**2. Anatomy of Vesicoureteric Junction (VUJ)**

The VUJ can be recognized as a small convex, bulging-out structure on the mucosal surface of the urinary bladder. The function of the VUJ is to allow unhindered antegrade passage of urine bolus from ureter into the bladder while prevent the reflux of urine into the ureter from the bladder, during both normal bladder filling and voiding.

### **2.1. Histology and histochemical study of the VUJ**

The anatomical studies of human VUJ were first started around year 1800. To date, the mechanism of how VUJ functions is still poorly understood and controversies exist among different theories.

The generally accepted anatomical presentation of the VUJ is illustrated in a diagrammatic form as follows: (Fig 1).

© 2013 Leung and Chu; licensee InTech. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2013 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

internal layer originate behind the ureteric orifice. The outer longitudinal bundles continue with the capsules of adjacent pelvic organs and the pubovesical ligament (Noordzij & Dab‐ hoiwala, 1993). Three muscle layers of the detrusor form the superior part or roof of the VUJ. The inferior part or the floor is formed by only two layers of detrusor. They are the outer longitudinal layer (sling muscle) and the inner circular layer (sling fascia). They play an important role in the physiology of the VUJ by providing a firm support to the structures of the intravesical ureter and preventing reflux. They also form part of the trigone (Hutch et

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Finally the innermost mucosal layer of the ureter and the urinary bladder consists of a tran‐ sitional epithelium (also known as the urothelium) and the lamina propria, the underlying supportive layer, consists of loose connective tissue. The urothelium is usually extensively folded, giving the ureteric lumen a satellite outline in histological specimens. However, this satellite pattern is not readily seen with ultrasound and may reflect a different process of

The gap in the bladder wall through which the ureter passes is known as the ureteric hiatus. There are two gaps: outer and the inner hiatus. The outer hiatus is slightly higher and lateral to the inner hiatus. A roof and floor can also be identified. Thus the lower end of the ureter becomes oblique in position as it pierces through the bladder wall. The diagonal angle of passage of the ureter through the bladder wall in eight fresh human cadavers was 110 when using the endoluminal ultrasound method (Roshani et al., 1999). This cannot be confirmed in vivo because the angle of entry is only noticeable near the VUJ where the intramural

There are two portions of ureter: The part outside the bladder muscle is known as the juxta‐ vesical portion while inside is known as the intravesical portion. At birth, the intravesical ureter is 0.5 cm in length while in adulthood it is 1.5 to 2.6 cm. The intravesical ureter has two parts: the intramural and submucosal portion. The submucosal portion is covered by mucous membrane only. The intramural portion measures 0.9 cm while the submucosal part measures 0.7 cm in length. They are of approximately equal length in 80% at all ages (Cus‐

There is an additional group of looser muscle fibers closely related to the adventitia of the intra‐ vesical and juxtavesical ureter, which is known as the ureteric sheath. This connective tissue sleeve separates the ureteric muscle coat from the bladder wall. However, the origin of this sheath is of great dispute. Some studies have suggested that the ureteric sheath is a separable structure. It is ureteric in origin and made by a fibromuscular layer wrapped around the intra‐ mural ureter (Disse, 1902; Tanagho & Pugh, 1963; Tanagho et al., 1968; Versari, 1908). Other studies have suggested that the sheath is vesical in origin, which is composed of longitudinal muscle fibers ascending from the bladder onto the juxtavesical part of the ureter (Hutch et al.,

sen, 1967; Gruber, 1929; Hutch, 1961; Roshani et al., 1999; Tanagho & Pugh, 1963).

1961; Noordzij & Dabhoiwala, 1993; Uhlenhuth et al., 1953; Waldeyer, 1892).

.

collapse of the urothelium in vivo (Dyson, 1995; Motola et al., 1988; Tanagho, 2000).

channel is around 4-5 mm and more sharply angled than 110

al., 1961; Tanagho & Pugh, 1963).

*Different portion of the VUJ (Fig 1b)*

*Ureteric Sheath (Fig. 1a)*

*Ureteric hiatus*

**Figure 1.** Schematic diagram of the anatomical layers in (a) ureteric and urinary bladder wall and (b) VUJ in human

### *2.1.1. Histology of the VUJ*

VUJ involves three anatomical components: the ureteric wall, urinary bladder wall and the ureteric sheath. They are described as follows:

### *Three layers of ureteric and urinary bladder wall (Fig. 1a)*

The wall of the ureter and urinary bladder consists of three layers: the outer adventitia, mid‐ dle muscular layer and the inner mucosal layer.

