Congenital anomalies of the kidney and urinary tract in Nigeria: a thirteen-year single centre review

Abstract

Background

Congenital anomalies of the kidney and urinary tract (CAKUT) encompass a wide spectrum of structural anomalies of the kidney and urinary tract. Evidence from registries in high-income countries suggests that it is a major cause of morbidity in children, with up to 50%-60% of chronic kidney disease (CKD) resulting from CAKUT. The picture is not so clear in medium and low-income countries, mainly due to lack or nonexistence of reliable registries, constraints of skilled personnel, diagnostic capacities, accurate data gathering and poor health-seeking behaviour.

Methods

Information on children managed from birth to 18 years with CAKUT, from January 2010 to end of December 2022 in the renal unit of the paediatric department, Jos University Teaching Hospital was extracted for review from the general paediatric renal database.

Results

One hundred and one children had CAKUT, representing (14.87%) of all children seen in the renal unit during the period. The prevalence of CAKUT among the general paediatric population during the same period was 0.53%. The mean age at diagnosis was 6.35 ± 5.53 years (76 months). There was male preponderance, n = 72(71.29%). The most common kidney anomaly was cystic kidney, n = 17(16.83%), while the most common urologic anomaly was pelvi ureteric junction obstruction (PUJo) n = 26 (25.74%). Recurrent fever and abdominal pain were the commonest symptoms in older children. The antenatal detection rate was very low, only nine (8.9%).

Conclusion

Pelvi ureteric junction obstruction was the commonest single anomaly. Antenatal ultrasound detection rate was very low and recurrent fever and abdominal pain were the most frequent symptoms in older children.

Introduction

The spectrum of congenital anomalies of the kidney and urinary tract (CAKUT) is wide and includes varying types of faulty structural and functional developmental differences [1]. These conditions may exist as isolated anomaly or as part of phenotypic features of a syndrome with other congenital malformations [2]. The term CAKUT, loosely applied comprises anomalies affecting the kidney, collecting system, bladder and the urethra or of position. These include abnormalities such as renal dysplasia and hypoplasia, cystic kidney disease, pelvi-ureteric junction obstruction and megaureter, ureterocoele, vesico-ureteric reflux, posterior urethral valve, and of ectopia [2–5].

In the general paediatric population, prevalence of CAKUT ranges between 3 and 26.6% while in the prenatal period, it is the commonest malformation constituting 20–30% of all congenital anomalies [5–7]. It is also estimated that CAKUT accounts for 25% of all paediatric surgical conditions [8].

In utero, the diagnosis of CAKUT can be suspected when there is oligohydramnios in the mother. Another important prenatal pointer to CAKUT is foetal hydronephrosis. After birth, other features may include urinary dribbling, recurrent urinary tract infections, abdominal swelling or intermittent abdominal pain [3, 7–9].

In settings with well structured health systems and laid out guidelines, routine prenatal ultrasound screening means that foetus with CAKUT would be easily identified as early as 18 weeks of gestation. In medium and low-income countries however, diagnosis of CAKUT is made predominantly postnatally and sometimes very late into adolescence. This is majorly because of very low prenatal screening rate, fewer skilled personnel, limited capacity for detection and diagnosis as well as poor health seeking behaviour [10, 11].

Capacity for appropriate investigations are also limited and this significantly contributes to the poor detection rate of CAKUT in many of these low-income countries like Nigeria. Basic imaging studies as ultrasonography, micturating cysto-urethrogram (MCUG) and intravenous urography (IVU) are all that many centers in this setting have access to. Some of these diagnostic tools are associated with some limitations and risks to both patients and health workers, particularly the high radiation dose. Other diagnostic tools such as nuclear imaging study like MAG3, magnetic resonance imaging (MRI) and computerized tomography (CT) scan [12] are found in few centers with costs that are almost prohibitive.

In young children, febrile urinary tract infection (UTI), especially of non- Escherichia coli, should arouse a high index of suspicion to the likelihood of CAKUT. Other features would be recurrent UTIs and those who have poor or unsatisfactory response to appropriate antibiotic treatment. In many low-income and tropical countries like Nigeria, there are other cofounding factors that blur the suspicion of UTI like malaria, which is a common cause of febrile illness in children. This may result in the initial consideration focusing on that cause of fever instead of UTI [13, 14]. This may result late diagnosis and treatment of UTI, with increased risk for renal scars and other associated late complications such as hypertension, CKD and end stage kidney disease (ESKD) [15–17].

