+
MODEL
Journal of Pediatric Urology (2014) xx, 1e5
Multicystic dysplastic kidney: Impact of imaging modality selection on the initial management and prognosis O.M. Sarhan*, M. Alghanbar, A. Alsulaihim, B. Alharbi, A. Alotay, Z. Nakshabandi Pediatric Urology Unit, Urology Department, Prince Sultan Military Medical City, Riyadh, Saudi Arabia Received 16 January 2014; accepted 18 March 2014
KEYWORDS Multicystic dysplastic kidney; Antenatal diagnosis; Vesicoureteric reflux; Prognosis
Abstract Objective: To evaluate the impact of imaging modalities on the evaluation and prognosis of children with multicystic dysplastic kidney (MCDK) disease. Patients and methods: A retrospective analysis of all children with MCDK diagnosed from 2004 until 2012 was performed. The study included 63 patients for whom all postnatal imaging modalities were available: renal bladder ultrasound (RBUS), dimercaptosuccinic acid scan (DMSA) and voiding cystourethrogram (VCUG). Cases with major congenital abnormalities or incomplete data were excluded. Abnormalities in the contralateral kidney and the fate of MCDK were also addressed. Results: At diagnosis, the average age was four-and-a-half months. The majority of cases were detected antenatally (87%). Postnatal RBUS and DMSA scans established the diagnosis of MCDK in 92% and 98% of patients, respectively. DMSA showed photopenic areas in the contralateral kidneys in 10% of patients; all of them had hydronephrosis and were confirmed to have vesicoureteral reflux (VUR). Contralateral VUR was detected in 16 patients; 63% of them had hydronephrosis. After a mean follow-up of three-and-a-half years, involution occurred in 62% of patients and the involution rate was inversely proportional to the initial size. Conclusions: The classical appearance of MCDK on RBUS was sufficient to establish the diagnosis in most patients. DMSA scan was more accurate in confirming the diagnosis and evaluating the contralateral kidney. Selective screening for VUR in patients with contralateral hydronephrotic kidney should be considered. ª 2014 Journal of Pediatric Urology Company. Published by Elsevier Ltd. All rights reserved.
* Corresponding author. Mansoura Urology and Nephrology Center, Prince Sultan Military Medical City, Riyadh 11159, Saudi Arabia. Tel.: +966 54777714; fax: +966 54762121. E-mail addresses: [email protected] (O.M. Sarhan), [email protected] (M. Alghanbar), [email protected] (A. Alsulaihim), [email protected] (B. Alharbi), [email protected] (A. Alotay), [email protected] (Z. Nakshabandi). http://dx.doi.org/10.1016/j.jpurol.2014.03.004 1477-5131/ª 2014 Journal of Pediatric Urology Company. Published by Elsevier Ltd. All rights reserved.
Please cite this article in press as: Sarhan OM, et al., Multicystic dysplastic kidney: Impact of imaging modality selection on the initial management and prognosis, Journal of Pediatric Urology (2014), http://dx.doi.org/10.1016/j.jpurol.2014.03.004
+
MODEL
2
Introduction Multicystic dysplastic kidney (MCDK) is the most common cause for cystic kidney disease in children and the second most common cause of abdominal mass in neonates [1]. The incidence ranges from 1 in 1000 to 4000 live births and the left side appears to be slightly more affected than the right [1e6]. Associated contralateral renal abnormalities are frequently encountered, where vesicoureteral reflux (VUR) predominates followed by ureteropelvic junction obstruction [1,5,7e9]. These anomalies may predispose to urinary tract infections (UTIs) with renal scarring leading to chronic kidney disease (CKD) during follow up [4,6,7,10]. Postnatal renal bladder ultrasound (RBUS) is usually sufficient for the diagnosis and detection of contralateral kidney abnormality. Additional imaging includes dimercaptosuccinic acid (DMSA) scan to confirm absent kidney function. Furthermore, a voiding cystourethrogram (VCUG) is performed to show associated VUR. The routine use of all these imaging modalities is currently debated [4,7]. Conservative, non-surgical management is the preferable protocol for treatment of MCDK, however, involution before adulthood is unpredictable. In patients with contralateral associated abnormalities, surgical intervention might be considered. The risk of developing hypertension, CKD and malignancy is rather low in most studies [4,6,7,10,11]. The analysis of the impact of different imaging modalities selection on the evaluation and follow up of patients with this abnormality was attempted. In addition, the probable fate of these kidneys on follow-up was explored.