The adventitia is the outermost layer composes of mainly fibrous connective tissues.

The muscular layer of the ureter consists of non-striated muscle which is uniform in thick‐ ness. When approaching the VUJ the muscle coat composes predominately longitudinally orientated muscle bundles (Gearhart et al., 1993). The ureteric muscle then fans out with fi‐ bers splitting around the orifice before becoming part of the superficial trigone. Some of the fibers extend to the urethra thereby creating connection between the urethra and the ureter (Bell's muscle) (Gearhart et al., 1993; Hutch et al., 1961; Juskiewenski et al., 1984; Noordzij & Dabhoiwala, 1993; Roshani et al., 1996; Stephens & Lenaghan, 1962; Tanagho & Pugh, 1963; Tanagho et al.,1968).

The muscular layer of the urinary bladder is also known as the detrusor muscle. It is composed of interlacing large bundles of non-striated muscle cell in a criss-cross arrangement. Different regions of the bladder have different muscle arrangements. There are anastomoses between different muscles in the form of complex reticular or netlike muscular meshwork. Four regions can be identified: the detrusor muscle proper, trigone, VUJ and the bladder neck.

The detrusor muscle proper consists of three ill-defined layers: an inner longitudinally ori‐ entated layer of muscle bundles, a substantial middle circular layer and an outer longitudi‐ nally orientated layer (Hunter, 1954; Uhlenhuth et al., 1953). The muscle fibers of the internal layer originate behind the ureteric orifice. The outer longitudinal bundles continue with the capsules of adjacent pelvic organs and the pubovesical ligament (Noordzij & Dab‐ hoiwala, 1993). Three muscle layers of the detrusor form the superior part or roof of the VUJ. The inferior part or the floor is formed by only two layers of detrusor. They are the outer longitudinal layer (sling muscle) and the inner circular layer (sling fascia). They play an important role in the physiology of the VUJ by providing a firm support to the structures of the intravesical ureter and preventing reflux. They also form part of the trigone (Hutch et al., 1961; Tanagho & Pugh, 1963).

Finally the innermost mucosal layer of the ureter and the urinary bladder consists of a tran‐ sitional epithelium (also known as the urothelium) and the lamina propria, the underlying supportive layer, consists of loose connective tissue. The urothelium is usually extensively folded, giving the ureteric lumen a satellite outline in histological specimens. However, this satellite pattern is not readily seen with ultrasound and may reflect a different process of collapse of the urothelium in vivo (Dyson, 1995; Motola et al., 1988; Tanagho, 2000).

### *Ureteric hiatus*

**Figure 1.** Schematic diagram of the anatomical layers in (a) ureteric and urinary bladder wall and (b) VUJ in human

VUJ involves three anatomical components: the ureteric wall, urinary bladder wall and the

The wall of the ureter and urinary bladder consists of three layers: the outer adventitia, mid‐

The muscular layer of the ureter consists of non-striated muscle which is uniform in thick‐ ness. When approaching the VUJ the muscle coat composes predominately longitudinally orientated muscle bundles (Gearhart et al., 1993). The ureteric muscle then fans out with fi‐ bers splitting around the orifice before becoming part of the superficial trigone. Some of the fibers extend to the urethra thereby creating connection between the urethra and the ureter (Bell's muscle) (Gearhart et al., 1993; Hutch et al., 1961; Juskiewenski et al., 1984; Noordzij & Dabhoiwala, 1993; Roshani et al., 1996; Stephens & Lenaghan, 1962; Tanagho & Pugh, 1963;

The muscular layer of the urinary bladder is also known as the detrusor muscle. It is composed of interlacing large bundles of non-striated muscle cell in a criss-cross arrangement. Different regions of the bladder have different muscle arrangements. There are anastomoses between different muscles in the form of complex reticular or netlike muscular meshwork. Four regions

The detrusor muscle proper consists of three ill-defined layers: an inner longitudinally ori‐ entated layer of muscle bundles, a substantial middle circular layer and an outer longitudi‐ nally orientated layer (Hunter, 1954; Uhlenhuth et al., 1953). The muscle fibers of the

can be identified: the detrusor muscle proper, trigone, VUJ and the bladder neck.

The adventitia is the outermost layer composes of mainly fibrous connective tissues.

*2.1.1. Histology of the VUJ*

Tanagho et al.,1968).

ureteric sheath. They are described as follows:

110 Recent Advances in the Field of Urinary Tract Infections

dle muscular layer and the inner mucosal layer.