Though there have been some studies on CAKUT in the paediatric population from Nigeria and other countries in sub-Sahara Africa. Many of these studies are constrained by their small study populations and limited knowledge of paediatric nephrology in many of these reports. Furthermore, many of these studies are retrospective folder reviews. These challenges have created gaps in the understanding of the true burden of this condition emanating from the region. This current study seeks to address some of these limitations.

Methods

This study was commenced in January 2010. The focus was to identify gaps in the scope of earlier report on kidney and urinary tract anomalies in children published previously from this centre.

The study was carried out in the Paediatric renal unit of the Jos University Teaching Hospital, Jos, a federal teaching hospital that has a 500-bed capacity. It provides services for most of the states in the north central-region of Nigeria, including the Federal Capital Territory (FCT). The unit provides specialist care for children with kidney and urinary tract diseases, including dialysis.

The bulk of the study population came from Plateau state and many who were referred from seven other neighbouring states (Benue, Nasarawa, Kaduna, Bauchi, Gombe, Taraba, Adamawa) and FCT. The data was collected prospectively using a data collection tool for each child and the information later transferred to a Microsoft excel spread sheet. The duration of data collection covered a period of thirteen years, from January 2010 and the end of December 2022. The study participants were aged from birth to 18 years.

Details of all children seen and managed for any kidney and urinary tract disease in the unit was entered into a case record form that was designed to capture relevant information. These included demographic data, presenting complaints, relevant physical examination findings, results of investigations done, final diagnosis, and the nature of care given. These data were periodically entered into an excel spread sheet subsequently until the end of the study period.

For the present study, information of all children diagnosed with CAKUT was extracted from the general renal database and retrospectively analysed.

Diagnosis of CAKUT was based on both clinical and imaging studies, which included ultrasound, radiology, magnetic resonance imaging (MRI), computerized tomography (CT), including CT urography studies. A few of the study participants with antenatal ultrasound diagnosis were referred by the Obstetricians. Only one child could have a mercapto acetyl triglycine (Tc99-MAG3) nuclear study from another center.

Ethical approval was given by the institutional research ethic committee (IREC) of the Jos University Teaching Hospital.

Analysis was done using EPI info version 7.2.6.0. The results are presented as absolute frequency and percentage for qualitative variables while quantitative variables are presented as median with minimum and maximum values or mean with standard deviation.

Results

One hundred and one (101) children were diagnosed with CAKUT during the study period. This represented a prevalence of 14.87% of the total number of 679 children with kidney and urinary tract diseases and 0.54% of the overall paediatric population of 18,920, that included all new cases either admitted to the ward or seen in the paediatric outpatient clinic. Of the 101 patients, 72 (71.29%) were males, with a male to female ratio of 2.5:1. Their mean age was 6.35 ± 5.53 years (75.54 ± 65.62 months). The median age at presentation was 60 months, interquartile range (IQR) 12–132 (Table 1).

Table 1.

Shows the distribution of the types of CAKUT diagnoses

Site of CAKUT	Diagnosis	Frequency (n)	Percentage (%)
Kidney	Cystic kidneys Hypoplastic kidneys Multi cystic dysplastic kidneys Ectopic kidneys Single kidneys Cross-fused kidneys	10 2 9 9 10 5	9.90 1.98 8.91 8.91 9.90 4.95
Urinary tract	Pelvi-ureteric junction obstruction Posterior urethral valves Congenital megaureter Uretrocoele	26 21 2 2	25.74 20.79 1.98 1.98
	Others	5	4.95
Total		101	100

(Others: Duplex system, congenital meatal stenosis, congenital neuropathic bladder, non-PUV bladder outlet obstruction)

Only 9(8.91%) of the children had antenatal ultrasound detection. There were five males and four females in this category. Postnatal confirmation showed that four of these children had posterior urethral valves, two had PUJo while three had multicystic dysplastic kidney disease (MCKD). Table 2 shows the age at diagnosis of the different anomalies and their gender distributions. Children whose anomalies were detected antenatally are included in the group under twelve months.

