Journal of Babylon University/Pure and Applied Sciences/ No.(2)/ Vol.(23): 2015
The Sensitivity of Renal Color Doppler Sonography In Differentiating Obstructive and Nonobstructive Urinary Calculi In Patients With Acute Renal Colic
Prospective Study
Kassim A. Hadi Taj-Aldean hasanain Ahmed Al bayati
Babylon medical university
Abstract
objective:
The purpose of this study was to determine the sensitivity of renal color Doppler sonography in differentiating obstructive and nonobstructive urinary calculi in patients with acute renal colic and to compare findings with nonenhanced helical computed tomography (CT)
PATIENTS AND METHODS
Between January 2009 and May 2012. Eighty five patients referred to the emergency department of Hilla teaching hospital with acute renal colic underwent nonenhanced CT and renal resistive index (RI) measurement with color pulsed Doppler sonography within 8 to 10 hours of the onset of the symptoms. Computed tomographic evaluation was based on the detection of urolithiasis and the presence of obstruction. The mean RI of each kidney and the difference between the mean RI of both kidneys were calculated and compared with CT findings.
RESULTS:
Tomography revealed obstruction in 43 patients and nonobstucted in 42 patients . Mean RI values for the obstructive and nonobstructive groups were 0.64 and 0.63, respectively. The differences in the mean RI for the patients with and without obstruction were statistically insignificant (P = .73). No significant relationship was found between the RI values, calculus location, and degree of obstruction..
CONCLUSION:
No significant relationship was found between the RI and obstruction, obstruction degree, or location. The use of this modality will be time-consuming and ineffective in routine practice.
The RI is not sensitive for detection of obstruction in patients with acute renal colic
Key words: Renal colic ,renal, resistive index m ,acute obstruction ,index ,urinary system , computed. Tomography.
الخلاصة
اجريت دراسة مقطعيه لخمسة وثمانين مريضا مصابين بالم الكلية الحاد يشتبه بإصابتهم بحصاة الكلية ,تم فحصهم بالسونار لتشخيص كون الحصاة بالكلية او الحالب كون هناللك انسداد بالكية او لا ثم تم فحصهم بالسونار الملون وتم أخذ حساسية السونار الملون , تم اجراء المفراس الحلزوني لجميع الحالات ,المفراس الحلزوني وجد ان هناللك 43 مريض مصابين بانسداد الكليه و42 مريض غير مصابين بانسداد الكلية،تم مقارنة الفرق باحساسية السونار الملون بين انسداد الكلية وعدم انسداد الكلية ، نستنتج من هذه الدراسه ان السونار الملون غير مفيد في فحص الم الكليه الحاد .
الكلمات المفتاحية : حصاه الكليه, شراين الكليه,الكليه , انسداد الكليه , المفراس الحلزوني
INTRODUCTION :
Sonography is the initial diagnostic tool for detecting renal disease; however, sensitivity and specificity of gray scale sonography in detecting acute ureteric obstruction is low.Urinary system dilatation seen on conventional gray scale sonography has been shown to be sensitive (≥90%) but not specific (65%–84%) in the diagnosis of renal obstruction. (Platt,1989)It has been reported that the diagnosis of obstructive uropathy may be missed by conventional sonography because pyelocaliectasis may occur late in obstructive conditions, and often the findings of sonography are normal despite severe renal dysfunction. (Mostbeck,1990)Arterial RI measurements by duplex Doppler sonography have been advocated for the diagnosis of obstruction. Doppler sonography enables detection of subtle intrarenal blood flow changes associated with various pathophysiologic conditions. It is useful to assess renal blood flow by Doppler sonography together with real-time sonographic information of the collecting system. (Kain,1991)
Renal colic is a common cause of severe acute abdominal pain in clinical practice. Classical symptoms include acute frank pain radiating to the groin, nausea and vomiting. There is often laboratory evidence of haematuria. Men are more often affected than women and the incidence increases with age. Acute renal colic is usually due to renal or ureteric stones. Most stones measuring 5mm or less in size will pass spontaneously. In the absence of fever and suspected pyonephrosis, patients are treated expectantly with analgesics and intravenous fluids. advances in ureteroscopy and lithotripsy offer effective, minimally invasive options for those with larger stones that fail to pass spontaneously.calculous disease tends to be recurrent and imaging evaluation is recommended at initial presentation. Imaging confirms the presence of stone, its size and location as well as the effect on renal function.( Williams ,1991- Smith ,1994)
Noncontrast helical CT is a very sensitive and specific investigation for evaluation of acute flank pain due to urolithiasis, besides helping in the detection of nonrenal causes of pain. (Feroze ,2007 )
Aim of study:
The aim of this study:
1-was to determine whether the intrarenal resistive index (RI) can be used for the diagnosis of obstruction and non obstructive due to urinary calculi in patients with acute renal colic.