*Three layers of ureteric and urinary bladder wall (Fig. 1a)*

The gap in the bladder wall through which the ureter passes is known as the ureteric hiatus. There are two gaps: outer and the inner hiatus. The outer hiatus is slightly higher and lateral to the inner hiatus. A roof and floor can also be identified. Thus the lower end of the ureter becomes oblique in position as it pierces through the bladder wall. The diagonal angle of passage of the ureter through the bladder wall in eight fresh human cadavers was 110 when using the endoluminal ultrasound method (Roshani et al., 1999). This cannot be confirmed in vivo because the angle of entry is only noticeable near the VUJ where the intramural channel is around 4-5 mm and more sharply angled than 110 .

### *Different portion of the VUJ (Fig 1b)*

There are two portions of ureter: The part outside the bladder muscle is known as the juxta‐ vesical portion while inside is known as the intravesical portion. At birth, the intravesical ureter is 0.5 cm in length while in adulthood it is 1.5 to 2.6 cm. The intravesical ureter has two parts: the intramural and submucosal portion. The submucosal portion is covered by mucous membrane only. The intramural portion measures 0.9 cm while the submucosal part measures 0.7 cm in length. They are of approximately equal length in 80% at all ages (Cus‐ sen, 1967; Gruber, 1929; Hutch, 1961; Roshani et al., 1999; Tanagho & Pugh, 1963).

### *Ureteric Sheath (Fig. 1a)*

There is an additional group of looser muscle fibers closely related to the adventitia of the intra‐ vesical and juxtavesical ureter, which is known as the ureteric sheath. This connective tissue sleeve separates the ureteric muscle coat from the bladder wall. However, the origin of this sheath is of great dispute. Some studies have suggested that the ureteric sheath is a separable structure. It is ureteric in origin and made by a fibromuscular layer wrapped around the intra‐ mural ureter (Disse, 1902; Tanagho & Pugh, 1963; Tanagho et al., 1968; Versari, 1908). Other studies have suggested that the sheath is vesical in origin, which is composed of longitudinal muscle fibers ascending from the bladder onto the juxtavesical part of the ureter (Hutch et al., 1961; Noordzij & Dabhoiwala, 1993; Uhlenhuth et al., 1953; Waldeyer, 1892).

Elbadawi and Ruotolo supported the dual sheath concept. They found two muscular sheaths surrounding the distal end of the ureter, superficial and deep periureteric sheaths. The superficial one was vesical in origin and the deep one was both ureteric and vesical in origin (Elbadawi, 1972; Ruotolo, 1949).

Both Jen and Roshani have shown that detrusor and deep trigone receive cholinergic inner‐ vation while the ureteric and superficial trigonal muscles receive noradrenergic innervation

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(Jen et al., 1995; Roshani et al., 1996) (Fig 2).

**Figure 2.** Histochemical study of the VUJ in human (according to Gearhart et al., 1993)

muscle and is rich in AChE (Gearhart et al., 1993).

**2.2. Anti-reflux mechanism at VUJ**

valvular action is controversial.

*2.2.1. Passive valve mechanism*

Gearhart have found three distinct smooth muscle components in the VUJ. The innermost layer is the ureteric muscle which is rich in pseudocholinesterase (PChE) and this muscle fans out and continues with the trigonal fiber. The intermediate layer of muscle is a distinct layer rich in both acetylcholinesterase (AChE) and PChE. It is not derived from the ureter or the detrusor but it continues with the trigonal fiber. The outermost layer is the detrusor

These additional informations further support our hypothesis that VUJ is likely to possess

There are three well known schools of though for the anti-reflux mechanism: passive valve mechanism, mixed active and passive valvular action and sphincteric mechanism. However the exact nature of the anti-reflux mechanism of VUJ is unresolved and the existence of a

Passive valve mechanism is a purely passive one which depends on the length and obliquity of the intravesicular ureter. When the intravesical pressure increases during bladder filling or

functional active sphincteric mechanism rather than just a passive flap valve.

### *Other areas of the VUJ*

There are also other areas about VUJ that are in dispute, including whether there is direct continuation of the trigone with ureter and the number of layers in trigonal muscle.