Patients and methods After obtaining institutional review board approval, a retrospective review of all the medical records of patients diagnosed with MCDK in Prince Sultan Military Medical City between the years 2004 and 2012 was performed. The study included 63 patients (35 boys and 28 girls) who underwent baseline evaluation with RBUS, DMSA scan and VCUG. Nine patients who did not satisfy these inclusion criteria were excluded from the study. Table 1 shows the characteristics of these patients at presentation. Initial RBUS was performed in the first few weeks of life then, every six months for the first two years and annually thereafter. Determination of the MCDK size, contralateral kidney abnormalities and linear growth were documented. In addition, involution of the MCDK (either partial or complete) was assessed during follow up. The first DMSA scan was performed between the age of three and six months, as a baseline study, and repeated scans were performed when patients had initial scarring or had documented, recurrent febrile UTIs. A VCUG was routinely done for all patients between six and twelve weeks, in order to evaluate the presence of associated VUR. All patients had regular follow-ups through clinic visits at three, six and twelve months, with subsequent annual visits. This clinical follow up included history, physical examination, blood pressure measurement and urinalysis.
O.M. Sarhan et al. Table 1
Patient characteristics.
Character
Age (months) Mean [range] Gender Boy Girl Side Right Left Initial size on ultrasound (cm) Mean [range] Mode of presentation Antenatal hydronephrosis Urinary tract infections Renal impairment Incidental (mass)
Number
Percentage
63
%
4.6 [0e108] 35 28
55 45
31 32
49 51
5.3 [2.2e10] 55 4 2 2
87.2 6.4 3.2 3.2
Statistical analysis was carried out utilizing SPSS version 14 (SPSS Inc., Chicago, IL, USA). Kaplan Meier survival functions were compared using a log rank (Cox) test. A pvalue of less than 0.05 was considered statistically significant. Variables tested in relation to MCKD involution were patient gender, laterality and initial size on RBUS.
Results Most patients were diagnosed through antenatal screening (87%). However, febrile UTIs were also a presenting complaint (6.3%). Other forms of presentation were encountered as shown in Table 1. The RBUS was able to establish the diagnosis of MCDK in 92%, while DMSA scan was able to confirm the diagnosis in 98% of this group of patients. Contralateral renal abnormalities were detected in 48% of patients, where VUR was the predominate abnormality, followed by hydronephrosis. Table 2 lists the contralateral abnormalities. Furthermore, DMSA scan detected contralateral cortical photopenic areas in six out of 63 of these patients (9.5%); all of them had hydronephrosis and were confirmed to have VUR on postnatal screening. Three patients with these defects presented after febrile UTIs and two of them were diagnosed with CKD later on. Vesicoureteral reflux was diagnosed in 20 patients (32%), 16 of them had the reflux on the contralateral kidney. Among these patients with
Table 2
Contralateral urinary tract anomalies.
Contralateral abnormalities
No. patient
(%)
Vesicoureteral reflux Hydronephrosis Ureterocele Crossed ectopia Echogenic kidney Total
16 11 2 1 1 31
25 17 3 1.5 1.5 48
Please cite this article in press as: Sarhan OM, et al., Multicystic dysplastic kidney: Impact of imaging modality selection on the initial management and prognosis, Journal of Pediatric Urology (2014), http://dx.doi.org/10.1016/j.jpurol.2014.03.004
+
MODEL
Imaging of multicystic dysplastic kidney
3
contralateral VUR, most of them (14/16) had a lower grade of reflux (I, II, III) compared to (2/16) with a higher grade (IV, V). Four patients with VUR underwent surgical intervention because of breakthrough febrile UTIs during prophylaxis. Three had endoscopic correction and one had open uretero-vesical reimplantation. The mean follow-up period was three-and-a-half years (range one to nine years). Two patients developed CKD and one patient had hypertension (blood pressure exceeding the 95th centile). No patient with renal malignancy was reported in this study. Nephrectomy was necessitated in three patients due to pressure effect on adjacent organs. During follow-up, most kidneys involuted either partly (25%) or completely (37%). Table 3 shows the fate of these kidneys on follow-up. On univariate analysis, there were no statistically significant differences between the rate of MCDK involution in relation to gender, laterality and initial size on RBUS (above or below 5 cm) as shown in Table 4.
