The importance of prostatic measuring by transrectal ultrasound in surgical management of patients with clinically benign prostatic hyperplasia

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The importance of prostatic measuring by transrectal ultrasound insurgical management of patients with clinically benign

prostatic hyperplasia

Daimantas Milonas, Darius Trumbeckas, Petras Juška1

Clinic of Urology, 1Clinic of Radiology, Kaunas University of Medicine, Lithuania

Keywords: transrectal ultrasonography, transition zone, benign prostatic hyperplasia.

Summary. Objective. To study wheather transrectal ultrasound volume determination ofthe whole prostate and of the transition zone alone correlates to resected or enucleatedweight in patients operated upon with transurethral resection of the prostate and retropubicor suprapubic prostatectomy because of presumed benign prostatic hyperplasia.

Material and methods. The study comprised 120 patients with symptomatic benign pro-static hyperplasia. Ninety patients underwent transurethral resection of the prostate and 30treated using suprapubic or retropubic prostatectomy. The weights of the specimens werecorrelated with the corresponding volumes of the transition zone and of the whole prostate,respectively, measured by transrectal ultrasound using prolate ellipsoid method.

Results. The mean weight of the resected or enucleated specimens was 36.79 g. Themean whole prostate volume in all patients was 63.14 cm3. Difference between resectedweight and prostate volume was statistically significant (p= 0.0001), whereas the meantransition zone volume was 40.14 cm3 and difference with resected weight was not signifi-cant (p=0.483). Correlation coefficients between measured total prostate volume and weightof resected tissue as well as between measured transition zone volume and weight of resectedtissue were calculated and were respectively r=0.925, p< 0.001 and r=0.958, p<0.001.

Conclusions. Measurements of the transition zone of the prostate by transrectal ultra-sound are more accurate than those for the whole prostate to predict enucleated or resectedweight. The assessment of the transition zone volume may be sufficiently reliable to be usedin the clinical management of benign prostatic hyperplasia and helpful to choose modalityof the surgery.

MEDICINA (2003) Vol. 39, No.9 - http://medicina.kmu.lt

Correspondence to D. Milonas, Clinic of Urology, Kaunas University of Medicine, Eivenių 2,3007 Kaunas, Lithuania. E-mail: [email protected]

IntroductionThe clinical importance of the transition zone (TZ)

of prostate has been raised recently (1). McNeal hasbeen developed a new appreciation of prostatic anatomy,and particularly of the TZ. His pathological and mor-phological studies have proved that enlargement of thegland in case of benign prostatic hyperplasia (BPH) isdue to the enlarged TZ and in that case there is nosignificant growth of peripheral zone (2). As “adenoma”enlarges it compresses peripheral and central zones.The borderline between transition zone and outer zonesis visible during examination by transrectal ultrasound.The total prostate (TP) and TZ volumes are measuredby formula of prolate ellipsoid (3). The measured TZvolume can predict resected weight of prostatic tissues.

TZ, or “adenoma” as we call it, but not the wholeprostate is resected during transurethral resection of

the prostate (TURP) or removed during open surgery.Therefore measurement of TZ is important for choos-ing a surgical technique (from minimally invasive tillopen) as well as medical treatment (4–7). It is alsoimportant for the prediction of the duration of surgery,blood loss (8), especially for surgeons with not verybig experience.

Though generally it is accepted that there is no di-rect correlation between prostatic volume and symp-toms of BPH, TZ volume can be used as predictor ofseverity of symptoms of BPH. Terris et al reported thatin 136 men with symptomatic BPH TZ volume corre-lated well with the severity of BPH symptoms (9).Kaplan et al showed that the TZ volume correlates wellwith urodynamic parameters of bladder outlet obstruc-tion and this correlation is especially reliable when TZindex (TZ volume /TP volume) is over 0.5 (10).

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Measurement of TZ and TP volumes is valuable incase of medical treatment of BPH as well. It is estab-lished that in case of TP volume over 40 mL and TZvolume over 30 mL, treatment with finasteride is clini-cally justified and effective, because shrinking of pros-tate and regression of clinical symptoms is caused byreduction of TZ volume. In case of smaller TZ vol-ume, when TZ index is under 0.5, alpha-blockers havea good clinical effect (12).

