrusor contraction; and ii) a short duration of the detrusor contraction. Evaluation methods for the duration of detrusor contraction has not been reported so far, on the other hand, some methods for the strength of detrusor contraction has been reported such as projected isovolumetric pressure (PIP) (2) and combination of UDS parameters (3). The aim of this study was to investigate elderly female patients with DU at our hospital using two methods of PIP1 (Pdet@Qmax+Qmax) and cutoff criteria of UDS parameters.

Our accumulated urodynamic date between 1997 and 2017 was retrospectively examined. Hundred and eighty-six out of 359 female LUTS patients (more than 50-year-old) was selected from UDS data base for investigation. Many patients were excluded because of no urination in PFS and lack of UDS data. We used two methods to evaluate detrusor underactivity. One method was a PIP1 evaluation. PIP1 less than 30 was considered indicative of a detrusor underactivity. Another method of cutoff criteria is the combination of UDS parameters as follows; Pdet@Qmax<20cmH2O, Qmax<15mL/s, and BVE% < 90. This strict cutoff criteria method may discriminate between DU and BOO (bladder outlet obstruction) from patients with low urinary flow.

The age of investigated women was 66.8 ± 8.2-year-oldb(N=186). The background disease and conditions were as follows; pelvic organ prolapse 66, stress urinary incontinence 56, urgency incontinence 12, neurogenic bladder 15, and others 22. The results of evaluation with two methods were shown table 1 and table 2.  Age, Qmax, Pdet@Qmax, Qmax in PFS, and PIP1 were significantly different between DU and non-DU groups. These statistical significant different items in PIP1 evaluation were like that in cutoff criteria evaluation. Percentage of DU was 25.3%(47/186) in PIP1 and 15.6%(29/186), respectively. These DU group partially overlapped each other.

The DU percentage evaluated by cutoff criteria was lower than that by PIP1 (15.6% vs 25.3%). The reason for higher percentage of DU group in P1P1 may be inclusion of BOO patients, on the other hand, that in cutoff criteria evaluation may exclude BOO patients. Twenty of 29 DU patients in the cutoff criteria were the same DU patients in the PIP1 evaluation. This means both DU groups overlapped each other. Therefore, other uncovered reason for different percentage of DU groups might exist.

The percentages of elder LUTS women with DU were 23.5 % in PIP1 selection and 15.6% in cutoff criteria respectively. The DU patients examined by PIP1 and cutoff criteria evaluation was not identical.

Eur Urol 2014,65(2):389-398
Neurourology and Urodynamics 23:184-189, 2004
Eur Urol 69:361-369, 2016