Neurourology and Urodynamics 26:247^253 (2007) Bladder Outlet Obstruction Index and Maximal Flow Rate During Urodynamic Study as Powerful Predictors for the Detection of Urodynamic Obstruction in Women Giovanni Luca Gravina,* Alessia Mariagrazia Costa, Piero Ronchi, Giuseppe Paradiso Galatioto, Guala' Luana, and Carlo Vicentini Department of Surgery, G Mazzini Hospital, Teramo-University of L’Aquila, L’Aquila, Italy Aims: To evaluate whether bladder outlet obstruction index (BOOI), a mathematical index of out- let resistance, in association with maximal £ow rate (Qmax) obtained during multichannel urody- namics (UDS) or detrusor pressure at maximal £ow rate (PdetQmax) could help the identi¢cation of obstruction in women. Methods: From January 2004 to February 2005, 401 women were assessed in our urodynamic unit. Of these, 133 were neurologically intact women, referred symp- toms suggestive of voiding disorders and had an abnormal non-intubated uro£ussometry (NIF) (BOO group). A normal NIF was de¢ned as a bell-shaped curve in presence of a Qmax >15 ml/ sec and a PVR <50 ml. Symptoms of voiding disorders were ascertained by interview and rated positive if they occurred more than occasionally. Thirty-seven women were enrolled as unob- structed if they presented a normal NIF and symptoms suggestive of voiding disorders less than occasionally (unobstructed group). Results: ROC curve demonstrated similar diagnostic accuracy in the diagnosis of urodynamic obstruction for Qmax obtained during UDS (AUC ¼ 0.908; P < 0.0001; CI99% ¼ 0.831 to 0.985) and BOOI (AUC ¼ 0.879; P < 0.0001; CI99% ¼ 0.794 to 0.918) and the least was seen for PdetQmax (AUC ¼ 0.706; P ¼ 0.001; CI99% ¼ 0.620 to 0.830). A Qmax obtained during UDS cut-o¡ 15 ml/sec provides speci¢city of 85.9% and sensitivity of 78.9%. A BOOI cut-o¡ 8 provides a sensitivity of 80.8% and speci¢city of 86.1%. The weakest sensitivity (64.2%) and speci¢city (64.6%) was recorded for PdetQmax 28 cmH 2 O. Conclusions: BOOI and Qmax obtained during UDS appears to be the most discriminating urodynamic parameters of female BOO. The use of these cuto¡ might facilitate the identi¢cation of women with functional and anatomical obstruction. Neurourol. Urodynam. 26:247 ^253, 2007. ß 2007 Wiley-Liss, Inc. Key words: voidingdisorders; anatomical; functionalobstruction INTRODUCTION The prevalence of bladder outlet obstruction (BOO) in women is still not well known [Nitti et al., 1999; Groutz et al., 2000a] because there are no universally accepted criteria to diagnose this condition in a female population. Currently, the urodynamic study remains the gold standard to assess the presence of BOO and it may help to de¢ne the etiology of LUTS. Groutz et al. [2000a] de¢ned urethral obstruction as a persistently low free maximal £ow rate (free Qmax) of less than 12 ml/sec combined with a detrusor pressure at maximal £ow rate (PdetQmax) greater than 20 cmH 2 O. Blaivas and Groutz [2000] developed an obstruction nomogram for women by ¢rst selecting, from a urodynamic database,women who met one of the following criteria of obstruction: (i) a free Qmax <12 ml/sec in repeated free uro£ow studies, combined with PdetQmax greater than 20 cmH 2 O in a sustained detru- sor contraction during a pressure-£ow study, (ii) obvious radiographic evidence of BOO in the presence of a sustained detrusor contraction of at least 20 cmH 2 O and poor Qmax, or (iii) inability to void with the transurethral catheter in place despite a sustained detrusor contraction of at least 20 cmH 2 O. More recently, Defreitas et al. [2004] further investigated the relationship between pressure-£ow parameters and clinically apparent BOO in women. An important ¢nding of this study was the presence of normal controls compared with a clini- cally obstructed group. In this study, the optimal cut-o¡ values for diagnosing BOO were a Qmax obtained during multi- channel urodynamics (UDS) less than 12 ml/sec and PdetQ- max greater than 25 cmH 2 O. Obstruction is characterized by a decreased £ow rate and a high detrusor pressure which in turn is due to an increased outlet resistance. Lim and Abrams [1995] described the use of a mathematical index [bladder out- let obstruction index (BOOI)] for aid the diagnosis of benign No con£ict of interest reported by the author(s). Giovanni Luca Gravina and Alessia Mariagrazia Costa contributed equally to this article. *Correspondence to: Giovanni Luca Gravina, Department of Surgery, Uni- versity of L’Aquila, Medical School ViaVetoio, Coppito-11/A, 67100 L’Aquila, Italy. E-mail: GIOVANNILUCA.GRAVINA@poste.it Received 15 August 2006; Accepted 28 September 2006 Published online 11 January 2007 inWiley InterScience (www.interscience.wiley.com) DOI 10.1002/nau.20375 ß 2007Wiley-Liss,Inc.