Thus, transrectal prostatic measurement by ultra-sound is valuable in case of management of symp-tomatic BPH, especially because prostate during digi-tal rectal examination (DRE) looks bigger than evalu-ated by TRUS. When actual prostate volume is 30–39 mL, prostate on DRE looks 9–12% bigger and whenactual prostate volume is 40–49 mL, on DRE it looks17–27% bigger (13).

In the Olmsted county study such over measure-ment of prostate on DRE was established in 49–58%of all investigations (14).

Aim of this study – to investigate whethertransrectal ultrasound volume determination of thewhole prostate and of the transition zone alone corre-lates to resected or enucleated weight in patients op-erated upon with TURP and retropubic or suprapubicprostatectomy because of presumed BPH and to es-tablish role of TZ volume in case of surgical manage-ment of BPH.

Material and methodsThe study comprised 120 patients operated on for

BPH at the Clinic of Urology of Kaunas University ofMedicine Hospital in February 2002–July 2003 (per-mission for clinical trial of local Ethics Committee No.83). The diagnosis of BPH was made according an-amnestic data, symptoms and data of clinical investi-gations by DRE, TRUS, uroflowmetry (Qmax), postvoid residual measurement by transabdominal bladderultrasound. The severity of symptoms was evaluatedby patient while completing International ProstateSymptom Score (IPSS) questionnaire including issuesof quality of life (QoL). Ninety patients underwentTURP and 30 were treated using suprapubic (8 pa-tients) or retropubic (22 patients) prostatectomy. Fourpatients from TURP group were excluded from finalanalysis because of not complete TURP.

All patients underwent TRUS before surgery, per-formed with ultrasound device model Siemens SonolineSI-250 with 5-7.5 MHz rectal probe. The whole pros-tate and TZ were scanned in the transverse and sag-ittal planes with the subject in the left lateral decubitusposition. The width of the TZ was measured started

from the inner part of the capsule, height – from thebladder neck to the clear inferior limit, the length –from the inner part of the capsule to the clear limit ofthe TZ at the verumontanum (Fig. 1). Prostate mea-surements were performed by two investigators (D.M., P. J.). TP and TZ volumes were calculated usingthe formula for a prolate ellipsoid: width x length xheight x 0.52 (3). The TP and TZ volumes were com-pared with the weight of the surgical specimen. Thespecific weight of the prostate isH”1.0, i. e. the vol-ume (mL) equals the weight (g) (15).

Statistical analysis was performed using software“Statistica 5.0”. Calculation of mean, range and stan-dard deviation was performed. Mean values were com-pared between groups using Student’s t-test. Correla-tion was assessed using Pearson’s coefficient andsimple linear regression; p<0.05 was considered toindicate statistically significant differences.

ResultsIn all patients, the range of the age was 45–87

years, mean age 68.5 years (SD±7.22). In the TURPgroup the range of age was 45–84 years, mean age68.08 (SD±7.19). In the open surgery group range ofage was 57–87 years, mean age 69.6 (SD±7.32). Therewere no statistically significant differences betweengroups (p=0.32).

One hundred and sixteen patients were enrolled tothe final analysis.

In all patients, the range of TP volume, evaluatedby TRUS, was 18.25-326.73 mL, mean volume 63.14mL (SD±43.65), the range of TZ varied from 5 to275.83 mL, mean volume 4.014 mL (SD±36.81). Theweight of the surgical specimen in all patients rangedfrom 5.0 to 280.0 g, mean weight 36.79 g (SD±36.59).The difference between TP volume and the weight ofsurgical specimen was statistically significant(p=0.0001). Thus, there was no difference betweenthe weight of surgical specimen and TRUS estimatedTZ volume (p=0.483). Correlation coefficient betweenTP volume and weight of surgical specimen wasr=0.925, p<0.001 and between TZ volume and weightof surgical specimen r=0.958, p<0.001. The simpleregression line is shown on Fig. 2.

