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Pelviureteric junction dysfunction in children
PAEDIATRIC SURGERY II
Pelviureteric junction dysfunction in children
association with calyceal dilatation, but there is rarely ureteric dilatation in isolated PUJD.
Harriet J Corbett
Hydronephrosis of one or both kidneys is detected frequently on antenatal scans; in around 50% of cases this is thought to be due to PUJD. The incidence is approximately 1:750e1:1000. Hydronephrosis is more common on the left than right and is bilateral in 10e20% of cases. There is an increased chance of other urinary tract anomalies such as vesico-ureteric reflux in children with PUJD.
Incidence/demographics
Harish Chandran Karan Parashar Liam McCarthy
Abstract
Aetiology
Hydronephrosis is often caused by pelviureteric junction dysfunction (PUJD). It is frequently detected during antenatal screening. Common causes of PUJD include intrinsic stenosis and aberrant lower pole vessels. Surgery, usually an AndersoneHynes type pyeloplasty, is indicated in patients with symptoms such as pain, infection or haematuria. Asymptomatic patients require a baseline MAG3 scan and serial monitoring with ultrasound scanning. Surgery is indicated if there is increasing hydronephrosis with an anterior posterior diameter (APD) >3 cm, function below 40% or a drop in function of >10% on repeat MAG3.
In most cases there is an intrinsic segment of stenosis at the PUJ which effectively results in dysfunction of the peristaltic wave that moves urine from the pelvis to the ureter. Histopathology of this tissue usually reveals a thin wall with reduced muscle and some fibrosis. In older children, aberrant or additional vessels to the lower pole of the kidney that pass anterior to the PUJ may cause an extrinsic obstruction. Vessels passing behind the PUJ at this point are a normal variant. These ‘crossing vessels’, as they are known, cause around 33% of PUJD in older children. Interestingly they are rarely the cause of hydronephrosis in children less than 4e5 years of age. Other less common causes of PUJD include anatomical ureteric folds or kinks, external fibrous bands, retrocaval positioning of the ureter resulting in compression between the inferior vena cava and spine and fibroepithelial polyps. PUJD can occur in anatomical variants such as horseshoe kidneys and duplex systems (classically in the lower pole). It may also been found as a phenomenon secondary to vesico-ureteric reflux, particularly high grades. Finally, renal calculi can impact at the PUJ and cause obstruction, although non-obstructing calculi may co-exist with PUJD.
Keywords
Antenatal hydronephrosis; antero-posterior diameter; crossing vessels; Dietl’s crisis; hydronephrosis; pelviureteric junction obstruction
Introduction The junction of the renal pelvis with the ureter is known as the pelviureteric junction (PUJ). Suspected dysfunction of this part of the urinary tract is responsible for a considerable number of referrals to urologists, both paediatric and adult. PUJ dysfunction (PUJD) is often called obstruction, but there is rarely a true obstruction at this point. A more accurate description of PUJD is that of abnormal flow of urine from the pelvis to the ureter which results in gradual and progressive damage to the kidney. Typically detected by ultrasound scanning (USS), there is hydronephrosis, that is dilatation of the renal pelvis, often in
Natural history The natural history of antenatally detected PUJD is important. In 27% there is resolution, 56% stay stable whilst 17% of cases will progress, that is the kidney becomes more hydronephrotic or there is functional deterioration.
Presentation
Harriet J Corbett MD FRCS (Paed) is a Specialist Registrar in Paediatric Urology at Birmingham Children’s Hospital, Birmingham, UK. Conflicts of interest: none declared.
PUJD may present in a variety of ways. With the increasing accuracy of antenatal USS, a large number of cases are detected prior to birth although a further small cohort will be detected incidentally during childhood USS for other reasons. The commonest symptomatic presentation is with loin pain, which may be acute or a more insidious aching pain. Acute pain may be associated with loin swelling, both of which resolve after passing a large volume of urine some hours later; such episodes are known as Dietl’s crisis. Other symptomatic presentations include urinary tract infection, pyonephrosis, haematuria and raised blood pressure. PUJD is often discovered following trauma as hydronephrotic kidneys are more vulnerable to injury; symptoms may be precipitated in a previously well patient.