Some studies have suggested that the trigone is direct continuation with the ureter. The muscle fibers of the intravesical ureter fan out and become continuous with the superficial trigonal muscle. On the other hand, the ureteric sheath also fans out and joins the muscle bundles from the contralateral ureter forming the middle or deep trigone and extended to the urethra. This is called the Bell's muscle (Gruber, 1929; Juskiewenski et al., 1984; Noordzij & Dabhoiwala, 1993; Roshani et al., 1996; Tanagho & Pugh, 1963; Tanagho et al., 1968).

However, Disse, Uhlenhuth found that the ureteric muscle stopped abruptly in the VUJ thus they has proposed that the trigonal muscle is not of ureteric origin but represents submu‐ cous musculature (Disse, 1902; Uhlenhuth et al., 1953).

There is an isolated report on the existence of a sling muscle and meatal muscle in the VUJ (Fig 1a). Hutch has reported the existence of the sling muscle and sling fascia. They are the outer longitudinal and inner circular bladder muscles that form the floor of the VUJ and are thin but tough strip of muscle. These muscles lie underneath and provide firm support to the intravesical ureter, whichmight play a role in preventing reflux (Hutch et al., 1961).

Both Zaffagnini and Korner have reported the existence of the meatal muscle. There are transureteric vesical muscle bundles and extension of the deep periureteric sheath superfi‐ cial to the ureteric muscle in the roof of the submucosal segment. The bundles of the two periureteric sheaths are cross or decussate with each other in the roof of the submucosal seg‐ ment. This has been described as the meatal muscle (Zaffagnini & Mangiaracina, 1955) or a double perimeatal muscular sling (Korner, 1962).

Despite the controversies in different studies about the origin and relationships of the mus‐ cles, all studies do support the presence of muscle in the VUJ, thus suggesting that a poten‐ tial functional muscular sphincter might be present.

### *2.1.2. Histochemical study of the VUJ*

The VUJ has a dual sympathetic-parasympathetic innervation. It is richly supplied by nora‐ drenergic and cholinergic nerves (Dixon et al., 1992, 1994, 1998a, 1998b; Gearhart et al., 1993; Gosling et al., 1999). The nerves supplying the ureterotrigonal and vesical component of the VUJ have the same origin: the ureterovesical ganglion complex. Therefore, theoretically the activity of the two components can be synchronized and regulated in relation to each other (Elbadawi & Schenk, 1971).

Both Jen and Roshani have shown that detrusor and deep trigone receive cholinergic inner‐ vation while the ureteric and superficial trigonal muscles receive noradrenergic innervation (Jen et al., 1995; Roshani et al., 1996) (Fig 2).

**Figure 2.** Histochemical study of the VUJ in human (according to Gearhart et al., 1993)

Gearhart have found three distinct smooth muscle components in the VUJ. The innermost layer is the ureteric muscle which is rich in pseudocholinesterase (PChE) and this muscle fans out and continues with the trigonal fiber. The intermediate layer of muscle is a distinct layer rich in both acetylcholinesterase (AChE) and PChE. It is not derived from the ureter or the detrusor but it continues with the trigonal fiber. The outermost layer is the detrusor muscle and is rich in AChE (Gearhart et al., 1993).

These additional informations further support our hypothesis that VUJ is likely to possess functional active sphincteric mechanism rather than just a passive flap valve.

### **2.2. Anti-reflux mechanism at VUJ**

Elbadawi and Ruotolo supported the dual sheath concept. They found two muscular sheaths surrounding the distal end of the ureter, superficial and deep periureteric sheaths. The superficial one was vesical in origin and the deep one was both ureteric and vesical in

There are also other areas about VUJ that are in dispute, including whether there is direct

Some studies have suggested that the trigone is direct continuation with the ureter. The muscle fibers of the intravesical ureter fan out and become continuous with the superficial trigonal muscle. On the other hand, the ureteric sheath also fans out and joins the muscle bundles from the contralateral ureter forming the middle or deep trigone and extended to the urethra. This is called the Bell's muscle (Gruber, 1929; Juskiewenski et al., 1984; Noordzij & Dabhoiwala, 1993; Roshani et al., 1996; Tanagho & Pugh, 1963; Tanagho et al., 1968).

However, Disse, Uhlenhuth found that the ureteric muscle stopped abruptly in the VUJ thus they has proposed that the trigonal muscle is not of ureteric origin but represents submu‐

There is an isolated report on the existence of a sling muscle and meatal muscle in the VUJ (Fig 1a). Hutch has reported the existence of the sling muscle and sling fascia. They are the outer longitudinal and inner circular bladder muscles that form the floor of the VUJ and are thin but tough strip of muscle. These muscles lie underneath and provide firm support to the intravesical ureter, whichmight play a role in preventing reflux (Hutch et al., 1961).