2- for patients with acute renal colic is to confirm the diagnosis, define the stone size and location, and assess collecting system dilatation and complications.
PATIENTS AND METHODS:
From January 2009 to May 2012, eighty five consecutive patients suspected at clinical evaluation of having renal colic underwent cross sectional evaluations, which included Ultrasound of the abdomen. All patients were selected by the senior surgeon in the emergency department of Hilla teaching hospital, ureteric obstruction was diagnosed in the first three of the differential diagnoses. Ultrasound are part of the routine assessment in patients with abdominal pain at our institution at our hospital in addition to laboratory investigation .
Eighty five patients referred to our emergency department with acute renal colic were included in this study. Patients who had solitary kidneys, or known associated renal disease, including chronic renal stone colic, and patients who had taken nonsteroidal analgesics within 24 hours, for any reason, were excluded from the study.
In this prospective study, 85patients (40 men and 45 women) with acute renal colic and urolithiasis (age range, 10–720years; mean age 30-40 were assessed.
After initial clinical examination, all patients were evaluated with a nonenhanced spiral CT scanner (Philips Medical Systems, Best, ) a 64-channel multidetector CT scanner within 1 to 48 hours of the onset of the symptoms. The CT examination was performed without any oral or intravenous contrast material. All patients were scanned from the beginning of the adrenal glands down to the symphysis pubis with a 3-mm slice thickness and no gap. Scans were acquired at 120 kV and 60 mA. Subsequently, both kidneys of each patient who had stones anywhere within the urinary tract were evaluated with color and pulsed Doppler sonography (Sonoline Elegra Advanced scanner; Siemens). Each patient was examined during a painless period because it was not possible to perform Doppler sonography during renal colic properly. A 3.5- or 5-MHz transducer was used according to the age and size of the patient. Resistive index measurements from the interlobar arteries at the upper, middle, and lower thirds of each kidney were performed manually by a two radiologist who was blinded to the findings on the CT scans. The Doppler waveforms were made on the lowest pulse repetition frequency possible without an aliasing artifact. This maximized the size of the Doppler spectrum and decreased the percentage error in measurements. In addition, the lowest possible filter for the sonographic scanner was used. The RI ([peak systolic frequency shift – end-diastolic frequency shift peak systolic frequency shift) was calculated by means of manual measurements with the calipers. The RI for each kidney was calculated as an average value obtained from 3 to 5 waveforms in 3 different (upper, lower, and middle segments) regions of the kidney. Examination with duplex Doppler sonography required 10 to 15 minutes for each patient. Both renal stone protocol CT and pulsed Doppler sonography of the kidneys were performed within 8 to 10 hours after the beginning of clinical symptoms, depending on the patient’s history.
Computed tomographic evaluation criteria were as follows: (Platt ,1989) detection of calcification within the urinary tract and its description according to size, number, and location; (Mostbeck ,1990) assessment of the collecting system and ureteral dilatation (hydronephrosis, hydroureteronephrosis, or both); (Mostbeck ,1991) asymmetric inflammatory change of the perinephric or periureteral fat (stranding); and ( Mutgi , 1991) presence of nephromegaly. The locations of urinary calculi were classified as renal, ureter pelvic junction, proximal ureter (portion extending to the pelvic brim), mid ureter (portion overlying pelvic bone), distal ureter (portion distal to the pelvic bone), and ureterovesical junction. The size of each stone (in millimeters) as the greatest dimension was measured within the axial plane of the CT section. We defined ureteral dilatation as present when the ureter was asymmetrically dilated compared with the normal side.
Two experienced radiologists 5 years of experience assessed the degree of perinephric or periureteral stranding, nephromegaly, and collecting system dilatation subjectively by comparing the 2 sides as minimal, moderate, and marked in consensus and accordance with prior publications.( Katz , 1996- Varanelli ,2001). Cases with bilateral obstruction was excluded. Consecutively, 2 major groups were established as obstructive and nonobstructive urolithiasis.
The mean RI of each kidney and the difference between the mean RI of both kidneys (mean RI of the kidney with calculus – mean RI of the normal kidney) were calculated for all patients. The RI values were compared with CT findings. Relationships between RI values, urinary calculi location, and the existence and degree of obstruction were evaluated..
RESULTS:
Eighty five patients (40 men and 45 women) table (1)with acute renal colic and urolithiasis (age range, 10–70 years; mean age 30- 40 years, table ( 2)show age of patients .
Two major groups were established as obstructive (43) and nonobstructive ( 42) urolithiasis table (3).
In the obstructive urolithiasis group (43) ,the distribution of urolithiasis according to location was as follows: renal, n = 17(39.5%); ureteropelvic junction, n = 5(11.5%); proximal ureter, n = 4(9.5%); mid ureter, n = 5(11.5%); and distal ureter, n = 12 (28%).table (4) show location of stones.
