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 Table of Contents  
Year : 2016  |  Volume : 21  |  Issue : 1  |  Page : 40-45

Digital rectal grading of benign prostatic hyperplasia: Where does it stand today?

Department of Urology, Regional Institute of Medical Sciences, Imphal, Manipur, India

Date of Web Publication4-Mar-2016

Correspondence Address:
Bijit Lodh
Department of Urology, Regional Institute of Medical Sciences, Lamphelpat, Imphal - 795 004, Manipur
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0971-9903.178104

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Background: Despite the fact that digital rectal examination (DRE) is an integral part of medical teaching curriculum, there is lack of standardized grading system for benign prostatic hyperplasia (BPH) that can be followed uniformly. Aims: To evaluate the validity of digital rectal grading for the assessment of prostate volume, in view to improve its reproducibility. Materials and Methods: This study was carried out in 150 eligible patients of BPH. Based on DRE the prostate enlargement was stratified into four grades. The degree of agreement between the expected prostate volume and measured prostate volume against each digital rectal grade were analyzed using Scatter plots. Data were analyzed using the Statistical Package for the Social Sciences. Results: The digital rectal Grades I-IV correlates well with transrectal ultrasound measurement and roughly corresponds to a volume of 27.78 ± 2.55 ml, 40.54 ± 7.69 ml, 61.08 ± 11.90 ml and 98.42 ± 23.44 ml, respectively. The expected prostate volume in digital rectal Grade II (30-50 ml) showed an underestimation and overestimation by 4.76% and 7.94%, respectively. Similarly, Grade III (expected 50-85 ml) and IV (expected >85 ml) showed overestimation by 22.50% and 23.08% respectively. The Cronbach's coefficient showed good internal consistency (α = 0. 851). Conclusions: Our attempt for standardization of the digital rectal grading satisfactorily validated in the clinical setting. It is feasibly sufficient to provide a rough estimation of the prostate volume and to classify patients with BPH.

Keywords: Benign prostatic hyperplasia, digital rectal examination, grades, transrectal ultrasound

How to cite this article:
Lodh B, Sinam RS, Singh KA. Digital rectal grading of benign prostatic hyperplasia: Where does it stand today? . J Mahatma Gandhi Inst Med Sci 2016;21:40-5

How to cite this URL:
Lodh B, Sinam RS, Singh KA. Digital rectal grading of benign prostatic hyperplasia: Where does it stand today? . J Mahatma Gandhi Inst Med Sci [serial online] 2016 [cited 2021 Dec 6];21:40-5. Available from: https://www.jmgims.co.in/text.asp?2016/21/1/40/178104

  Introduction Top

The digital rectal examination (DRE), a useful physical tool for prostate evaluation has derived from the Latin term palpatio per anum. It was the mainstay of diagnosis prostate diseases until the 1990s, when prostate specific antigen and ultrasonography has supplemented, but not replaced DRE. This unique modality has become an integral part of the medical teaching program, because of its obviousness, limited invasiveness, and cost-effectiveness. However, it requires a scrupulous and proficient examination that is acquired with long-standing practical experiences. The potential advantages include an assessment of prostate volume and distinction between malignant and benign entities. Estimation of prostate size is of paramount importance of selecting the appropriate treatment in benign prostatic hyperplasia (BPH) patients and DRE provides a sufficiently accurate measurement in most cases. [1] Theoretically, a criterion-based grading system must be adopted for assessment of prostate volume, and there is no doubt that every medical professional have their own way to appraise prostate physically. Unfortunately, a Medline search did not reveal any standardized grading system that can be followed uniformly and there is a paucity of published literature on digital rectal grading of BPH. Our study was aimed to evaluate the validity of the DRE grading system for assessment of prostate volume.

  Materials and Methods Top

Study design

This was a prospective study, conducted at Urology Department, RIMS from February 2012 to January 2014. Ethical approval was obtained from the Research and Ethics Committee of the Institute.

Inclusion and exclusion criteria

A total of 163 patients with clinical features of BPH were initially enrolled and subjected to digital rectal as well as transrectal ultrasound (TRUS) examination of the prostate. However, finally only 150 patients who fulfilled eligibility criteria were enlisted in this study. Informed written consent was taken from all the participants. Our exclusion criteria were: Patients younger than 45 years, known or suspected prostate carcinoma on DRE/TRUS, bony abnormality that restricts proper positioning, bedridden/severe co-morbid patients, obese patients (body mass index [BMI] >30 kg/m 2 ), patients with anal fissures, Grade III intravesical prostatic protrusion (IPP >10 mm).

