|Year : 2014 | Volume
| Issue : 4 | Page : 169-173
Out-patient percutaneous renal biopsy among children in Northern Nigeria: A single center experience
Patience N Obiagwu1, Aliyu Abdu2, Akinfenwa T Atanda3
1 Department of Paediatrics, Aminu Kano Teaching Hospital; Department of Histopathology, Bayero University, Kano, Nigeria
2 Department of Medicine, Aminu Kano Teaching Hospital; Department of Histopathology, Bayero University, Kano, Nigeria
3 Department of Histopathology, Aminu Kano Teaching Hospital; Department of Histopathology, Bayero University, Kano, Nigeria
|Date of Web Publication||7-Oct-2014|
Patience N Obiagwu
Department of Paediatrics, Aminu Kano Teaching Hospital, Kano
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Background: The safety of percutaneous renal biopsy (PRB) has been debated. The primary aim of this study was to review the procedure and secondary aim is to evaluate the safety of PRB in children in a developing nephrology unit in Northern Nigeria.
Methods: Renal biopsies carried out in the renal unit of a teaching hospital in northern Nigeria between November 2011 and April 2013 were retrospectively reviewed. All biopsies were carried out electively and under real-time ultrasound guidance using an automatic spring-loaded biopsy gun. Risk factors for complications were analyzed using logistic regression.
Results: A total of 24 biopsies were carried out in 20 children with nephrotic syndrome during the period under review. Mean age was 8.3 3.0 years. Steroid resistant nephrotic syndrome was the most common indication for biopsy in 11 (55%) cases. Adequate tissue was obtained in 91.7%. Complications occurred in 2 (8.3%) cases. One required hospitalization with blood transfusion. Pre-biopsy hemoglobin concentration of <10 g/dL was found to be a significant predictor for the development of complications (P < 0.05). There was no significant difference in the rate of complications between the in-patient biopsies and day case biopsies.
Conclusions: PRB can be safely carried out as an out-patient procedure in children. Low hemologlobin concentration was the major risk factor for complication.
| Abstract in French|| |
Contexte: La sιcuritι de la biopsie rιnale percutanιe ( PRB ) a ιtι dιbattue. L'objectif principal de cette ιtude ιtait d'examiner la procιdure et objectif secondaire est d'ιvaluer la sιcuritι de PRB chez les enfants dans un service de nιphrologie de dιveloppement dans le nord du Nigeria.
Mιthodes: Biopsies rιnales rιalisιes dans le service de nιphrologie d'un hτpital d'enseignement dans le nord du Nigeria entre Novembre 2011 et Avril 2013 ont ιtι revus rιtrospectivement. Toutes les biopsies ont ιtι rιalisιes ιlectivement et sous contrτle ιchographique en temps rιel en utilisant un pistolet ΰ biopsie ressort automatique . Les facteurs de risque de complications ont ιtι analysιs par rιgression logistique.
Rιsultats: Un total de 24 biopsies ont ιtι rιalisιes chez 20 enfants atteints du syndrome nιphrotique au cours de la pιriode sous revue. L'βge moyen ιtait de 8,3 3,0 ans. Syndrome nιphrotique rιsistant aux stιroοdes ιtait l'indication la plus commune pour une biopsie dans 11 (55%) des cas. Tissulaire adιquate a ιtι obtenue dans 91,7 %. Des complications sont survenues dans deux (8,3%) cas. Une hospitalisation nιcessaire ΰ la transfusion sanguine. La concentration en hιmoglobine prι- biopsie de <10 g/dl s'est avιrι κtre un facteur prιdictif significatif pour le dιveloppement de complications (P < 0,05 ). Il n'y avait pas de diffιrence significative dans le taux de complications entre les biopsies de patients et cas de biopsies jour .
Conclusions: PRB peut κtre effectuι en toute sιcuritι comme une procιdure ambulatoire chez l'enfant . Concentration de hemologlobin bas a ιtι le principal facteur de risque de complication.
Mots-clιs: Enfants, le Nigeria, les rιsultats, la biopsie rιnale percutanιe
Keywords: Children, Nigeria, outcomes, percutaneous renal biopsy
|How to cite this article:|
Obiagwu PN, Abdu A, Atanda AT. Out-patient percutaneous renal biopsy among children in Northern Nigeria: A single center experience. Ann Afr Med 2014;13:169-73
|How to cite this URL:|
Obiagwu PN, Abdu A, Atanda AT. Out-patient percutaneous renal biopsy among children in Northern Nigeria: A single center experience. Ann Afr Med [serial online] 2014 [cited 2019 Nov 21];13:169-73. Available from: http://www.annalsafrmed.org/text.asp?2014/13/4/169/142286
| Introduction|| |
A percutaneous approach to renal biopsy was introduced in 1951. , Over time, advances in imaging techniques and the use of automated biopsy needles have made the procedure safe and diagnostic in over 95% of biopsies.  Percutaneous renal biopsy (PRB) is important in diagnosing the cause of renal disease, prognosticating as well as monitoring response to therapy.  The use of the real-time ultrasound-guided technique for PRB has been known to result in better tissue yield with fewer complications when compared with the blinded technique.  The safety of performing biopsies as out-patient or day case procedures has also been documented, ,, as well as risks associated with sedation. , Complications of renal biopsy have also been documented by several authors with complication rates ranging between 0% and 30% respectively. ,
Published works on percutaneous renal biopsies in Nigerian children are very few. The study from the northern part of Nigeria is over two decades old.  Real-time, ultrasound-guided PRB was commenced on a regular basis in 2011 in the renal unit in which this study was conducted and it summarizes our experience with PRB.
