10.5.1 Infection

After the progressive diminution of renal function, infection is the most important complication. In the presence of obstruction, urine in the renal pelvis is leading freely into the renal lymphatics, and if the urine is infected, organisms readily enter the bloodstream. Septicaemia is an ever‐present risk. The curious thing is how often patients seem to remain well despite having a kidney full of purulent urine.

When pyonephrosis is encountered, the first step should be to drain it by means of a percutaneous nephrostomy. For the first few days, thick pus will drain away but will soon be followed by the production of a useful quantity of urine. The creatinine concentration in this urine should be measured from time to time until it becomes stable before making a decision as to whether to try to save the kidney or perform a nephrectomy.

10.5.2 Stones

Stones readily form in the pool of stagnant urine in hydronephrosis. They are multiple and rounded like pebbles from the seashore in contrast to those stones which arise within the kidney and give rise to secondary obstruction and hydronephrosis. The latter are not smooth, and they retain the shape of the renal pelvis and its calices. When it is not easy to be sure whether the obstruction or the stone came first, a version of the Whitaker test may be used at operation or after percutaneous nephrolithotomy to see if there is an idiopathic obstruction at the pelviureteric junction.

10.5.3 Trauma

It is easier to burst a balloon when it is blown up, and for the same reason, a distended hydronephrosis is apt to be ruptured by external injury. The urogram performed as an emergency soon after the patient is admitted with suspected closed renal injury may show the unexpected coexistence of a hydronephrosis and extravasation of urine, but more often the renal function is too poor to display the anatomy of the kidney. A CT scan will show the thinned out parenchyma. This sometimes raises a medicolegal question; did the injury cause the hydronephrosis? This may be easy to answer if the renal parenchyma is already severely atrophied at the time of injury. In other cases, it is impossible to be sure that the injury was not responsible for the obstruction.

10.5.4 Hypertension

Hypertension associated with a hydronephrosis may resolve with cure of the obstruction. In former days, the lower pole artery used to be divided because it was believed to be causing the obstruction (Figure 10.1b), and in these cases, hypertension was a common sequel to the infarction of the lower pole.

10.8.1 Pathogenesis

PUJ obstruction can be congenital or acquired. In congenital, the causes are more likely intrinsic; however, extrinsic crossing vessels may contribute. PUJ obstruction the common pathology is of intrinsic luminal disease. Under normal physiology, the pacemakers of urine propagation, which lie in the minor renal calices, contract to direct urine down to the renal pelvis and ureters. The proximal ureter is open and accommodates the urine by stretch, which subsequently stimulates downstream flow by peristalsis. In PUJ obstruction, the proximal ureter is not receptive to the urine load, thus raising the pressures required to allow urine delivery into the ureter to above normal. This leads to the contraction dissociation of both the distal renal pelvis from the proximal ureter, as well as the proximal renal pelvis from the distal pelvis. As a consequence, the renal pelvis becomes increasingly dilated as pacemaker‐induced contractions become more ineffective. This dilatation is accelerated by the inefficient urine transport secondary to the reduced peristaltic transmission as well as reduced urinary bolus volumes.

A frequently found defect is an aperistaltic ureteric segment with abnormal fibrous tissue and longitudinal muscle fibres replacing the normal spiral musculature. Less frequently, the subject can have a primary ureteric stricture, due to excessive collagen deposition, which can occur anywhere throughout the lumbar ureter but most frequently are situated at the PUJ (Figure 10.4).

Abnormal folds of ureteral mucosa and musculature, retained from foetal development, can lead to kinks or valves. In some, a complete adventitial bridge can be retained leading to ureteral bands and adhesions. These congenitally retained folds can occasionally produce an angle of entry of the ureter to the distal renal pelvis in such a manner that the pelvis dilates inferiorly and anteriorly, with a resultant proximal ureteric insertion. This leads to inadequate drainage of the most dependent part of the renal pelvis. Although commonly a secondary phenomenon, high ureteric insertion can rarely be a primary congenital pathology.

The role of aberrant crossing vessels in causing extrinsic PUJ obstruction is still debatable (Figure 10.1). Studies have shown that 63% of patients with PUJ obstruction have aberrant crossing vessels on cross‐sectional imaging [26]. However, many of these patients with evidence of crossing vessels also have intrinsic luminal pathology causing renal pelvis dilatation, which subsequently balloons and impinges on to the crossing vessels [27]. Nonetheless, studies have found improvement in obstruction with ligation of aberrant vessels alone, suggesting this is the primary cause [28].