Harish Chandran FRACS (Paed Surg) is a Consultant Urologist at Birmingham Children’s Hospital, Birmingham, UK. Conflicts of interest: none declared. Karan Parashar FRCS (Paed) FEAPU is a Consultant Urologist at Birmingham Children’s Hospital, Birmingham, UK. Conflicts of interest: none declared. Liam McCarthy PhD FRCS (Paed) is a Consultant Urologist at Birmingham Children’s Hospital, Birmingham, UK. Conflicts of interest: none declared.
SURGERY 28:8
391
Ó 2010 Published by Elsevier Ltd.
PAEDIATRIC SURGERY II
Antenatal detection and initial postnatal management
assess the thickness of renal cortex and the rest of the urinary tract. A dilated ureter on the same side does not rule out a PUJ problem. Figure 2 shows the USS images of three patients with differing degrees of hydronephrosis. Isotope renography e MAG3 (99mTechnetium-labelled mercaptoacetyl triglycerine) is given intravenously. MAG3 is taken up by the renal tubules and excreted by a first pass effect. The activity is detected by a gamma camera and processed to give split renal function and excretion (drainage) curves. Often furosemide is given prior to the peak of activity. Analysis of the MAG3 study depends upon split renal function and excretion curves. Figure 3 shows MAG3 images both before and after surgery in a patient with obstruction due to PUJD. Intravenous urogram (IVU) e The IVU (also known as an intravenous pyelogram) may be used in some cases. It is good for showing the anatomy, and if used at the time of pain will help to make the diagnosis (Figure 4). The radiation dose is high, however, so the study is used sparingly. Micturating cystourethrogram (MCUG) e This may be indicated where vesico-ureteric reflux is thought to co-exist or be the cause of hydronephrosis. Retrograde pyelograms are performed in theatre by catheterizing the ureter and are useful for clarifying anatomy. The investigation is utilized in some centres but due to the accuracy of modern USS and isotope renography their use is diminishing.
Hydronephrosis is one of the commonest abnormalities detected on antenatal screening. The differential diagnosis includes vesico-ureteric reflux, posterior urethral valves and megaureter. Additional antenatal investigations may be recommended as hydronephrosis is a soft marker for other disorders including trisomies, particularly trisomy 21. All infants will require a postnatal USS, the timing of which is guided by the antenatal scan findings. Babies with bilateral hydronephrosis, dilated ureters and/or bladder pathology warrant urgent postnatal investigation as they may have bladder outlet obstruction caused by posterior urethral valves. At the other end of the spectrum are babies with very mild unilateral hydronephrosis, in whom the scan may be performed as an outpatient at several weeks of age. All other infants should have a scan after 48 hours of age as relative dehydration and low urine output mean scans prior to this time may appear normal and, thus, falsely reassuring. Most will be followed up by a paediatrician or a paediatric urologist. Infants with an antero-posterior diameter (APD) >10 mm are given antibiotic prophylaxis (normally trimethoprim 2 mg/kg orally at night).
Investigations Ultrasound scans e The degree of hydronephrosis is assessed with USS by measuring the transverse APD of the renal pelvis. The maximal point of dilation is unreliable as it may be extrarenal and depends upon hydration. The APD must therefore be measured correctly at the renal hilum (Figure 1). The upper limit of the normal APD is 8 mm, but the degree of calyceal dilatation must also be considered. In addition, the USS should
Management of symptomatic patients Management of the patient with symptoms from their PUJD is straightforward such that surgery is advised. If the function is good then a pyeloplasty or pyelopexy will usually be performed. If there is poor function in the kidney, that is <10e15% on MAG3, then a nephrectomy may be recommended. Drainage procedures, such as ureteric stenting or nephrostomy, have not been shown to increase function in the affected kidney. Other management options in the symptomatic patient largely depend on the presentation. A child with pyonephrosis in association with PUJD should have a percutaneous nephrostomy inserted, followed by an isotope renogram when the infection has cleared. The function of the affected kidney will dictate the choice of surgery, as above. In rare instances, such as failure of pyeloplasty or where anatomy is awkward, a ureterocalycostomy may be considered.