| Materials and Methods|| |
This is a retrospective review of renal biopsies carried out on patients with nephrotic syndrome in the pediatric nephrology unit of the teaching hospital, from November 2011 to April 2013. The teaching hospital has clientele which also includes patients from several surrounding states including Zamfara, Katsina, Jigawa, Bauchi, Gombe and Yobe states. The renal biopsies were performed by the Pediatric Nephrologist with at least two other resident doctors present to assist. The children who had PRB were those with either steroid resistant or frequently relapsing nephrotic syndrome and those with atypical features of nephrotic syndrome prior to commencement of steroid therapy. All biopsies were performed on native kidneys and as elective procedures after obtaining consent/assent from the caregivers/subjects prior to the procedure.
Following unit protocols, pre-biopsy tests were conducted and these included full blood counts, coagulation profile, renal function tests, urinalysis, urine microscopy and abdominal ultrasonography. Grounds for exclusion from renal biopsy included uncontrolled hypertension, significant anemia (hemoglobin concentration <7 g/dL and/or associated with symptoms of decompensation), abnormal coagulation profile, acute urinary tract infection and a solitary kidney. All patients reported to the unit on the morning of the procedure after having fasted for at least 6 h and had an intravenous access established, usually on the dorsum of the hand. Real time ultrasonography guidance with a conve × 3.5 MHz transducer was used throughout the procedure (Mindray DP-6600 ultrasound unit, Shenzhen, P. R. China).
During the procedure, the patient is laid prone on the bed with a firm pillow placed under the abdomen. Kidney sizes are measured and the depth from the skin to the cortex was determined with ultrasound. Sedation is achieved using 0.3-0.6 mg/kg/dose of diazepam and 0.5-0.8 mg/kg/dose of pentazocine administered intravenously to each patient. Vital signs are monitored throughout the procedure.
The lower pole of the left kidney is then identified and was used in all cases as there were no contraindications necessitating using the right. Following sterile procedures, 1% lignocaine is infiltrated from the skin into the kidney capsule. A 16-gauge automated spring-loaded disposable core biopsy needle with a 22 mm sample length (Bard Monopty gun, C. R. Bard Inc., Arizona, USA) was used to obtain kidney tissue in all biopsies. It is advanced under real time ultrasonographic vision down into the cortex to the predetermined depth and a minimum of two tissue cores are taken. Each biopsy specimen is fixed and transported in 10% buffered formalin solution for analysis in the pathology laboratory of the hospital where they are embedded in paraffin wax and stained with hematoxylin and eosin, periodic acid-Schiff, Masson's Trichrome stain and Jones silver stains. Only light microscopy was performed on the tissue samples. An adequate sample was defined as one in which the Histopathologist was able to make a histological diagnosis and it usually included more than eight glomeruli. After biopsy, firm occlusive dressing is then placed on the biopsy site and the patient is left to lie on his/her back for the next 6 h. Intravenous fluid is left to run or the child is allowed to drink liberally if fully awake. Vital signs are monitored every 15 min for the first hour, half hourly for the next hour and then hourly thereafter for the period of observation, which lasted 8 h on the average. A urine rack is kept to monitor the appearance of the urine passed during the period of observation.
Data retrieved included the age, gender, number of passes per patient, number of adequate and inadequate samples, core lengths, number of glomeruli per core, serum urea and creatinine levels, pre and post biopsy hemoglobin levels, complications after biopsy and histological diagnosis. Major complications were considered to be those which required a blood transfusion, surgical intervention or extended hospitalization. Categorical variables were presented as frequencies and percentages while quantitative data was expressed as mean ± standard deviation. Multiple logistic regression was performed to determine which of the variables was predictive of the development of a complication after renal biopsy. Data analysis was carried out using the SPSS version 16.0 for Windows (SPSS Inc., Chicago, USA).
| Results|| |
In the study period, 26 pediatric nephrology cases requiring PRB were seen. However, the procedure was performed in only 20 patients in 24 attempts. There were 17 males and 3 females (M:F = 5.7:1). The mean age was 8.3 ± 3.0 years. Prior to biopsy, three children (15%) were already on admission for other reasons. The demographic characteristics are shown in [Table 1]. Steroid resistant nephrotic syndrome was the most common indication for biopsy in 11 (55%) cases. Other indications included frequently relapsing nephrotic syndrome in 3 (15%) cases and presence of atypical features on initial presentation in 6 (30%) cases.