Both Zaffagnini and Korner have reported the existence of the meatal muscle. There are transureteric vesical muscle bundles and extension of the deep periureteric sheath superfi‐ cial to the ureteric muscle in the roof of the submucosal segment. The bundles of the two periureteric sheaths are cross or decussate with each other in the roof of the submucosal seg‐ ment. This has been described as the meatal muscle (Zaffagnini & Mangiaracina, 1955) or a

Despite the controversies in different studies about the origin and relationships of the mus‐ cles, all studies do support the presence of muscle in the VUJ, thus suggesting that a poten‐

The VUJ has a dual sympathetic-parasympathetic innervation. It is richly supplied by nora‐ drenergic and cholinergic nerves (Dixon et al., 1992, 1994, 1998a, 1998b; Gearhart et al., 1993; Gosling et al., 1999). The nerves supplying the ureterotrigonal and vesical component of the VUJ have the same origin: the ureterovesical ganglion complex. Therefore, theoretically the activity of the two components can be synchronized and regulated in relation to each other

continuation of the trigone with ureter and the number of layers in trigonal muscle.

origin (Elbadawi, 1972; Ruotolo, 1949).

112 Recent Advances in the Field of Urinary Tract Infections

cous musculature (Disse, 1902; Uhlenhuth et al., 1953).

double perimeatal muscular sling (Korner, 1962).

tial functional muscular sphincter might be present.

*2.1.2. Histochemical study of the VUJ*

(Elbadawi & Schenk, 1971).

*Other areas of the VUJ*

There are three well known schools of though for the anti-reflux mechanism: passive valve mechanism, mixed active and passive valvular action and sphincteric mechanism. However the exact nature of the anti-reflux mechanism of VUJ is unresolved and the existence of a valvular action is controversial.

### *2.2.1. Passive valve mechanism*

Passive valve mechanism is a purely passive one which depends on the length and obliquity of the intravesicular ureter. When the intravesical pressure increases during bladder filling or voiding, there is an increase in length of the intravesical ureter and a one way "flap-valve" at the ureteric orifice is produced. The ureter is then compressed and flattened thus preventing regurgitation (Hutch, 1952; Hutch et al., 1955; Juskiewenski et al., 1984; Paquin, 1959).

Ureteric jet can be further characterized by its pulse wave Doppler waveform. In the next section, detailed literature review on ureteric jet in both human and animal studies will be

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Ureteric jet has been reported as early as 1955 (Kalmon et al., 1955) using the X-ray method (in‐ travenous urography, IVU) while the first one to document the sonographic appearance of jet was Dubbins (Dubbins et al., 1981). The reported incidence of the visualization of jet ranged from 5.7% to 100% (Blomley et al., 1997; Cox et al., 1992; Eklöf & Johanson, 1980; Elejalde& de Elejalde, 1983; Gothlin, 1964; Marshall et al., 1990; Nevin et al., 1962). There is a higher chance of visualizing jet using ultrasound than radiography. Recently, the reported rate of visualization

There are a number of theories why ureteric jet can be visualized on ultrasound, as follows: i) miniature bubbles produced in a rapidly moving fluid (Kremkau et al., 1970), ii) turbulent flow of urine into a static fluid in the closed bladder and the continual changes in the shear forces be‐ tween the jet and the adjacent static urine was the caused for the Doppler signal (Dubbins et al., 1981), iii) difference in specific gravities of the injected fluid and the fluid within the bladder (Kremer et al., 1982), iv) differences in density and compressibility changes between urine in

There are many descriptions about Doppler waveform such as crescendo and decrescendo forms, single-hump and multiple-hump (as many as four) curves, turbulent form of jet pat‐ tern, discrete jets, ureteric streaming, rest periods (ie, period of undetected flow). Jet pattern could be divided into three phases: Firstly, initial phase can be visualized as pulsed oozing or flattened type or combination of both. It is then followed by a steady phase as uniform Doppler waveforms at regular intervals and a final phase as uneven waveforms at irregular intervals (Cox et al., 1992; Jequier et al., 1990; Wu et al., 1995). The pattern of jet alters with physiological changes. After large fluid load, there is eitheris an increase in jet frequency or the pattern is converted to an almost continuous signal with absent humps (Jequier et al., 1990). This temporal variation also occurs in velocity, duration and amplitude of the jet

On the contrary, during inadequate hydration or in diseased patients, the waveform be‐

Jets are usually directed anteriorly, anteromedially, with or without crossing of the jets. Sometimes they can also be perpendicular to the mucosal surface. There is not much differ‐ ence in the jet direction bewteenboth paediatric and adult groups (Burge et al., 1991; Catala‐ no et al., 1998; Cox et al., 1992; Dubbins et al., 1981; Elejalde & de Elejalde, 1983; Jequier et

of ureteric jet in 1341 normal subjects using ultrasound is 99% (Leung et al., 2007b).

bladder and in the ureter (Baker & Middleton, 1992; Price et al., 1989).