Discussion Unilateral MCDK is one of the most common congenital urinary tract abnormalities detected in children. At present, most cases of MCDK are identified through antenatal screening [4,5,9,12]. Routine postnatal RBUS is carried out to establish the diagnosis. Classical ultrasound features of MCDK on RBUS include: cysts of variable sizes and shape, an absent reniform appearance, and absence of centrally located cyst. However, in few instances it will be difficult to differentiate between MCDK and hydronephrosis based on the RBUS alone. The value of nuclear DMSA for confirming the diagnosis was also debated. It has been advocated that in the presence of classical RBUS appearance and a normal contralateral kidney, nuclear scan would not be necessary. In this review, the postnatal RBUS was able to establish the diagnosis in over 92% of the patients, in comparison to 98% who were confirmed by DMSA. However, in this review additional prognostic information was obtained by DMSA scan, which delineated contralateral photopenic abnormalities in patients who had hydronephrosis or vesicoureteral reflux on postnatal imaging. Fifty percent of patients with photopenic areas presented with febrile UTIs and two experienced CKD on follow-up. Aslam, 2006 reported one case of renal scarring in a patient with Grade V VUR on DMSA scan; this was out of 202 patients with MCDK [7].
Table 3
Fate of MCDKa in the study group.
Fate
Number
%
Involution Unchanged Surgically removed CKDb Hypertension Malignancy
39 21 3 2 1 0
62 33 4.8 3 1.6 0
a b
Multicystic dysplastic kidney. Chronic kidney disease.
Table 4 Univariate analysis of variables in relation to the involution rate. Variable
N Z 63
Gender Boy 35 Girl 28 Kidney laterality Right 31 Left 32 Initial kidney size on RBUSa
MODEL
Journal of Pediatric Urology (2014) xx, 1e5
Multicystic dysplastic kidney: Impact of imaging modality selection on the initial management and prognosis O.M. Sarhan*, M. Alghanbar, A. Alsulaihim, B. Alharbi, A. Alotay, Z. Nakshabandi Pediatric Urology Unit, Urology Department, Prince Sultan Military Medical City, Riyadh, Saudi Arabia Received 16 January 2014; accepted 18 March 2014
KEYWORDS Multicystic dysplastic kidney; Antenatal diagnosis; Vesicoureteric reflux; Prognosis
Abstract Objective: To evaluate the impact of imaging modalities on the evaluation and prognosis of children with multicystic dysplastic kidney (MCDK) disease. Patients and methods: A retrospective analysis of all children with MCDK diagnosed from 2004 until 2012 was performed. The study included 63 patients for whom all postnatal imaging modalities were available: renal bladder ultrasound (RBUS), dimercaptosuccinic acid scan (DMSA) and voiding cystourethrogram (VCUG). Cases with major congenital abnormalities or incomplete data were excluded. Abnormalities in the contralateral kidney and the fate of MCDK were also addressed. Results: At diagnosis, the average age was four-and-a-half months. The majority of cases were detected antenatally (87%). Postnatal RBUS and DMSA scans established the diagnosis of MCDK in 92% and 98% of patients, respectively. DMSA showed photopenic areas in the contralateral kidneys in 10% of patients; all of them had hydronephrosis and were confirmed to have vesicoureteral reflux (VUR). Contralateral VUR was detected in 16 patients; 63% of them had hydronephrosis. After a mean follow-up of three-and-a-half years, involution occurred in 62% of patients and the involution rate was inversely proportional to the initial size. Conclusions: The classical appearance of MCDK on RBUS was sufficient to establish the diagnosis in most patients. DMSA scan was more accurate in confirming the diagnosis and evaluating the contralateral kidney. Selective screening for VUR in patients with contralateral hydronephrotic kidney should be considered. ª 2014 Journal of Pediatric Urology Company. Published by Elsevier Ltd. All rights reserved.