Acquired causes are more commonly caused by intrinsic causes rather than extrinsic compression. Intrinsic causes include trauma from a stone or endoluminal procedures (ureteroscopy), and urothelial tumours at the PUJ (polyps or malignancy). Extrinsic causes include retroperitoneal fibrosis, malignancy, or iatrogenic injury.

10.8.2 Natural History and Presentation

PUJ obstruction most commonly is a congenital problem; however, it can present at any stage of life. It has a variable natural history. Due to the widespread use of antenatal sonography, there has been a dramatic rise in the diagnosis of asymptomatic hydronephrosis in newborns. Obstruction can resolve spontaneously in some cases, whereas with others it increases in severity with deterioration in renal function. It can also remain stable for years in many patients (Table 10.6). It can occasionally present in a previously normal or mildly dilated kidney. A study of conservatively managed children with an antenatal diagnosis of PUJ obstruction showed 17% required surgical intervention due to worsening obstruction, 27% had spontaneously resolved obstruction, and 56% had stable disease with no deterioration in obstruction or renal function [29].

10.8.3 Investigations

Radiological modalities should be targeted at determining the anatomical site and functional significance of the suspected obstruction. Usually the first‐line investigation in children is ultrasonography. This can visualise the dilated collecting system and can determine the level of obstruction. In adults, a CT scan is standard protocol for patients with loin pain, or contrast‐enhanced CT urogram for patients with haematuria. Both modalities will accurately give you anatomical information regarding site of obstruction with CT urogram giving you functional data as well (Figure 10.5).

Diuretic renography, most commonly mercaptoacetyltriglycine‐3 (MAG3) dynamic renogram, is used in the evaluation of PUJ obstruction (Figure 10.6). It gives functional information as well as quantitative data regarding split renal function and is a valuable tool to assess the success of surgical treatments. DMSA scan is useful in patients with poor renal function in determining whether a reconstructive procedure or nephrectomy would be the most appropriate surgical intervention.

10.8.4 Management

If patients with suspected PUJ obstruction do not fulfil the criteria for surgical intervention, then close monitoring with serial diuretic renography may be appropriate.

The indications for intervention are:

• progressive decline in unilateral split function.
  
• impairment in overall renal function.
  
• obstruction associated symptoms (pain or haematuria).
  
• infection episodes (pyonephrosis).
  
• renal tract stone development.
  
• secondary hypertension.

Different endourological and open, laparoscopic, and robotic procedures have been described to treat PUJ obstruction. Age and comorbidities play a major role in decision making because a patient who is elderly and comorbid may be suitable for conservative monitoring or long‐term ureteral stenting, whereas reconstructive surgery would be most appropriate for a paediatric patient to potentially reverse renal dysfunction.

10.8.5 Pyeloplasty

Laparoscopic or robotic pyeloplasty are the current gold standard of treating PUJ obstruction because they are associated with quicker recovery and discharge from hospital and less postoperative morbidity and a low risk of conversion [30]. Laparoscopy can be done either by the more common transperitoneal or retroperitoneal approach. Robotic pyeloplasty is usually done via a transperitoneal approach. The steps of the procedure are identical regardless of approach.

Though minimally invasive techniques have replaced open pyeloplasty, the techniques of the procedures are similar. Anderson and Hynes popularised their novel technique in the middle of the twentieth century. It can be used almost universally for different PUJ obstruction scenarios even when there is a high ureteric insertion into the renal pelvis as well as when it is already dependent. It is the sole procedure that completely excises the abnormal PUJ itself. Its use is more debatable in situations with a predominantly inaccessible intrarenal pelvis or long proximal ureteric stricture. Nonetheless, the key principle is the use of a wide, well‐vascularized flap of renal pelvis to enlarge the narrow part of the ureter. Essential to success is absence of any tension and free drainage.

10.8.5.1 Procedure

The colon is reflected medially off the kidney and the dilated renal pelvis presents itself into view. Once the renal pelvis has been exposed, it is carefully freed from all its confusing coverings of connective tissue. When these have been swept aside, the relationship of the lower pole vessels if these are present becomes clear, and they are lifted up on a silicone sling (Figure 10.7).

If the lower pole vessels are in the way, a dismembered pyeloplasty will be performed, and this can be modified if there is a long narrow upper segment of ureter (Figure 10.8).

It helps to fill the renal pelvis with 30–40 ml of saline with a syringe before marking out the flap with fine stay‐sutures (Figure 10.9). Unless this is performed while the pelvis is distended, it is easy to mark it wrongly. Cut through the ureter near the pelviureteric junction, and thread it behind the lower pole vessels, slit up, and spatulate in the lateral aspect. The redundant renal pelvis is excised. The apex of the spatulated ureter is brought to the inferior border of the renal pelvis (Figure 10.10). It is important to use only absorbable suture material for the anastomosis, but whether interrupted or continuous sutures are used is of little consequence. A ureteral stent inserted through the anastomosis.