Table 2.

Age at diagnosis and gender distributions of children with CAKUT

Age distribution (months)		Gender
	Male n(%)	Female n(%)	Total n(%)
< 12	16(22.22)	7(24.14)	23(22.77)
12–60	22(30.56)	8(27.59)	30(29.70)
> 60–144	23(31.94)	6(20.69)	29(28.71)
> 144	11(15.28)	8(27.59)	19(18.81)
Total	72(100)	29(100)	101(100)

The distribution of the different categories of anomalies by age is shown in Table 3. For collecting system, most children presented in the first five years, 17/27 (58.62%). For kidney anomalies, most cases presented at a later age greater than five years, 30/46 (65.22%), while for lower tract anomalies, majority 21/27 (77.8%) presented early before five years. One of the common kidney anomalies was single kidney in 10 children, six had single kidney on the right while in four, it was on the left.

Table 3.

Distribution of the different types of diagnoses according to age

CAKUT types		Age categories (months)
	< 12 n(%)	12–60 n(%)	> 60–144 n(%)	> 144 n(%)	Total n(%)
Collecting system	10(37.04)	7(26.92)	9(33.33)	3(14.29)	29(28.71)
Kidney	5(18.52)	10(38.46)	13(48.15)	17(80.95)	45(44.56)
Bladder/Urethra	12(44.44)	9(34.62)	5(18.52)	1(4.76)	27(26.73)
Total	27(100)	26(100)	27(100)	21(100)	101(100)

Presentation for most of the conditions occurred beyond 12 months of life in the three categories; collecting system at 65.52%, kidney 88.89% and bladder/urethra at 55.56%. These indicate late presentation for most of the conditions (Figs 1, 2 and 3).

Fig. 1.

Intravenous urography of one of the children with the dark arrow pointing at the right sided cross-fused ectopia

Fig. 2.

3D Volume rendered image from Computerized urography in a child with left sided pelvi-ureteric junction obstruction. Note the dark arrow showing absence of drainage on the affected side

Fig. 3.

MAG3 renogram of a 3-year old girl with left PUJo and poor drainage

The coexistence of CAKUT with other renal and non-renal disease conditions were observed as well. These comorbidities are shown in Table 4.

Table 4.

Coexistence of CAKUT with other renal and non-renal morbidities

Types of CAKUT	Comorbidity	Frequency
Posterior urethral valves	Down syndrome	1
Unilateral dysplastic kidney	Hypertrophic pylorus	1
Unilateral dysplastic kidney	Nephrotic syndrome	1
Single kidney	Sickle cell anaemia	2
Posterior urethral valves	Sickle cell anaemia	1
Pelvi-ureteric junction obstruction	Renal abscess	1
Single kidney Single kidney Unilateral dysplastic kidney Total	Nephrotic syndrome Acute kidney injury Congenital hydrocephalus	1 1 1 10

With regards to management, only six children with PUJo had surgical treatment. Four had dismembered pyeloplasty following initial ureterostomy for decompression, while two had outright nephrectomies. The remaining were managed conservatively in the form of regular follow up with ultrasound review. However, for children with PUV, the management approach differed because of the varying ages at presentation. This included long term dwelling catheterization for all of them, vesicostomy for those presenting in the neonatal period and indirect/blind valve ablation.

Discussion

The prevalence of CAKUT among the children with kidney and urinary tract disorders in the present study of 14.87%, falls within the reported rates range from 3.5% to 43% among paediatric population with kidney diseases, from both low- and high-income countries [18–22]. For instance, it is comparable with the 20% reported from South Africa [18] but higher than the 8.62% from Senegal [11]. These differences probably arose from study methodologies. While the current study prospectively collected data spanning a period of 13 years and among children from birth to 18 years, the studies from South Africa and Senegal were retrospective by design. The age brackets of the study populations in both groups are similar to the present study, 2 weeks to 18 years and from birth to 15 years respectively, but vary however in population characteristics. Our study population comprised children from both general paediatric population and those managed in the renal unit. However, theirs were from patients who were seen primarily in the renal unit with already established diagnosis or who were being assessed for CAKUT because of risk such as urinary tract infections. The study from Senegal covered a period of five years in contrast to the much longer duration of the present study.