In the TURP group the weight range of surgicalspecimen was 5–66 g; mean 23.17 (SD±13.84). TPvolume ranged from 18.25 to 79.95 mL, mean 45.91mL (SD±17.38). The range of TZ volume was 5–58.6mL, mean volume 25.39 mL (SD±12.96). The differ-ence between TP volume and the weight of surgicalspecimen in TURP group was statistically significant(p=0.00001), thus there were no difference between

The importance of prostatic measuring by transrectal ultrasound in surgical management


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Fig. 1B. Length of total prostate (53 mm) and transition zone (47 mm) on TRUS sagittal plane

Fig. 1A. Height and width of total prostate (39 mm, 53 mm) and transition zone (33 mm, 44 mm)on TRUS transverse plane

Daimantas Milonas, Darius Trumbeckas, Petras Juška


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Fig. 2B. Correlation between TZ volume and weight of surgical specimen:line of linear regression

Fig. 2A. Correlation between TP volume and the weight of surgical specimen:line of linear regression

TZ volume vs weight (all surgical procedures, N-116)Weight = –1.4221 +0.95193* TZ

Correlation: r = 0.95783

TP volume vs weight (all surgical procedures, N-116)Weight = –12.11 + 0.77408* TP volume

Correlation: r = 0.92468



BP TŪRIS

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TZ volume and the weight of surgical specimen(p=0.28). Correlation coefficients between these pa-rameters are respectively r=0.77, p<0.00001 andr=0.84, p<0.00001.

In the group of open surgical procedures (n=30),the weight of surgical specimen ranged from 18 to280 g, mean weight 75.83 g (SD±51.57). TRUS esti-mated TP volume in this group ranged from 32.87 to326.73 mL, mean volume 112.5 mL (SD±57.17). TZvolume ranged from 17.07 to 275.83 mL, mean 82.42mL (SD±48.86). Statistically significant difference wasestimated between TP volume and the weight ofresected tissue (p=0.01), although there were no dif-ference between TRUS estimated TZ volume andsurgical specimen (p=0.6). Correlation coefficientsbetween TP volume and weight of surgical specimenwas r=0.893, p<0.0001 and between TZ volume andweight of specimen r=0.942, p<0.0001.

TRUS estimated TZ volume in the TURP groupexceeded the weight of surgical specimen in 51 caseand the range of difference between volume andweight was 1-20, mean of difference 6.51 mL (g).The weight of surgical specimen exceeded TRUSestimated TZ volume in 30 cases (range of difference1–25, mean 5.03 mL (g)). In 5 cases these param-eters were equal.

In the open surgery group TZ volume estimated byTRUS exceeded weight of resected specimen in 16cases (mean difference 17.8, range 5–63 mL (g)) andin remainder cases the weight of removed tissues ex-ceeded TZ volume (mean of difference 8.57, range1–23 mL (g)).

It should be noted, that the weight of surgical speci-men usually is smaller compared to TRUS predicted.The difference becomes significant when actual sizeof prostate exceeds 100 mL.

The weight of surgical specimen was 92% ofTRUS estimated TZ volume and 67.4% of TP volumein open surgery group and 91.25% and 50.46% re-spectively in TURP group.

DiscussionAlthough weak correlations have been reported

between prostate size and lower urinary tract symp-toms, prostate size remains important in choosing treat-ment modality and predicting treatment response (16).

Though DRE is very important in initial evaluationof patients with lower urinary tract symptoms and sus-pected BPH, it is a poor predictor of actual size ofprostate, compared to TRUS, computer tomography(CT) or magnetic resonance imaging (MRI) (14).TRUS investigation is non invasive and is cheaper than

CT or MRI. The greatest accuracy can be achievedby measuring prostate with 3D image, but such a mea-surement is time consuming and it is difficult to applyit in routine practice (3). Prolate ellipse formula is usu-ally used in practice with 3 diameters in transverseand sagittal planes (width x height x length x 0.52).

The accuracy of such measurement is establishedin clinical studies with radical prostatectomies, TURPand open prostatectomies for BPH (8, 17, 18). Our studyestablished, that the weight of surgical specimen wellcorrelates with TZ volume (r=0.958) and TP volume(r=0.925), but there is no difference between the weightof surgical specimen and TZ volume (p=0.483) and thedifference between weight of tissues and TP volumeevaluated by TRUS is statistically significant (p=0.0001).