The kidney in the longitudinal [A] and transverse [B] planes Kidney Pelvis
Anterior
Surgery The AndersoneHynes dismembered pyeloplasty is a tried and tested procedure (Figure 5). It aims to fashion an unobstructed funnel for good urine drainage with the ureter the most dependent part inferiorly. Where there are crossing vessels, the pyeloplasty is performed anterior to the vessels. More recently some surgeons perform a pyelopexy or a pexy of the vessels to separate the vessels and the compressed segment of PUJ. These procedures may be done via an open incision or laparoscopically. The laparoscopic technique, performed via a retroperitoneal or transperitoneal approach, may be quite challenging especially in small children where the working space is limited. One of the current controversies of pyeloplasty surrounds stenting of the anastomosis. An indwelling JJ ureteric stent may be inserted
Posterior Ureter A. Longitudinal view of the kidney. The dashed line indicates the transverse plane
B. Transverse anteroposterior view of the kidney and pelvis showing where the antero-posterior diameter should be measured (arrow)
Figure 1
SURGERY 28:8
392
Ó 2010 Published by Elsevier Ltd.
PAEDIATRIC SURGERY II
Ultrasound images showing varying degrees of hydronephrosis. Images a, c and e are taken in the longitudinal plane and b, d and f in the transverse plane. Images a and b show mild hydronephrosis. Images c and d show moderate hydronephrosis with some calyceal dilatation. Images e and f show severe hydronephrosis with marked calyceal dilatation. Figure 2
pre- or perioperatively. Alternatively a nephrostomy stent (a temporary externalized drain) is used. Studies comparing these methods and stentless surgery have not been able to show any advantage of one method over another. The main disadvantage of the JJ stent is the requirement for a second procedure to remove the stent. Complications of pyeloplasty include urine leak, infection, stenosis of the anastomosis and stone formation. The failure rate of pyeloplasty is <2%. Follow-up after surgery includes an USS and a functional study between 6 months and 1 year. The postoperative imaging takes some time to improve and in some children will never completely return to normal. It should be remembered that the aim of surgery is to preserve function and
SURGERY 28:8
remove symptoms, and not just to improve the imaging appearance.
Management of the asymptomatic patient This group is largely made up of patients with hydronephrosis detected by antenatal USS, but there will be a small number whose hydronephrosis was detected incidentally. The protocol for following patients with hydronephrosis is well established. The aim of management is to preserve function in the affected kidney. Serial monitoring with USS is indicated until the hydronephrosis has stabilized; a baseline MAG3 study is also required. Any significant deterioration in hydronephrosis on USS will
393
Ó 2010 Published by Elsevier Ltd.
PAEDIATRIC SURGERY II
An intravenous urogram in a patient with symptomatic left pelviureteric junction dysfunction (PUJD). The top image is the control film. The bottom film, taken approximately 20 minutes following administration of intravenous contrast, shows bilateral excretion which is normal on the right. On the left the pelvis is dilated with calyceal clubbing due to PUJD. Figure 4
Figure 3 MAG3 studies from the same patient performed before and after left pyeloplasty. Note the slow uptake of tracer in the obstructed left kidney in the preoperative study. The function is good, but the curve demonstrates very poor drainage in comparison to the right kidney. Postoperatively there is prompt uptake and drainage of tracer from both kidneys and function is preserved.
A diagram of a dismembered Anderson-Hynes type pyeloplasty
usually prompt a repeat MAG3. Patients with <40% initial function or a drop in function of >10% in association with PUJD should be considered for surgery. PUJD with >40% function should be managed expectantly if the hydronephrosis is small, but should be managed operatively if the APD is >3 cm. Infants in whom the hydronephrosis was detected antenatally will often be followed up by a paediatric urologist. They should have an MAG3 study and a repeat USS at approximately 3 months of age, with serial USS after that time to monitor the hydronephrosis. All infants except those with hydronephrosis <10 mm should be given antibiotic prophylaxis and this is usually continued for 1e2 years. It should be noted that there is scant evidence for antibiotic prophylaxis, but most surgeons prefer to use it. As with the group above, infants with an APD > 3 cm or function of <40% on MAG3 are candidates for pyeloplasty.
SURGERY 28:8
a
b
c
Figure 5 A diagram of a dismembered AndersoneHynes type pyeloplasty. a shows a narrowed pelviureteric junction (PUJ); the dotted line shows where the ureter is divided. b illustrates ‘fish-mouthing’ the ureter in preparation for anastomosis to the pelvis; the dotted line shows where the pelvis is divided. c shows the completed anastomosis.