(Blomley et al., 1997; Burge et al., 1991; Cox et al., 1992; Wu et al., 1995).

outlined.

**3.2. Previous work on the ureteric jet in human**

*3.2.1. Characteristics of ureteric jet*

comes flattened (Wu et al., 1955).

al., 1990; Patel & Kellett, 1996; Sweet et al., 1995).

*Pattern of the jet*

### *2.2.2. Mixed active and passive valvular action*

In this theory, the anti-reflux action depends on both the sphincter action of the bladder muscle and the obliquity of the ureter. The anti-reflux mechanism is brought by the dynamic relationship between bladder wall, intravesical ureter and trigone. (Blok et al., 1985, 1986; Hutch, 1952; Hutch et al., 1955, 1961; Roshani et al., 2000a, 2000b; Tanagho & Pugh, 1963; Tanagho et al.,1968).

### *2.2.3. Sphincteric mechanism*

In this theory, the integrity of the VUJ is based on the sphincter action produced by the ure‐ teric function and tone, and or urinary bladder action alone. The sphincteric action is brought by the muscular activity of the ureteric muscle, sling muscle, sling fascia and the Waldeyer's sheath and the intricate muscular meshwork of the trigonal region of the blad‐ der (Hutch et al., 1961; Noordzij & Dabhoiwala, 1993; Stephens & Lenaghan, 1962; Stewart JC 1937; Tanagho & Pugh, 1963; Tanagho et al., 1968; Uhlenhuth et al., 1953).

### **3. Review of previous studies on ureteric jet**

### **3.1. What is ureteric jet?**

Ureteric jet is the forceful ejection of urine through the VUJ into the bladder and it can be detected by gray scale as a stream or burst of low-intensity echoes emerging from the ureter‐ ic orifice. The jet lasts for few seconds and it is fast enough to produce a frequency shift; thus both colour and Doppler waveform can be obtained at real-time (Fig 3)

**Figure 3.** Colour and Doppler waveform of the ureteric jet.

Ureteric jet can be further characterized by its pulse wave Doppler waveform. In the next section, detailed literature review on ureteric jet in both human and animal studies will be outlined.

### **3.2. Previous work on the ureteric jet in human**

Ureteric jet has been reported as early as 1955 (Kalmon et al., 1955) using the X-ray method (in‐ travenous urography, IVU) while the first one to document the sonographic appearance of jet was Dubbins (Dubbins et al., 1981). The reported incidence of the visualization of jet ranged from 5.7% to 100% (Blomley et al., 1997; Cox et al., 1992; Eklöf & Johanson, 1980; Elejalde& de Elejalde, 1983; Gothlin, 1964; Marshall et al., 1990; Nevin et al., 1962). There is a higher chance of visualizing jet using ultrasound than radiography. Recently, the reported rate of visualization of ureteric jet in 1341 normal subjects using ultrasound is 99% (Leung et al., 2007b).

There are a number of theories why ureteric jet can be visualized on ultrasound, as follows: i) miniature bubbles produced in a rapidly moving fluid (Kremkau et al., 1970), ii) turbulent flow of urine into a static fluid in the closed bladder and the continual changes in the shear forces be‐ tween the jet and the adjacent static urine was the caused for the Doppler signal (Dubbins et al., 1981), iii) difference in specific gravities of the injected fluid and the fluid within the bladder (Kremer et al., 1982), iv) differences in density and compressibility changes between urine in bladder and in the ureter (Baker & Middleton, 1992; Price et al., 1989).