If there is a long narrow segment of ureter, the flap can be made longer by using the Culp manoeuvre, carrying the flap in a spiral fashion round the pelvis (Figure 10.11). If there is no lower pole vessel, there is no need to detach the ureter and either a simple flap or the Culp spiral modification can be adapted. Using either method, the anastomosis is made in a long ellipse to prevent subsequent contraction, and there must be no tension.

Other pyeloplasty procedures include Foley Y‐V Plasty and Scardino‐Prince vertical flap.

10.8.5.2 Results

Stones have been seen to form on the suture material used to sew the ureter to the renal pelvis; they are almost inevitable if nonabsorbable suture has been used for the anastomosis, but they can occur on absorbable sutures as well.

Hypertension is an important late sequel of even a successful pyeloplasty, and it is wise for the patient to be closely followed by the general practitioner.

In a few patients, despite an apparently successful operation – as judged by a free runoff down the anastomosis and no hold‐up of contrast or isotope in the renal pelvis – the patient continues to experience recurrent pain in the loin, sometimes accompanied by verified infection in the urine. To some extent this kind of result, which is fortunately rare, represents a failure of selection of candidates for an operation; in retrospect, it is easy to say that it would have been better to have advised a nephrectomy.

In the majority, the outcome is excellent in terms of the absence of symptoms, infection, stones, and deterioration of renal function, but when assessed by the appearance of the kidney in a urogram, the patient and the surgeon need to be warned that the kidney often continues to look disappointingly dilated. This does not mean that it is obstructed. An initial ultrasound or a MAG3 renogram can show whether there is worsening hydronephrosis. However, it does mean that once there has been a thinning of the renal parenchyma and a deterioration in the muscular capacity of the renal pelvis, then the pyelographic appearances are unlikely to return to normal. This need not matter; the important point is that the obstruction has been permanently overcome and things will not deteriorate any further.

10.8.6 Endopyelotomy

The basic principle of this technique is a full‐thickness postero‐lateral incision through the obstructed anatomy in the PUJ from lumen to periureteric and peripelvic fat with bridging ureteric stent placement to allow healing. Rarely offered as first‐line treatment for PUJ obstruction, however, can be in recurrence of PUJ obstruction post pyeloplasty rather than a repeated pyeloplasty. Can also be offered in the symptomatic frail elderly patient.

Ramsey first described the technique in 1984 [31]. Multiple adaptations have been made since. The incision can be done by either an endopyelotomy knife or laser through either percutaneous or ureteroscopic approaches. Success rates do not approach that of laparoscopic or robotic pyeloplasty but have been shown to be as high as 87.5% in well‐selected patients [32]. Antegrade (via percutaneous tract) and retrograde approaches have been described as well as retrograde cautery wire balloon endopyelotomy and balloon endodilatation. There is no convincing evidence that any of these methods have superior outcomes. The benefits include shorter operative time with reduced hospital stays and postoperative recovery.

10.8.7 Nephrectomy in Hydronephrosis

When the preoperative investigations show that the kidney has minimal function, or when at operation it is clear that the cortex is but a paperthin shell, nephrectomy is the correct operation.

10.10.1 Definitions and Incidences

Duplication implies that there is an upper and a lower renal function moiety, each with its own pelvicalyceal system and ureter. The individual moeity’s ureter may join anywhere along its length. Nearly 1% of postmortem examinations have been found to show upper urinary tract duplication to varying degrees [34]. Roughly 40% of cases show bilateral abnormalities. Duplication anomalies show an incomplete penetrance and are an autosomal dominant trait affecting 8% of member of affected families. The majority of upper tract duplications unite above the ureteric orifice and usually have minimal clinical manifestations. On the contrary, complete duplications often cause symptoms and affect renal functionality. These are much rarer affecting less than 0.1% of individuals, with the majority being female. Twenty‐five percent of complete duplications present bilaterally.

In incomplete ureteric duplication, the ureteric bud arises normally from the mesonephric duct but then undergoes variable degrees of bifurcation. Complete duplication occurs when two separate ureteric buds arise separately from the mesonephric duct. In complete duplication systems, inevitably the accessory ureteric bud drains the upper pole moiety and enters the bladder in a distal location more medially placed location than the lower moiety ureter (the Meyer‐Weigart law). This can lead the upper moiety to ectopic insertion, which may the urethra or the urogenital sinus. The ectopic ureter is prone to obstruction because of its long intramural course through the bladder wall, which can cause severe hydronephrosis. Upper moiety ureters are usually associated with dysplastic nonfunctioning upper renal moiety. In contrast, due to the insertion into the bladder with a shorter submucosal tunnel, VUR occurs predominantly in the lower moiety ureteric orifice (Figures 10.12–10.14).