Data collection and statistical analysis

A single trained urologist has performed all the ultrasound scanning and an experienced examiner has physically assessed and grade the degree of prostate enlargement, and both of them were unaware of their findings. We have performed a DRE in a modified lithotomy position where the patient lies on the back with his knees and hips are flexed and abducted [Figure 1]. Imaging of the prostate gland was performed using 6.5 MHz ER4-9/10ED TRUS probe (SonoAce X6, Samsung Medison) in the left lateral decubitus position with knees and hips flexed 90°. Prostate volume was calculated using the ellipsoid formula keyed into the ultrasound machine. We are following the DRE grading system of Romero et al., [2] with our modification in a more simplified way, where each grade is based on upper limit accessibility of the prostate to the tip of the examining finger and at least on one of the following: Depth of the lateral sulcus, condition of the median sulcus/posterior surface. Usually, a Grade I BPH on DRE is appreciated as easy accessibility of the upper limit of prostate, about one finger width depth of the lateral sulcus, unnoticed/shallow median sulcus [Figure 2]a]; Grade II BPH as accessibility of the upper limit of prostate with little effort, > one but < two finger width depth of lateral sulcus, prominent median sulcus [Figure 2]b]; Grade III as accessibility of the upper limit of prostate with marked difficulty, about two finger width depth of lateral sulcus, obliteration of median sulcus with rounded posterior surface [Figure 2]c]; Grade IV as inability to access the upper limit even with effort, deep depth lateral sulcus (> two finger width), obliteration of median sulcus with rounded posterior surface [Figure 2]d]. The hypothesis of this study was to determine the uniformity of the DRE grading with respect to an existing ultrasound grading. For this, we have performed an extensive literature search using the Medline/PubMed database and Google books, that revealed a four grades ultrasound classification of BPH where Grade I BPH is <30 g, Grade II 30-50 g, Grade III 50-85 g and Grade IV is >85 g. [3],[4] As the prostate tissue density is approximately 1.0, thus 1 g is equal to the volume of 1 ml. [5] In this study, we have considered the above grading system for the purpose of correlation and hence assumed similar values for the respective digital rectal grades of BPH. Scatter plots were used to verify the degree of agreement between the expected prostate volume and measured prostate volume against each DRE grade of BPH. Cronbach's coefficient alpha was measured to evaluate the reliability of this grading tool. All statistical analyses were performed using the Statistical Package for the Social Sciences (SPSS 16.0, SPSS Inc- 233 South Wacker Drive, 11 th Floor Chicago, IL 60606-6412) for windows.
Figure 1: Modified lithotomy position with knees and hips flexed and abducted

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Figure 2:

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  Results Top

Characteristics of BPH patients and their respective digital rectal versus adjusted TRUS grading for assessment of prostate volume are shown in [Table 1] and [Table 2]. In this study, the mean patient age was 67.35 ± 8.97 (46-87) and the mean prostate volume corresponds to 54.29 ± 25.87 (23.67-151.62). [Figure 3]a-d shows expected versus measured prostate volume against I-IV DRE grades of BPH. There was evidence of underestimation of prostate size by 19.05% in Grade I BPH on DRE [Figure 3]a. In patients with Grade II BPH on DRE, there were 87.30% of patients with prostate size between 30 and 50 ml and remaining 4.76% and 7.94% showed underestimation and overestimation respectively [Figure 3]b. Similarly, a digital rectal grading of III and IV showed much variation with respect to TRUS as evidenced by overestimation of 22.50% and 23.08% respectively [Figure 3]c and d]. The coefficient of internal consistency (Cronbach's alpha) was 0.851 in this study. Thus, the digital rectal grading is a reliable tool for assessment of prostate volume.
Figure 3:

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Table 1: Characteristics of patients with benign prostatic hyperplasia

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Table 2: Digital rectal versus transrectal ultrasound grading or the assessment of prostate volume