Four biopsies had inadequate tissue specimens and of these, two were repeated with success. PRB was thus successful with adequate tissue obtained in 91.7% (22/24). Complications occurred in 2 biopsies (8.3%). One of them had vague abdominal pain over the biopsy site while the other had a persistent, painless gross hematuria. There was no procedure-related death or complication requiring surgical intervention. There were no complications arising from the sedation protocol. Therefore, 91.7% of biopsies were free from complications. In 21 biopsies, the children were fully awake and able to drink orally while intravenous fluids post-biopsy were only required in three cases.
Repeat abdominal ultrasound scan in the patient who had complained of abdominal pain about 3 h post-biopsy revealed a mild perinephric hematoma. He was admitted for observation. Subsequent abdominal ultrasound 2 days later confirmed resolution of the haematoma. The patient who had persistent painless gross hematuria was also admitted. Pelvic ultrasound revealed a developing intravesical hematoma. He had repeated sessions of bladder irrigation with saline and the hematoma resolved after a few days. He also received a packed cell transfusion. The three children who were on admission for other clinical reasons prior to renal biopsy did not have any biopsy-related complications.
Among the variables tested, significant differences were found when pre-biopsy hemoglobin concentration of <10 g/dL, change in pre- and post-biopsy haemoglobin concentration of >1 g/dL and the histological subtype of focal segmental glomerulosclerosis were compared with the presence of complications as shown in [Table 2]. On multiple logistic regression analysis, only the pre-biopsy hemoglobin concentration <10 g/dL was found to be a significant predictor of the development of complications. There was no significant difference in the rate of complications between the biopsies that were performed as in-patient procedures and those that were performed on an out-patient basis.
| Discussion|| |
The complication rate in out-patient PRB in this study was 8.3%. This is comparable to that reported by Piotto et al.  in a recent study in Brazil. It is also comparable with the 8.7% reported in a previous study done almost three decades ago in northern Nigeria by Abdurrahman.  However, it is much higher than the 1.8% reported in a recent review of PRB done in Norway over a period of 22 years in over 9000 adults and children.  Other studies have reported varied complication rates ranging between 4% and 15%. ,,],,, It is known that renal biopsy in children is not as easily performed as in adults due to a lack of cooperation, kidney mobility and smaller size.  However, the practice of sedation, the use of automated needles and real-time ultrasonographic monitoring as well as the performance of PRB as a day case procedure have made the procedure much easier to perform with fewer complications and at lower costs. ,,,],,,,,
Mild perinephric hematoma was included as a complication in this study because PRBs were only recently being performed regularly in children and every complication was being observed. Some authors have however indicated that perinephric hematomas should not be regarded as a clinically significant complication. , Intravesical clot has been reported as a complication following renal biopsy in children. 
This study also shows that PRBs can be performed safely as day cases. However, it is worthy of note that all biopsies in this series were elective and biopsy criteria according to the unit protocols were followed. Whittier and Korbet  concluded that the practice of PRB as a day case procedure was strictly for cost saving reasons and based his assumptions on studies which had been carried out on small numbers of select patients and with biopsies performed by limited numbers of experienced nephrologists. However, the safety of performing renal biopsies as day case procedures has been documented in recent studies by several authors ,,, as well as in much older studies in children in the USA  and in Nigerian adults. 
The adequacy rate of 91.7% obtained in this study was slightly lower than those of most other studies in children. ,,,,,, This could be attributed to the fact that the procedure was relatively new in pediatrics in the hospital and experience was being developed. It has been documented that centers which perform an average of more than 30 biopsies a year have fewer complication rates due to activity and experience in the procedure.  However, in Nigeria, the frequency of practice of renal biopsy appears to be on a downward trend. This is probably because of the prohibitive costs and the lack of ready availability of renal biopsy needles, as well as a comparative lack of persons skilled in the procedure. The slightly lower adequacy rate could also be attributed to the use of one needle size for children of all ages. It has been documented that the 14G needles can be used for children older than 8 years of age but with efforts made to minimize possible complications. 
The age range of the children who had renal biopsy was 2½-13 years. The mean age of 8.3 years corresponds with those of other studies, ,,,, but much lower than the median age of 11.8 years reported in a recent audit performed in the UK.  The most common indication for biopsy in this study was nephrotic syndrome which was also similar to those of other studies. ,,,,,,,
This study was limited by the inability to perform repeat ultrasound scans hours after the procedure. It was only done in patients who had exhibited symptoms suggestive of complications. It is possible that mild, asymptomatic perinephric hematomas may have been missed. However, this would not be expected to have had significant effects on patient outcomes. The small number of subjects and the retrospective nature of the study were also limitations. It is therefore recommended that prospective studies be carried out using larger numbers of subjects.
| Conclusion|| |
PRB can be carried out safely as a day case procedure in children. The use of real-time ultrasound guidance as well as the automated biopsy gun also gives the assurance of fewer complications. This is especially so when PRB is performed as an elective procedure. It is thus important for nephrologists and residents alike to be trained in performing this procedure so as to hone their skills and ultimately lead to an improvement in diagnostic capacity in renal conditions requiring histological confirmation.
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[Table 1], [Table 2]