Ectopic ureter is any ureter, single or duplex, that does not enter the trigonal area of the bladder. In females, the ectopic ureter may be suprasphincteric, at the level of the striated sphincter, or distal either at distal vagina or introitus. In contrast, male ectopic ureters are always suprasphincteric, connecting to the seminal vesicles, ejaculatory ducts, or the vas deferens, causing pain and infection rather than urinary incontinence clinically.

Ureteroceles are cystic dilatations of the distal ureter that are located either within the bladder or involving the bladder neck and urethra (Figure 10.15). These can also be single or duplex systems (usually in the ureter draining the upper pole moiety). There are several classifications of ureteroceles with the most clinically useful being intravesical (entire ureterocele above bladder neck) or extravesical (some part of ureterocele permanently at bladder neck or urethra).

10.10.2 Management

Treatment of ectopic ureter or ureterocele, whether of a single or duplex system, is based on anatomical and functional investigations.

Anatomical assessment involves an ultrasound. It will easily identify upper tract dilatation in both a single and duplex system, as well as help differentiate a dilated ectopic ureter from a ureterocele (Figure 10.15). A CTU or MRU can provide the most detailed imaging of an affected urinary tract.

Functional assessment of renal function can be made by DMSA scan or to investigate obstruction form upper moiety (Figure 10.14) and bladder assessment by voiding cystourethrogram (VCUG) (Figure 10.16). Endoscopic evaluation is essential. The goals of therapy are preservation of renal function, elimination of obstruction, infection and reflux, and maintenance of urinary continence.

Uncomplicated, asymptomatic duplex does not need treatment. Obstructed upper moiety will need a ureteric reimplantation. However, if the renal moiety is poorly functioning, a hemi‐nephrectomy and ureterectomy would be the treatment choice.

10.11.1 Aetiology

Primary anatomical VUR is a defect in the intramural ureteric length to ureteric diameter ratio (ILUD ratio), whereby the intramural ureteric length is too short to allow successfully complete compression to prevent reflux. Normal ratio is 5 : 1. See mainly in duplexed lower moiety ureters, but this can happen in single ureters.

Secondary VUR is due to disease or conditions not related to the intramural ureter:

• Most common cause is iatrogenic: during TURP or TURBT whereby the ureteric orifice is resected, reducing the ILUD ratio. Other causes include ureteric reimplantation without antireflux techniques or incising a ureterocoele open.
  
• High bladder pressure leading to significantly high bladder pressures, overcoming the physiological sphincter mechanism (e.g. bladder outflow obstruction [i.e. prostatic obstruction or urethral strictures] or poor bladder compliance (i.e. [neuropathic bladders]).

VUR is more commonly asymptomatic detected incidentally; however, patients can present with loin pain occurring with a full bladder or after micturition or recurrent UTIs.

Investigation of choice to demonstrate VUR is a voiding cystourethrogram. Voiding cystogram can establish the grade of VUR. which can help guide management (Table 10.7).

Urodynamics can be done to assess bladder pressures. CTU can be useful to establish anatomy. DMSA scan can be done to assess renal function and demonstrate renal scarring.

10.11.2 Management

Generally, VUR is not a dangerous or harmful condition; however, in the presence of high bladder pressure or infection, VUR can slowly kill the kidney. Ergo, treatment is tailored around the symptoms, renal functionality, as well as degree of VUR. VUR grades I–II resolve spontaneously in 80–90% of patients, whereas grade III in 50% and in 20% of grades IV and 10% of grade V [35].

10.11.3 Primary VUR

Conservative measures: with increased hydration and bladder toilet training, with the use of prophylactic antibiotics if there is a history of recurrent UTIs.

Endoscopic management: Deflux bulking agents can be injected intramurally with the distal ureter and ureteric orifice with high success rates. However, repeated injections might be required. Deflux is a hyaluronic acid/dextranomer copolymer.

10.11.4 Surgery

Ureteric reimplantation is indicated in higher grade VUR, or lower grade VUR failed to respond to endoscopic injections in a duplex renal system, or renal ectopia.

Nephroureterectomy if the kidney is nonfunctioning, or VUR is persistant and causing significant symptoms.

Treatment of secondary VUR is managing of the underlying pathology; if it fails, measures are similar to primary VUR managements.