It has been shown, that measurement of TP vol-ume alone is not such a good predictor of resectedweight of surgical specimen, though in case of biggerTP volume, the weight of resected specimen is biggertoo. There have been found significant differencesbetween the weight of resected prostate and volume,determined before surgery, in the clinical studies, whereonly TP volume was measured (19, 20). It is clear,that in case of BPH surgery only hypertrophic tissues,but not the whole prostate is removed. The TZ vol-ume better correlates with the weight of surgical speci-men removed during open surgical procedure, com-pared to TURP, because in case of open surgery “sur-gical capsule” is very obvious, but it is quite difficult todistinguish borderlines between zones during TURP.

Our results indicate, that the difference is minimal:correlation coefficient between TZ volume and weightof resected specimen in the open surgery group was0.942 and in the TURP group respectively 0.868. Wedid not find statistically significant difference betweenthese parameters in both groups: p=0.483 and p=0.278.The weight of surgical specimen in open surgery groupand in TURP group were respectively 92% and 91.2%of TZ volume. Our data indicate that the main volumeof obstructive TZ is removed not only during open sur-gical procedure but also during TURP. Similar resultshave been published by other authors (8, 17). Majordifference between sonographic volume and the weightof resected tissues in TURP can be explained as fol-lows: 2.08% to 36.84% of prostate tissues part of whichbelong to TZ, usually are localized outside to verumon-tanum, which is the lower border of resection duringTURP. Also it is known that prostatic tissues shrink andloose their weight due to electro coagulation duringTURP (22). The question is why the difference be-tween TZ volume and the weight of surgical specimenremoved during an open surgical procedure still exists.



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TRUS, like many of investigations, has its limitations.Intra-observer variability in the TRUS estimate of TZor whole prostate volume was assessed as the mini-mum and maximum volume. For the TZ this was –11%to 17% of the mean value estimated. For the wholeprostate the variability was significantly higher, at –21%to +30% (17). Other authors point out that large pros-tates are spherical, not ellipsoid. Therefore commonlyused formula of prolate ellipsoid is not very accuratefor large prostates (23). We have found only one sig-nificant difference between weight of surgical speci-men and TZ volume in open surgery group (differencewas 63 mL (g)). Difference between TZ volume andthe weight of resected tissue in our study varied from+17.8 to –8.57 mL in the group of open prostatectomiesand from +6.38 to –4.87 mL in TURP group (“+” isindicated when TZ volume exceeded weight of resectedspecimen). Our data indicates that there is tendency to“overweight” TZ and actually the weight of removedtissues is lesser. In case of TURP, when the volume ofTZ usually is under 60 mL, variance of TRUS mea-surement is not essential, because it is only ±5–6 mL.In case of large prostates, when open surgery is per-

formed, greater variance of TRUS measurement is notvery essential too, because it has no influence on choiceof surgical option. In our opinion, TRUS is mostly valu-able when actual TZ volume is 30–60 mL. In such casesexperience of surgeon is mostly important factor con-cerning the choice of the type of surgical procedure.

It is accepted, that prostate incision in case of TPvolume under 30 mL is more reasonable than TURP(24, 25). TP volume under 30 mL we have found in 21cases. Mean TRUS measured TZ volume in thesecases was 10.47 mL and mean weight of resected(TURP) specimen was 9.66 g. Less invasive incisionof prostate should be considered in these cases.

ConclusionsTRUS investigation is valuable in the management

of symptomatic BPH. Measurements of the transitionzone of the prostate by transrectal ultrasound are moreaccurate than those for the whole prostate to predictenucleated or resected weight. An assessment of thetransition zone volume may be sufficiently reliable to beused in the clinical management of benign prostatic hy-perplasia and helpful to choose modality of the surgery.