394
Ó 2010 Published by Elsevier Ltd.
PAEDIATRIC SURGERY II
Conclusion
Risk of requiring surgery for hydronephrosis
Asymptomatic patients with hydronephrosis thought to be due to PUJD require serial monitoring with USS and a baseline MAG3 scan. Surgery, usually an AndersoneHynes type pyeloplasty, is indicated if there is: function below 40% or a drop in function of >10% on repeat MAG3 increasing hydronephrosis with APD >3 cm. Symptomatic patients usually undergo a pyeloplasty; pyelopexy may be recommended in cases with crossing vessels, whilst those with very poor function are best managed by nephrectomy. A
Degree of Transverse antero-posterior Chance of requiring hydronephrosis diameter (mm) surgery (%) Mild Moderate Severe
<15 15e20 20e30 30e40 >40
Very low 11 40 75 100
Table 1
FURTHER READING Dhillon HK. Prenatally diagnosed hydronephrosis: the Great Ormond Street experience. Br J Urol 1998; 81(suppl 2): 39e44. Gordon I, Dhillon HK, Gatanash H, Peters AM. Antenatal diagnosis of pelvic hydronephrosis: assessment of renal function and drainage as a guide to management. J Nucl Med 1990; 32: 1649e54. Mallik M, Watson AR. Antenatally detected urinary tract abnormalities: more detection but less action. Pediatr Nephrol 2008; 23: 897e904. Thomas DFM, Duffy PG, Rickwood AMK, eds. Essentials of Pediatric Urology. 2nd edn. Informa Healthcare, 2008.
Table 1 outlines the overall risk of requiring surgery in relation to the degree of hydronephrosis (data from the Great Ormond Street Natural History series). Finally, management of the patient with bilateral hydronephrosis may be difficult as there is not a normal kidney to compare to. The same management principles should be followed where possible. In instances where there is a solitary functioning kidney with PUJD, it is accepted practice to undertake a pyeloplasty when the APD is >2 cm.
SURGERY 28:8
395
Ó 2010 Published by Elsevier Ltd.
Pelviureteric junction dysfunction in children
association with calyceal dilatation, but there is rarely ureteric dilatation in isolated PUJD.
Harriet J Corbett
Hydronephrosis of one or both kidneys is detected frequently on antenatal scans; in around 50% of cases this is thought to be due to PUJD. The incidence is approximately 1:750e1:1000. Hydronephrosis is more common on the left than right and is bilateral in 10e20% of cases. There is an increased chance of other urinary tract anomalies such as vesico-ureteric reflux in children with PUJD.
Incidence/demographics
Harish Chandran Karan Parashar Liam McCarthy
Abstract
Aetiology
Hydronephrosis is often caused by pelviureteric junction dysfunction (PUJD). It is frequently detected during antenatal screening. Common causes of PUJD include intrinsic stenosis and aberrant lower pole vessels. Surgery, usually an AndersoneHynes type pyeloplasty, is indicated in patients with symptoms such as pain, infection or haematuria. Asymptomatic patients require a baseline MAG3 scan and serial monitoring with ultrasound scanning. Surgery is indicated if there is increasing hydronephrosis with an anterior posterior diameter (APD) >3 cm, function below 40% or a drop in function of >10% on repeat MAG3.
In most cases there is an intrinsic segment of stenosis at the PUJ which effectively results in dysfunction of the peristaltic wave that moves urine from the pelvis to the ureter. Histopathology of this tissue usually reveals a thin wall with reduced muscle and some fibrosis. In older children, aberrant or additional vessels to the lower pole of the kidney that pass anterior to the PUJ may cause an extrinsic obstruction. Vessels passing behind the PUJ at this point are a normal variant. These ‘crossing vessels’, as they are known, cause around 33% of PUJD in older children. Interestingly they are rarely the cause of hydronephrosis in children less than 4e5 years of age. Other less common causes of PUJD include anatomical ureteric folds or kinks, external fibrous bands, retrocaval positioning of the ureter resulting in compression between the inferior vena cava and spine and fibroepithelial polyps. PUJD can occur in anatomical variants such as horseshoe kidneys and duplex systems (classically in the lower pole). It may also been found as a phenomenon secondary to vesico-ureteric reflux, particularly high grades. Finally, renal calculi can impact at the PUJ and cause obstruction, although non-obstructing calculi may co-exist with PUJD.