* Corresponding author. Mansoura Urology and Nephrology Center, Prince Sultan Military Medical City, Riyadh 11159, Saudi Arabia. Tel.: +966 54777714; fax: +966 54762121. E-mail addresses: [email protected] (O.M. Sarhan), [email protected] (M. Alghanbar), [email protected] (A. Alsulaihim), [email protected] (B. Alharbi), [email protected] (A. Alotay), [email protected] (Z. Nakshabandi). http://dx.doi.org/10.1016/j.jpurol.2014.03.004 1477-5131/ª 2014 Journal of Pediatric Urology Company. Published by Elsevier Ltd. All rights reserved.
Please cite this article in press as: Sarhan OM, et al., Multicystic dysplastic kidney: Impact of imaging modality selection on the initial management and prognosis, Journal of Pediatric Urology (2014), http://dx.doi.org/10.1016/j.jpurol.2014.03.004
+
MODEL
2
Introduction Multicystic dysplastic kidney (MCDK) is the most common cause for cystic kidney disease in children and the second most common cause of abdominal mass in neonates [1]. The incidence ranges from 1 in 1000 to 4000 live births and the left side appears to be slightly more affected than the right [1e6]. Associated contralateral renal abnormalities are frequently encountered, where vesicoureteral reflux (VUR) predominates followed by ureteropelvic junction obstruction [1,5,7e9]. These anomalies may predispose to urinary tract infections (UTIs) with renal scarring leading to chronic kidney disease (CKD) during follow up [4,6,7,10]. Postnatal renal bladder ultrasound (RBUS) is usually sufficient for the diagnosis and detection of contralateral kidney abnormality. Additional imaging includes dimercaptosuccinic acid (DMSA) scan to confirm absent kidney function. Furthermore, a voiding cystourethrogram (VCUG) is performed to show associated VUR. The routine use of all these imaging modalities is currently debated [4,7]. Conservative, non-surgical management is the preferable protocol for treatment of MCDK, however, involution before adulthood is unpredictable. In patients with contralateral associated abnormalities, surgical intervention might be considered. The risk of developing hypertension, CKD and malignancy is rather low in most studies [4,6,7,10,11]. The analysis of the impact of different imaging modalities selection on the evaluation and follow up of patients with this abnormality was attempted. In addition, the probable fate of these kidneys on follow-up was explored.
Patients and methods After obtaining institutional review board approval, a retrospective review of all the medical records of patients diagnosed with MCDK in Prince Sultan Military Medical City between the years 2004 and 2012 was performed. The study included 63 patients (35 boys and 28 girls) who underwent baseline evaluation with RBUS, DMSA scan and VCUG. Nine patients who did not satisfy these inclusion criteria were excluded from the study. Table 1 shows the characteristics of these patients at presentation. Initial RBUS was performed in the first few weeks of life then, every six months for the first two years and annually thereafter. Determination of the MCDK size, contralateral kidney abnormalities and linear growth were documented. In addition, involution of the MCDK (either partial or complete) was assessed during follow up. The first DMSA scan was performed between the age of three and six months, as a baseline study, and repeated scans were performed when patients had initial scarring or had documented, recurrent febrile UTIs. A VCUG was routinely done for all patients between six and twelve weeks, in order to evaluate the presence of associated VUR. All patients had regular follow-ups through clinic visits at three, six and twelve months, with subsequent annual visits. This clinical follow up included history, physical examination, blood pressure measurement and urinalysis.
O.M. Sarhan et al. Table 1
Patient characteristics.
Character
Age (months) Mean [range] Gender Boy Girl Side Right Left Initial size on ultrasound (cm) Mean [range] Mode of presentation Antenatal hydronephrosis Urinary tract infections Renal impairment Incidental (mass)
Number
Percentage
63
%
4.6 [0e108] 35 28
55 45
31 32
49 51
5.3 [2.2e10] 55 4 2 2
87.2 6.4 3.2 3.2
Statistical analysis was carried out utilizing SPSS version 14 (SPSS Inc., Chicago, IL, USA). Kaplan Meier survival functions were compared using a log rank (Cox) test. A pvalue of less than 0.05 was considered statistically significant. Variables tested in relation to MCKD involution were patient gender, laterality and initial size on RBUS.