Transrektinės prostatos echoskopijos reikšmė chirurginiu būdu gydant simptominęgerybinę prostatos hiperplaziją

Daimantas Milonas, Darius Trumbeckas, Petras Juška1

Kauno medicinos universiteto Urologijos klinika, 1Radiologijos klinika

Raktažodžiai: transrektinė echoskopija, tranzitorinė zona, gerybinė prostatos hiperplazija.

Santrauka. Darbo tikslas. Nustatyti transrektinės echoskopijos metu išmatuotų prostatos ir tranzitorinėsprostatos zonos bendro tūrio ir operacijos (transuretrinės prostatos rezekcijos, retropubinės ar transvezikinėsprostatektomijos) metu pašalintų prostatos audinių kiekio priklausomumą bei įvertinti transrektinės echoskopijosmetu išmatuotos tranzitorinės zonos tūrio reikšmę pasirenkant gydymo taktiką.

Tyrimo metodai. Į tyrimą įtraukta 120 pacientų, dėl simptominės gerybinės prostatos hiperplazijos operuotųKauno medicinos universiteto Urologijos klinikoje. 90 pacientų atliktos transuretrinės prostatos rezekcijos, 30 –atviros operacijos. Prieš operaciją transrektinės echoskopijos metu išmatuoti prostatos ir jos tranzitorinės zonosbendras tūris (prostatos bei tranzitorinės zonos bendras tūris apskaičiuotas naudojant elipsės formulę).Transuretrinės prostatos rezekcijos bei atvirų operacijų metu pašalintų prostatos audinių masė buvo lyginama suechoskopiškai išmatuotu prostatos ir jos tranzitorinės zonos bendru tūriu.

Tyrimo rezultatai. Vidutinis pašalintų prostatos audinių svoris buvo 36,79 g (svyravo nuo 5,0 iki 280,0 g). Jisnežymiai skyrėsi nuo vidutinio tranzitorinės zonos tūrio, kuris buvo 40,14 cm3 (p=0,483), bet statistiškai reikšmingai(p=0,0001) skyrėsi nuo vidutinio bendro prostatos tūrio 63,14 cm3. Nustatyta patikimesnė koreliacija tarp pašalintųaudinių svorio ir tranzitorinės zonos tūrio (r=0,958), negu tarp pašalinto svorio ir bendro prostatos tūrio (r=0,925).

Tyrimo išvados. Prostatos tranzitorinės zonos tūrio matavimas yra informatyvesnis už visos prostatos tūriomatavimą, nes tiksliau nustatomas operacijos metu pašalintų audinių kiekis. Remiantis tranzitorinės zonosišmatavimais, galima tiksliau pasirinkti chirurginio gydymo metodą.

Correspondence to D. Milonas, Clinic of Urology, Kaunas University of Medicine, Eivenių 2,3007 Kaunas, Lithuania. E-mail: [email protected]

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References1. Zlotta AR, Schulman CC. Transition zone volume of the pros-

tate: an important parameter for prostate cancer predictionand symptomatic BPH treatment. J Med Ultrasound 1997;5:26-30.

2. McNeal JE. Regional morphology and pathology of the pros-tate. Am J Clin Pathol 1968;49:347-57.

3. Aarnik RG, de la Rosette JJMCH, Debruyne FMJ, WijkstraH. Formula-derived volume determination. Eur Urol 1996;29:399-402.

4. De la Rosette JJMCH, D’Ancona FCH, Debruyne FMJ. Cur-rent status of thermotherapy of the prostate. J Urol 1997;157:1315-21.

5. Schulman CC, Zlotta AR. Transurethral needle ablation of theprostate: a new treatment of benign prostatic hyperplasiausing interstitial low-level radiofrequency energy. Curr OpinUrol 1995;5:35-8.

6. Kurita Y, Masuda H, Suzuki K, Fujita K, Kawabe K. Transi-tion zone ratio and prostate-specific antigen density as pre-dictors of the response of benign prostatic hypertrophy toalpha blocker and anti-androgen therapy. BJU 1997;80:78-83.

7. Madersbacher S, Marberger M. Is transurethral resection ofthe prostate still justified? Br J Urol 1999;83:227-37.

8. Aus G, Bergdahl S, Hugsson J, Norlen L. Volume deter-minations of the whole prostate and of adenomas by trans-rectal ultrasound in patients with clinically benign prostatichyperplasia: correlation of resected weight, blood loss andduration of operation. Br J Urol 1994;73:659-63.