Keywords
Antenatal hydronephrosis; antero-posterior diameter; crossing vessels; Dietl’s crisis; hydronephrosis; pelviureteric junction obstruction
Introduction The junction of the renal pelvis with the ureter is known as the pelviureteric junction (PUJ). Suspected dysfunction of this part of the urinary tract is responsible for a considerable number of referrals to urologists, both paediatric and adult. PUJ dysfunction (PUJD) is often called obstruction, but there is rarely a true obstruction at this point. A more accurate description of PUJD is that of abnormal flow of urine from the pelvis to the ureter which results in gradual and progressive damage to the kidney. Typically detected by ultrasound scanning (USS), there is hydronephrosis, that is dilatation of the renal pelvis, often in
Natural history The natural history of antenatally detected PUJD is important. In 27% there is resolution, 56% stay stable whilst 17% of cases will progress, that is the kidney becomes more hydronephrotic or there is functional deterioration.
Presentation
Harriet J Corbett MD FRCS (Paed) is a Specialist Registrar in Paediatric Urology at Birmingham Children’s Hospital, Birmingham, UK. Conflicts of interest: none declared.
PUJD may present in a variety of ways. With the increasing accuracy of antenatal USS, a large number of cases are detected prior to birth although a further small cohort will be detected incidentally during childhood USS for other reasons. The commonest symptomatic presentation is with loin pain, which may be acute or a more insidious aching pain. Acute pain may be associated with loin swelling, both of which resolve after passing a large volume of urine some hours later; such episodes are known as Dietl’s crisis. Other symptomatic presentations include urinary tract infection, pyonephrosis, haematuria and raised blood pressure. PUJD is often discovered following trauma as hydronephrotic kidneys are more vulnerable to injury; symptoms may be precipitated in a previously well patient.
Harish Chandran FRACS (Paed Surg) is a Consultant Urologist at Birmingham Children’s Hospital, Birmingham, UK. Conflicts of interest: none declared. Karan Parashar FRCS (Paed) FEAPU is a Consultant Urologist at Birmingham Children’s Hospital, Birmingham, UK. Conflicts of interest: none declared. Liam McCarthy PhD FRCS (Paed) is a Consultant Urologist at Birmingham Children’s Hospital, Birmingham, UK. Conflicts of interest: none declared.
SURGERY 28:8
391
Ó 2010 Published by Elsevier Ltd.
PAEDIATRIC SURGERY II
Antenatal detection and initial postnatal management
assess the thickness of renal cortex and the rest of the urinary tract. A dilated ureter on the same side does not rule out a PUJ problem. Figure 2 shows the USS images of three patients with differing degrees of hydronephrosis. Isotope renography e MAG3 (99mTechnetium-labelled mercaptoacetyl triglycerine) is given intravenously. MAG3 is taken up by the renal tubules and excreted by a first pass effect. The activity is detected by a gamma camera and processed to give split renal function and excretion (drainage) curves. Often furosemide is given prior to the peak of activity. Analysis of the MAG3 study depends upon split renal function and excretion curves. Figure 3 shows MAG3 images both before and after surgery in a patient with obstruction due to PUJD. Intravenous urogram (IVU) e The IVU (also known as an intravenous pyelogram) may be used in some cases. It is good for showing the anatomy, and if used at the time of pain will help to make the diagnosis (Figure 4). The radiation dose is high, however, so the study is used sparingly. Micturating cystourethrogram (MCUG) e This may be indicated where vesico-ureteric reflux is thought to co-exist or be the cause of hydronephrosis. Retrograde pyelograms are performed in theatre by catheterizing the ureter and are useful for clarifying anatomy. The investigation is utilized in some centres but due to the accuracy of modern USS and isotope renography their use is diminishing.