Forty -two patients had only 1 stone, and 43 had more than 1 stone. The mean stone size was 5.5± 6.5 mm. Locations of calculi were renal, ureteropelvic, midureteral, distal ureteral.
Obstruction due to urinary calculus was determined by whether various degrees of asymmetric urinary system dilatation extended to the level of the obstructing calculus. Nonenhanced CT revealed the degree of obstruction as minimal (mild hydronephrosis and linear stranding of the perinephric fat; Figure 3A), moderate (moderate hydronephrosis with discrete perinephric fluid collection; Figure 3B), and marked (distinct hydronephrosis with thickening of the renal fascia manifesting as fluid along the renal fascia) in 19, 19, and 4 patients, table (5).Computed tomography revealed obstruction in 43 patients. Mean RI values for the obstructive and nonobstructive groups were 0.64 and 0.63, respectively. table (6)
A total of 100 urinary calculi, ranging between 2 and 60 mm, were detected in 85 patients. Calculi were smaller than 5 mm in 41 patients and larger than 5 mm in 44.
Mean RI values of the kidney with calculus – mean RI of the normal kidney were found to be 0.01 ± 0.02 were 0.01and 0.01in the obstructive and nonobstructive groups.
The differences in the mean RI and RI for the patients with and without obstruction were statistically insignificant(P = .73).No significant relationship was found between the RI values , calculus location , and degree of obstruction.
Table 1. Distribution of renal colic in relation to sex
number / Sex40 / Male
45 / Female
Table 2: Distribution of renal colic in relation to age of patients
Number / Age9 / 10-20 years
17 / 20-30 years
21 / 30-40 years
17 / 40-50years
16 / 50-60 years
5 / 60-70
85 / total
Table 3: ultrasonogrphy finding in examinations:
number / Ultrasonography finding43 / obstructive
42 / Non obstructive
Table 4: location of stones in obstructive group
Final diagnosis no .of patient %renal 17 (39.5%)
ureteropelvic junction 5 (11.5%)
proximal ureter 4 (9.5%)
mid ureter 5 (11.5%)
distal ureter 3 12 (28%)
Total 43
Table 5:The degree of obstruction by CT scan in obstructive group .
number / degree19 / minimal
19 / Moderate
4 / Marked
43 / Total
Table 6 : mean RI of both groups
RI / group0.64 / obstructive
0.63 / Non obstructive
· Fig.1.Left-sided colic in a 27-year-old female patient. A, Gray scale sonography shows a stone (arrow) located at proximal ureter causing dilatation in the collecting system. B and C, Doppler sonography shows the RI in the obstructed side (B) when compared with the nonobstructed side (C).
· Fig. 2 .30-year-old man with acute left flank pain. Sonogram shows unobstructed right kidney and corresponding normal RI.
· Fig.3. A-Nonenhanced transverse CT image at the level of the renal hila obtained 10 hours after the onset of renal colic in a 48-year-old man. An 8-mm stone (arrow) is shown in the midcalyceal system of the right kidney, where no obstruction or perirenal stranding is seen.
B -The wall of the ureter is apparently thickened (arrowhead), and there is prominent periureteral stranding (arrows).
Discussion;
Intravenous pyelography and B-mode (gray scale) sonography have been the 2 most common radiologic modalities used in populations with acute renal colic to detect calculi and obstruction before the widespread use of non–contrast-enhanced helical CT renal stone protocols. (Cronan , 1991- Platt , 1993) B-mode sonography is not very accurate in differentiating acute or chronic dilatation of the collecting system because dilatation often occurs in nonobstructive states and may fail to occur or may occur only in late obstructive states. To get additional information, duplex Doppler sonography has been performed in this population. In the last 2 decades, previous investigators have reported somewhat conflicting results regarding the additional information from duplex renal Doppler sonography over gray scale sonography, allowing diagnosis of both acute and chronic urinary tract obstruction. Some authors (Rubin , 1989- Tublin , 1994) reported that RI elevation and differences in RI (0.08–0.1) of symptomatic and asymptomatic kidneys in acute obstruction were significant, whereas others disagreed.( Tublin , 1994- Cronan , 1995)
In this study, we found mean RI values of 0.64 and 0.63 in acutely obstructed and nonobstructed kidneys, respectively. If we take the threshold value for RI as 0.70, only 6 of the obstructive group (2 minimally, 4 moderately, and 2 markedly dilated) and 4 of the nonobstructive group had RI values greater than the cutoff value, ranging between 0.71 and 0.79. No statistically significant difference between mean RI values was obtained. The mean RI (RI of the obstructed kidney – RI of the nonobstructed kidney of the same patient) was found to be 0.01 and insignificant (P = 0.73). These results seem to be in contradiction to the ones that ( Platt et al 1993) and ( Opdenakker et al , 1998) reported but are compatible with the results of (Tublin et al , 1994) and (Roy et al , 1998 )