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  Discussion Top

Digital rectal examination as a diagnostic tool stands far away from its simplicity. The same holds true for its grading of BPH. However, due to empirical knowledge and lack of standardization, it possesses a significant barrier to enhance clinical skills. Here, to assess reproducibility we have followed grading of Romero et al., [2] with our modification to correlate with the existing four grade TRUS classification of BPH documented by Aguirre et al., [3] We considered a modification because of the intricate nature of the original classification and also as prostate grows it tends to assume different shapes and configurations thereby unlikely to have all the appreciable findings against each DRE grade. There is only limited knowledge exists regarding the technique of teaching and assessing DRE. Furthermore, the availability of virtual reality and rectal teaching associates are limited by cost constraints and cultural restrictions. [6],[7],[8] Barnes et al., [9] in 1959 reported grading of BPH based on the degree of its encroachment into the rectum. According to them 1-2 cm encroachment into the rectum is Grade I, >2 but <3 cm encroachment is Grade II, >3 but <4 cm is Grade III and >4 cm is Grade IV. This assessment was probably based on the fact that one finger width is roughly equivalent to 1.5 cm. [10] Recently, Tsui et al., [11] documented rating of the DRE procedure based on the width of the posterior surface area using a three-setting scale, where scale 0 is < two widths of the finger, 1 is ≥ two but < three widths of the finger, and 2 is ≥ three widths of the finger. Similarly, Reis et al., [12] in their study developed a fingertip graphical schema where for each fingertip of prostate surface area on DRE, the examiner was guided to consider 10 cubic centimeters (cc) of prostate volume. Thus for five fingertip impression on the posterior surface area a prostate volume of 50 cc was considered. In our study patients with BMI >30 kg/m 2 and Grade III IPP was excluded. The reason was complete palpation of the prostate gland is usually not possible in obese patients, and an exaggerated flexion of knees/hips is a prerequisite in the majority of the cases. [13] Moreover, findings on rectal examination vary depending on which lobes of the prostate are involved. In the presence of IPP or median lobe enlargement, the prostate assessment through DRE may be normal. [14] We have performed DRE in a modified lithotomy position and TRUS in the left lateral decubitus position. In Brazil, patients are usually examined in the modified lithotomy position whereas standing-up position is preferred in the United States and left the lateral position in the United Kingdom. [15],[16] Furlan et al., [17] in their study reported modified lithotomy as a preferred position for DRE. The left lateral position with knees and hips flexed 90° is preferred for TRUS, particularly with the end firing probe as imaging of the apex is easier and more comfortable. [18],[19] During years of clinical experience and empirical observation, it was found that DRE only assesses the posterior surface area of a three-dimensional structure. [14],[20] Roehrborn et al., [21] in their study although found a significant correlation between DRE and TRUS for assessment of prostate volume, but also noticed crude estimation and poor prediction on of the actual size. Probably patient's morphometric variables, as well as the length of the examiner's index finger, play an important role on the accuracy of the DRE. [22] Although TRUS undoubtedly correlates more accurately with the final prostate weight, but both DRE and TRUS are routinely used to estimate prostate size in the work-up of a patient with the prostate disease. [23] Thus, it is necessary to have a digital rectal grading system that can provide a rough estimation of the gland assessed. In our study, the mean prostate size corresponds to a volume of 27.78 ± 2.55 ml, 40.54 ± 7.69 ml, 61.08 ± 11.90 ml and 98.42 ± 23.44 ml for Grades I-IV, respectively. Using the three rating scale Tsui et al., [11] observed a volume of 40.08 ± 12.15, 51.75 ± 21.60 and 67.92 ± 22.79 for scale 0-2 respectively. Romero et al., [2] documented a volume of 20 g for Grade I, 30 g for Grade I/II, 40 g for Grade II, 50 g for Grade II/III, 60 g for Grade III and 80 g or greater for Grade IV in their study. DRE is still an important part of undergraduate and postgraduate medical curricula and currently mannequin-based simulators developed to use as a reaching tool and to quantify inter-examiner variability. [24]

  Conclusions Top

Despite the fact that DRE may under or overestimate the actual prostate size, the grading system provides a rough estimation of the exact prostate volume. The results of the present study have demonstrated sufficient evidence of validity to warrant the most extensive use and further reproducibility.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  References Top

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Romero FR, Romero AW, Brenny FT, Bark NM, Yamazaki DS, de Oliveira FC, et al. The prostate exam. Health Educ J 2012;71:239-50.  Back to cited text no. 2
Aguirre CR, Tallada MB, Mayayo TD, Perales LC, Romero JM. Comparative evaluation of prostate size by transabdominal echography, urethral profile and radiology (author's transl). J Urol (Paris) 1980;86:675-9.  Back to cited text no. 3
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Romero FR, Romero AW, Tambara Filho R, Brenny Filho T, de Oliveira Júnior FC. Patient positioning during digital rectal examination of the prostate: Preferences, tolerability, and results. Int Braz J Urol 2011;37:371-7.  Back to cited text no. 15
Kontturi M. Symptoms and patient evaluation. In: Altwein JE, editor. Benign Prostatic Hyperplasia: A Diagnosis and Treatment Primer. 1 st ed. New York: Merck & Co Inc.; 1994. p. 55-6.  Back to cited text no. 16
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  [Figure 1], [Figure 2], [Figure 3]

  [Table 1], [Table 2]

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