Hydronephrosis is one of the commonest abnormalities detected on antenatal screening. The differential diagnosis includes vesico-ureteric reflux, posterior urethral valves and megaureter. Additional antenatal investigations may be recommended as hydronephrosis is a soft marker for other disorders including trisomies, particularly trisomy 21. All infants will require a postnatal USS, the timing of which is guided by the antenatal scan findings. Babies with bilateral hydronephrosis, dilated ureters and/or bladder pathology warrant urgent postnatal investigation as they may have bladder outlet obstruction caused by posterior urethral valves. At the other end of the spectrum are babies with very mild unilateral hydronephrosis, in whom the scan may be performed as an outpatient at several weeks of age. All other infants should have a scan after 48 hours of age as relative dehydration and low urine output mean scans prior to this time may appear normal and, thus, falsely reassuring. Most will be followed up by a paediatrician or a paediatric urologist. Infants with an antero-posterior diameter (APD) >10 mm are given antibiotic prophylaxis (normally trimethoprim 2 mg/kg orally at night).
Investigations Ultrasound scans e The degree of hydronephrosis is assessed with USS by measuring the transverse APD of the renal pelvis. The maximal point of dilation is unreliable as it may be extrarenal and depends upon hydration. The APD must therefore be measured correctly at the renal hilum (Figure 1). The upper limit of the normal APD is 8 mm, but the degree of calyceal dilatation must also be considered. In addition, the USS should
Management of symptomatic patients Management of the patient with symptoms from their PUJD is straightforward such that surgery is advised. If the function is good then a pyeloplasty or pyelopexy will usually be performed. If there is poor function in the kidney, that is <10e15% on MAG3, then a nephrectomy may be recommended. Drainage procedures, such as ureteric stenting or nephrostomy, have not been shown to increase function in the affected kidney. Other management options in the symptomatic patient largely depend on the presentation. A child with pyonephrosis in association with PUJD should have a percutaneous nephrostomy inserted, followed by an isotope renogram when the infection has cleared. The function of the affected kidney will dictate the choice of surgery, as above. In rare instances, such as failure of pyeloplasty or where anatomy is awkward, a ureterocalycostomy may be considered.
The kidney in the longitudinal [A] and transverse [B] planes Kidney Pelvis
Anterior
Surgery The AndersoneHynes dismembered pyeloplasty is a tried and tested procedure (Figure 5). It aims to fashion an unobstructed funnel for good urine drainage with the ureter the most dependent part inferiorly. Where there are crossing vessels, the pyeloplasty is performed anterior to the vessels. More recently some surgeons perform a pyelopexy or a pexy of the vessels to separate the vessels and the compressed segment of PUJ. These procedures may be done via an open incision or laparoscopically. The laparoscopic technique, performed via a retroperitoneal or transperitoneal approach, may be quite challenging especially in small children where the working space is limited. One of the current controversies of pyeloplasty surrounds stenting of the anastomosis. An indwelling JJ ureteric stent may be inserted
Posterior Ureter A. Longitudinal view of the kidney. The dashed line indicates the transverse plane
B. Transverse anteroposterior view of the kidney and pelvis showing where the antero-posterior diameter should be measured (arrow)
Figure 1
SURGERY 28:8
392
Ó 2010 Published by Elsevier Ltd.
PAEDIATRIC SURGERY II
Ultrasound images showing varying degrees of hydronephrosis. Images a, c and e are taken in the longitudinal plane and b, d and f in the transverse plane. Images a and b show mild hydronephrosis. Images c and d show moderate hydronephrosis with some calyceal dilatation. Images e and f show severe hydronephrosis with marked calyceal dilatation. Figure 2
pre- or perioperatively. Alternatively a nephrostomy stent (a temporary externalized drain) is used. Studies comparing these methods and stentless surgery have not been able to show any advantage of one method over another. The main disadvantage of the JJ stent is the requirement for a second procedure to remove the stent. Complications of pyeloplasty include urine leak, infection, stenosis of the anastomosis and stone formation. The failure rate of pyeloplasty is <2%. Follow-up after surgery includes an USS and a functional study between 6 months and 1 year. The postoperative imaging takes some time to improve and in some children will never completely return to normal. It should be remembered that the aim of surgery is to preserve function and
SURGERY 28:8
remove symptoms, and not just to improve the imaging appearance.