9. Terris MK, Afzal N, Kabalin JN. Correlation of transrectalultrasound measurements of prostate and transition zone sizewith symptom score, bother score, urinary flow rate, andpost-void residual volume. Urology 1998;53:462-6.

10. Kaplan SA, Te AE, Pressler LB, Olsson CA. Transition zoneindex as a method of assessing benign prostatic hyperplasia:correlation with symptoms, urine flow and detrusor pressure.J Urol 1995;154:1764-9.

11. Marks LS, Partin AW, Gormley GJ, Dorey FJ, Shery ED,Garris JB, et al. Prostate tissue composition and response tofinasteride in men with symptomatic benign prostatic hyper-plasia. J Urol 1997;157:2171-8.

12. Kurita Y, et al. Transition zone ratio and prostate-specificantigen density: the index of response of benign prostatichypertrophy to an alpha blocker. Int J Urol 1996;3:361-6.

13. Roehrborn CG. Accurate determination of prostate size viadigital rectal examination and transrectal ultrasound. Urology

Received 23 July 2003, accepted 28 August 2003



1998;519(Suppl 1):19-22.14. Roehrborn CG, Girman CJ, Rhodes T, Hanson KA, ClinsGN,

SechSM, et al. Correlation between prostate size estimatedby digital rectal examination and measured by transrectalultrasound. Urology 1997;49:548-57.

15. Watanabe H, Igari D, Tanashi Y, Harada K, Saitoh M. Meas-urements of size and weight of prostate by means of trans-rectal ultrasonotomography. Tohoku J Exp Med 1974;114:277-85.

16. Barry MJ, Cockett ATK, Holtgrewe HL, McConnell JD,Sihelnik SA,Winfield HN. Relationship of symptoms of pros-tatism to commonly used physiological and anatomical meas-ures of benign prostatic hyperplasia. J Urol 1993;150:351-8.

17. Zlotta AR, Djavan B, Damoun M, Roumeguere T, Petein M,Entezari K, et al. The importance of measuring the prostatictransition zone: an anatomical and radiological study. Br JUrol 1999;84:661-6.

18. Baltaci S, Yagci C, Aksoy H, Elhan AH, Gogus O. Determina-tion of transition zone volume by transrectal ultrasound inpatients with clinically benign prostatic hyperplasia: agree-ment with enucleated prostate adenoma weight. J Urol 2000;164:72-5.

19. Hendrix AJM, Reintjes AGM, van Helvort-van DommelenCAM, Hofmans PAEM, Debruyne FMJ. Determination ofprostatic volume by ultrasonography. Auseful procedure inpatients with prostatism? Urology 1989;33:336-9.

20. Miyazaki Y,Yamaguchi A, Hara S. The value of transrectalultrasonography in preoperative assessment for transurethralprostatectomy. J Urol 1983;129:48-50.

21. Kyriakidis A, Georgiadis M, Stiatakis I, Kyriakidis Al, Kout-selinis A. Prostatic tissue to the verumontanum and its signifi-cance for adenomatous recurrences after transurethral resec-tion of the prostate. Eur Urol 1996;29:21-5.

22. Einarsson OJ, Lyrdal F, Neihardt FO. The “shrinkage” of theprostate during transurethral resection. Br J Urol 1983; 55:38-41.

23. Lee T, et al. Prostate shape and symptom score in benignprostatic hyperplasia. Yonsei Med J 2001;42:532-8.

24. Yang Q, Abrams P, et al. Transurethral resection or incision ofthe prostate and other therapies: a survey of treatments forbenign prostatic obstruction in the UK. Br J Urol 1999;84:640-5.

25. Jahson S, Dalen M, Gustavvson G, Pedersen J. Transurethralincision versus resection of the prostate for small to mediumbenign prostatic hyperplasia. Br J Urol 1998;84:276-81.

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The importance of prostatic measuring by transrectal ultrasound in surgical management of patients with clinically benign prostatic hyperplasia