In the other reports, the study population included both children and adults or those who were primarily diagnosed antenatally with CAKUT [23, 24]. These factors could have contributed to their higher prevalence rates compared with the current study.

Pelvi-ureteric junction obstruction was the most common isolated anomaly identified in this study. This finding is at variant with other reports that showed posterior urethral valves to be the most common [18, 25]. In the report from South Africa, the prevalence of PUV was 45% of all cases of CAKUT reviewed from a single paediatric renal unit over a 10-year period [18]. Similarly, in a study from Egypt, the prevalence of 36.4% was reported among 107 children with CAKUT [25]. It is difficult to state what plausible explanation for these contrasting figures. PUJo is only next to transient or physiologic hydronephrosis as a cause of antenatal hydronephrosis [26]. Furthermore, since PUJo is seen in both genders unlike PUV which is present only in males, it makes sense to suggest that more individuals will be affected. Secondly, in our institution, some of the patients with PUV are sometimes first seen and managed by the paediatric surgeon without recourse to the paediatric renal unit, except and until they observed evidence of impaired renal function either on admission or following valve ablation. This could have influenced the overall numbers of children seen in the paediatric renal unit. In the present study, PUJo occurred more commonly in males (65.38%) and had a predilection for the left kidney in 12 of the 22 children with unilateral presentation, while four had bilateral anomalies.

Posterior urethral valve was the second most common anomaly (20.79%). The mean age at diagnosis was 3.51 years, (range from day one to 14 years). Only four (19.05%) of the 21 children with PUV were diagnosed in the first year of life compared with the 58% and 77% in two other previous South African studies [18, 26]. This difference is due to their higher rates of antenatal detection compared to the abysmally low antenatal detection rate of 8.91% in the current study. The antenatal detection rate observed in the current study is much lower than the international detection rates of 60% to 70% [27], and even the lower rate of 22.41% reported from Senegal [11].

This study is not without limitations. One of these is the limited care offered to the affected children. We are grossly handicapped in some areas of diagnosis and also treatment. Secondly, many of these patients do not have extended follow up so that disease outcomes are clearly characterised. Notwithstanding, this study has provided important information and data on the scope of CAKUT in a setting like ours and also contributing to knowledge.

In conclusion, late diagnosis of children with CAKUT in Nigeria remains a challenge. The commonest type of CAKUT seen in the current study is PUJo. CAKUT can also exist with other comorbidities as shown in the present study. Males are more frequently affected than females. Antenatal detection rate is unacceptably very low. The management of children with CAKUT particularly, those with PUV and PUJo still poses huge challenge. Trained and skilful personnel in paediatric urology are very few and there is near absence of appropriate equipment for diagnosis and treatment in the public tertiary health facilities.

It is recommended that institutional and national guidelines be developed and carefully applied to address the challenges of early diagnosis and treatment, taking into consideration our peculiarities. This will enable care givers to adopt a proactive and effective approach in the care for children with CAKUT. Such approach should also include advocating for and improving skills of health care providers for prenatal detection. In addition, efforts at building capacities and improvement of infrastructures through both collaboration with established health centers and government commitment should be made in this regard.

Authors’ contributions

IEO was responsible for conceiving and designing the research topic. He contributed to data collection, analysis and wrote the draft manuscript.BK, MMI, AOA, PBO and MA all contributed to data collections and made useful contributions to the writing of the manuscriptCA was responsible for reviewing most of the imaging studies and also in carrying out the imaging studies in our facility. He also contributed in writing and review of the manuscriptLC is the paediatric surgeon responsible for the surgical management of some of the patients in this study. He also contributed to manuscript writing and review.

Funding

The authors did not receive any funding for this study.

Data availability

All data used in the current study are available from the corresponding author on reasonable request.

Declarations

Ethics approval and consent to participate

The parents or legal guardians of the children gave written informed consents as well as ascents by older children for appropriate investigations and inclusion into the study. This study was performed in accordance with the Declaration of Helsinki.

Ethical approval was given by the local institutional research ethics committee (IREC), of the Jos University Teaching Hospital Jos (JUTH)

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.