Management of the asymptomatic patient This group is largely made up of patients with hydronephrosis detected by antenatal USS, but there will be a small number whose hydronephrosis was detected incidentally. The protocol for following patients with hydronephrosis is well established. The aim of management is to preserve function in the affected kidney. Serial monitoring with USS is indicated until the hydronephrosis has stabilized; a baseline MAG3 study is also required. Any significant deterioration in hydronephrosis on USS will
393
Ó 2010 Published by Elsevier Ltd.
PAEDIATRIC SURGERY II
An intravenous urogram in a patient with symptomatic left pelviureteric junction dysfunction (PUJD). The top image is the control film. The bottom film, taken approximately 20 minutes following administration of intravenous contrast, shows bilateral excretion which is normal on the right. On the left the pelvis is dilated with calyceal clubbing due to PUJD. Figure 4
Figure 3 MAG3 studies from the same patient performed before and after left pyeloplasty. Note the slow uptake of tracer in the obstructed left kidney in the preoperative study. The function is good, but the curve demonstrates very poor drainage in comparison to the right kidney. Postoperatively there is prompt uptake and drainage of tracer from both kidneys and function is preserved.
A diagram of a dismembered Anderson-Hynes type pyeloplasty
usually prompt a repeat MAG3. Patients with <40% initial function or a drop in function of >10% in association with PUJD should be considered for surgery. PUJD with >40% function should be managed expectantly if the hydronephrosis is small, but should be managed operatively if the APD is >3 cm. Infants in whom the hydronephrosis was detected antenatally will often be followed up by a paediatric urologist. They should have an MAG3 study and a repeat USS at approximately 3 months of age, with serial USS after that time to monitor the hydronephrosis. All infants except those with hydronephrosis <10 mm should be given antibiotic prophylaxis and this is usually continued for 1e2 years. It should be noted that there is scant evidence for antibiotic prophylaxis, but most surgeons prefer to use it. As with the group above, infants with an APD > 3 cm or function of <40% on MAG3 are candidates for pyeloplasty.
SURGERY 28:8
a
b
c
Figure 5 A diagram of a dismembered AndersoneHynes type pyeloplasty. a shows a narrowed pelviureteric junction (PUJ); the dotted line shows where the ureter is divided. b illustrates ‘fish-mouthing’ the ureter in preparation for anastomosis to the pelvis; the dotted line shows where the pelvis is divided. c shows the completed anastomosis.
394
Ó 2010 Published by Elsevier Ltd.
PAEDIATRIC SURGERY II
Conclusion
Risk of requiring surgery for hydronephrosis
Asymptomatic patients with hydronephrosis thought to be due to PUJD require serial monitoring with USS and a baseline MAG3 scan. Surgery, usually an AndersoneHynes type pyeloplasty, is indicated if there is: function below 40% or a drop in function of >10% on repeat MAG3 increasing hydronephrosis with APD >3 cm. Symptomatic patients usually undergo a pyeloplasty; pyelopexy may be recommended in cases with crossing vessels, whilst those with very poor function are best managed by nephrectomy. A
Degree of Transverse antero-posterior Chance of requiring hydronephrosis diameter (mm) surgery (%) Mild Moderate Severe
<15 15e20 20e30 30e40 >40
Very low 11 40 75 100
Table 1
FURTHER READING Dhillon HK. Prenatally diagnosed hydronephrosis: the Great Ormond Street experience. Br J Urol 1998; 81(suppl 2): 39e44. Gordon I, Dhillon HK, Gatanash H, Peters AM. Antenatal diagnosis of pelvic hydronephrosis: assessment of renal function and drainage as a guide to management. J Nucl Med 1990; 32: 1649e54. Mallik M, Watson AR. Antenatally detected urinary tract abnormalities: more detection but less action. Pediatr Nephrol 2008; 23: 897e904. Thomas DFM, Duffy PG, Rickwood AMK, eds. Essentials of Pediatric Urology. 2nd edn. Informa Healthcare, 2008.
Table 1 outlines the overall risk of requiring surgery in relation to the degree of hydronephrosis (data from the Great Ormond Street Natural History series). Finally, management of the patient with bilateral hydronephrosis may be difficult as there is not a normal kidney to compare to. The same management principles should be followed where possible. In instances where there is a solitary functioning kidney with PUJD, it is accepted practice to undertake a pyeloplasty when the APD is >2 cm.
SURGERY 28:8
395
Ó 2010 Published by Elsevier Ltd.