### *3.2.1. Characteristics of ureteric jet*

### *Pattern of the jet*

voiding, there is an increase in length of the intravesical ureter and a one way "flap-valve" at the ureteric orifice is produced. The ureter is then compressed and flattened thus preventing

In this theory, the anti-reflux action depends on both the sphincter action of the bladder muscle and the obliquity of the ureter. The anti-reflux mechanism is brought by the dynamic relationship between bladder wall, intravesical ureter and trigone. (Blok et al., 1985, 1986; Hutch, 1952; Hutch et al., 1955, 1961; Roshani et al., 2000a, 2000b; Tanagho & Pugh, 1963;

In this theory, the integrity of the VUJ is based on the sphincter action produced by the ure‐ teric function and tone, and or urinary bladder action alone. The sphincteric action is brought by the muscular activity of the ureteric muscle, sling muscle, sling fascia and the Waldeyer's sheath and the intricate muscular meshwork of the trigonal region of the blad‐ der (Hutch et al., 1961; Noordzij & Dabhoiwala, 1993; Stephens & Lenaghan, 1962; Stewart

Ureteric jet is the forceful ejection of urine through the VUJ into the bladder and it can be detected by gray scale as a stream or burst of low-intensity echoes emerging from the ureter‐ ic orifice. The jet lasts for few seconds and it is fast enough to produce a frequency shift;

JC 1937; Tanagho & Pugh, 1963; Tanagho et al., 1968; Uhlenhuth et al., 1953).

thus both colour and Doppler waveform can be obtained at real-time (Fig 3)

**3. Review of previous studies on ureteric jet**

**Figure 3.** Colour and Doppler waveform of the ureteric jet.

regurgitation (Hutch, 1952; Hutch et al., 1955; Juskiewenski et al., 1984; Paquin, 1959).

*2.2.2. Mixed active and passive valvular action*

114 Recent Advances in the Field of Urinary Tract Infections

Tanagho et al.,1968).

*2.2.3. Sphincteric mechanism*

**3.1. What is ureteric jet?**

There are many descriptions about Doppler waveform such as crescendo and decrescendo forms, single-hump and multiple-hump (as many as four) curves, turbulent form of jet pat‐ tern, discrete jets, ureteric streaming, rest periods (ie, period of undetected flow). Jet pattern could be divided into three phases: Firstly, initial phase can be visualized as pulsed oozing or flattened type or combination of both. It is then followed by a steady phase as uniform Doppler waveforms at regular intervals and a final phase as uneven waveforms at irregular intervals (Cox et al., 1992; Jequier et al., 1990; Wu et al., 1995). The pattern of jet alters with physiological changes. After large fluid load, there is eitheris an increase in jet frequency or the pattern is converted to an almost continuous signal with absent humps (Jequier et al., 1990). This temporal variation also occurs in velocity, duration and amplitude of the jet (Blomley et al., 1997; Burge et al., 1991; Cox et al., 1992; Wu et al., 1995).

On the contrary, during inadequate hydration or in diseased patients, the waveform be‐ comes flattened (Wu et al., 1955).

Jets are usually directed anteriorly, anteromedially, with or without crossing of the jets. Sometimes they can also be perpendicular to the mucosal surface. There is not much differ‐ ence in the jet direction bewteenboth paediatric and adult groups (Burge et al., 1991; Catala‐ no et al., 1998; Cox et al., 1992; Dubbins et al., 1981; Elejalde & de Elejalde, 1983; Jequier et al., 1990; Patel & Kellett, 1996; Sweet et al., 1995).

### *Parameters of the jet*

The extension of jet varies from 1 to 5 cm into the bladder but sometimes extended more than 5 cm or less than 1 cm (Dubbins et al., 1981; Elejalde & de Elejalde, 1983; Kremer et al., 1982).

In our institution, we have also studied the ureteric jet in 16s female pigs at the age of two to three monthsserially. The first scan was the baseline study, after that the pig underwent the process of deroofing of the intravesical portion on one of the ureters. The second scan was done one month after deroofing. The third scan was done when the pigs were four to five months old. The data from the pigs was compared with a group of 31 girls up to four years old. In this study, the incidence of monphasic waveform does not decrease as the pigs be‐

Functional Anatomy of the Vesicoureteric Junction: Implication on the Management of VUR/ UTI

http://dx.doi.org/10.5772/52168

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This observation is quite different from that in the human studies, as discussed in laterl part

Ureteric jets areclassified according to the number of peaks within that particular Doppler waveform. Six basic patterns are identified: monophasic (with only one peak), biphasic (two peaks), triphasic (three peaks), polyphasic (number of peaks exceeding three), "square" (a plateau waveform in which no distinct peak be identified but of average duration); and "continuous" when the waveform lasts longer than 20 seconds which can be either polypha‐ sic or plateau form. These waveforms are further classified as three categories. Monophasic

The bi, tri- and polyphasic patterns are classified as the complex and mature pattern (Fig 5).