Results Most patients were diagnosed through antenatal screening (87%). However, febrile UTIs were also a presenting complaint (6.3%). Other forms of presentation were encountered as shown in Table 1. The RBUS was able to establish the diagnosis of MCDK in 92%, while DMSA scan was able to confirm the diagnosis in 98% of this group of patients. Contralateral renal abnormalities were detected in 48% of patients, where VUR was the predominate abnormality, followed by hydronephrosis. Table 2 lists the contralateral abnormalities. Furthermore, DMSA scan detected contralateral cortical photopenic areas in six out of 63 of these patients (9.5%); all of them had hydronephrosis and were confirmed to have VUR on postnatal screening. Three patients with these defects presented after febrile UTIs and two of them were diagnosed with CKD later on. Vesicoureteral reflux was diagnosed in 20 patients (32%), 16 of them had the reflux on the contralateral kidney. Among these patients with
Table 2
Contralateral urinary tract anomalies.
Contralateral abnormalities
No. patient
(%)
Vesicoureteral reflux Hydronephrosis Ureterocele Crossed ectopia Echogenic kidney Total
16 11 2 1 1 31
25 17 3 1.5 1.5 48
Please cite this article in press as: Sarhan OM, et al., Multicystic dysplastic kidney: Impact of imaging modality selection on the initial management and prognosis, Journal of Pediatric Urology (2014), http://dx.doi.org/10.1016/j.jpurol.2014.03.004
+
MODEL
Imaging of multicystic dysplastic kidney
3
contralateral VUR, most of them (14/16) had a lower grade of reflux (I, II, III) compared to (2/16) with a higher grade (IV, V). Four patients with VUR underwent surgical intervention because of breakthrough febrile UTIs during prophylaxis. Three had endoscopic correction and one had open uretero-vesical reimplantation. The mean follow-up period was three-and-a-half years (range one to nine years). Two patients developed CKD and one patient had hypertension (blood pressure exceeding the 95th centile). No patient with renal malignancy was reported in this study. Nephrectomy was necessitated in three patients due to pressure effect on adjacent organs. During follow-up, most kidneys involuted either partly (25%) or completely (37%). Table 3 shows the fate of these kidneys on follow-up. On univariate analysis, there were no statistically significant differences between the rate of MCDK involution in relation to gender, laterality and initial size on RBUS (above or below 5 cm) as shown in Table 4.
Discussion Unilateral MCDK is one of the most common congenital urinary tract abnormalities detected in children. At present, most cases of MCDK are identified through antenatal screening [4,5,9,12]. Routine postnatal RBUS is carried out to establish the diagnosis. Classical ultrasound features of MCDK on RBUS include: cysts of variable sizes and shape, an absent reniform appearance, and absence of centrally located cyst. However, in few instances it will be difficult to differentiate between MCDK and hydronephrosis based on the RBUS alone. The value of nuclear DMSA for confirming the diagnosis was also debated. It has been advocated that in the presence of classical RBUS appearance and a normal contralateral kidney, nuclear scan would not be necessary. In this review, the postnatal RBUS was able to establish the diagnosis in over 92% of the patients, in comparison to 98% who were confirmed by DMSA. However, in this review additional prognostic information was obtained by DMSA scan, which delineated contralateral photopenic abnormalities in patients who had hydronephrosis or vesicoureteral reflux on postnatal imaging. Fifty percent of patients with photopenic areas presented with febrile UTIs and two experienced CKD on follow-up. Aslam, 2006 reported one case of renal scarring in a patient with Grade V VUR on DMSA scan; this was out of 202 patients with MCDK [7].
Table 3
Fate of MCDKa in the study group.
Fate
Number
%
Involution Unchanged Surgically removed CKDb Hypertension Malignancy
39 21 3 2 1 0
62 33 4.8 3 1.6 0
a b
Multicystic dysplastic kidney. Chronic kidney disease.
Table 4 Univariate analysis of variables in relation to the involution rate. Variable
N Z 63
Gender Boy 35 Girl 28 Kidney laterality Right 31 Left 32 Initial kidney size on RBUSa