The last two patterns are the square and continuous forms. These are modified waveform

under the state of forced diuresis. They are classified as the diuretic pattern (Fig. 6).

jet is classifies as the first category of simple and immature pattern (Fig. 4).

**Figure 4.** The simple, immature monophasic pattern of the ureteric jet

come mature. There is no association between reflux and monophasic waveform.

of this chapter.

**4. Doppler waveform of ureteric jet**

**4.1. Pattern of the ureteric jet**

The mean jet velocity in the paediatric group varies between 18 to 31.6 cm/s (from 26 days to 17 years old) while in the adults it varies from 32.1 to 60 cm/s (from 18 to 49 years old (Cox et al., 1992; Jequier et al., 1990; Marshall, 1990; Matsuda et al., 1995; Matsuda& Saitoh, 1995; Sperandeo et al., 1994;). The duration of jet ranges from 0.6 to 7.5 s (Jequier et al., 1990) in paediatric and from 3.5 to 15 s in adult (Catalano et al., 1998; Cox et al., 1992; Kremer et al., 1982; Matsuda et al., 1995). The frequency of jet ranges from 2.4 to 5.4 jets/min in adult (Burge et al., 1991; Catalano et al., 1998; Kremer et al., 1982; Matsuda & Saitoh, 1995). The interjet interval ranges from 2 to 150 seconds (Catalano et al., 1998; Cox et al., 1992).

Adult subjects have a higher velocity (20 vs. 16 cm/s), duration (2.5 vs. 1.8 s) and frequency (1.2 vs1 jets/min) than children (Matsuda & Saitoh., 1995).

There is symmetry in jet frequency, jet parameters of velocity and duration between right and left side in healthy subjects (Burge et al., 1991; Cox et al., 1992; Matsuda & Saitoh, 1995).

Under the condition of forced diuresis, the jet hasa higher velocity (32.1 vs. 20 cm/s), dura‐ tion (6.7 vs. 2.5 s) and frequency (2.4 vs. 1.2 jets/min) than in the normal physiological state (Matsuda & Saitoh, 1995).

### *3.2.2. Clinical implication of ureteric jet*

It has previously been suggested that the presence of ureteric jet implies concurrenturinary tract infection (UTI) (Kalmon et al., 1955; Nevin et al., 1962) and absence of vesicoureteric reflux (VUR) (Kuhns, 1977). Subsequent studies prove that the presence of ureteric jet is just a normal physiologic phenomenon and cannot be used to diagnosis UTI or exclude VUR (Eklöf & Johan‐ son, 1980; Gothlin, 1964; Gudinchet et al., 1997; Jequier et al., 1990; Marshall et al., 1990).

However, the presence of jet could be used to exclude ureteric obstruction. The complete ab‐ sence of jet or a continuous low-level waveform is diagnostic for high-grade obstruction from ureteric calculi (Abulafia et al., 1997; Burge et al., 1991; Catalano et al., 1998; Elejalde & de Elejalde, 1983; Laing et al., 1994; Tal et al., 1994; Timor-Tritsch et al., 1997; Wu et al., 1995; Yoon et al., 2000).The difference in jet velocity has been used to study the effect of drug treatment on benign prostatic hyperplasia (Sperandeo et al., 1994, 1996) and to study the physiology of the kidney and ureter, includingthe glomerular filtration rate (Blomley et al., 1997; Burke & Washowich, 1998; Chiu et al., 1999; Han et al., 1996, 1997; Patel et al., 1996; Summers et al., 1992; Wachsberg, 1998)

### **3.3. Previous work on the ureteric jet on animals**

Lamb et al has found that ureteric jet can be consistently visualized in the dogs. The ureteric jets show variable frequency and duration. Lamb has suggested that the non-visualization of the ureteric jet might be helpful in diagnosing ectopic ureter (Lamb & Gregory, 1994).

In our institution, we have also studied the ureteric jet in 16s female pigs at the age of two to three monthsserially. The first scan was the baseline study, after that the pig underwent the process of deroofing of the intravesical portion on one of the ureters. The second scan was done one month after deroofing. The third scan was done when the pigs were four to five months old. The data from the pigs was compared with a group of 31 girls up to four years old. In this study, the incidence of monphasic waveform does not decrease as the pigs be‐ come mature. There is no association between reflux and monophasic waveform.

This observation is quite different from that in the human studies, as discussed in laterl part of this chapter.
