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Appearance of abdominal wall in prune belly syndrome
Tuesday, April 27, 2021
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|RENAL HANDLING OF CALCIUM AND PHOSPHATE|
|MODEL OF THE COUNTERCURRENT MULTIPLIER: PART I|
Tuesday, March 9, 2021
Cystoscopy refers to the direct visualization of the anterior and posterior urethra, bladder neck, and bladder mucosa using an endoscope. This procedure is performed both to evaluate the lower urinary tract and to establish access to the upper urinary tract (see Plate 10-33). Common indications include microscopic or gross hematuria, obstructive voiding symptoms, surveillance of a known urinary tract malignancy, inability to urinate following surgery for incontinence, and removal of a foreign body.
Cystoscopes are available in a variety of sizes and may be either rigid or ﬂexible in design. The size (outer diameter) of a cystoscope is given in the French scale. Rigid Cystoscopes. A rigid cystoscope has a long metal sheath, bridge, and rod-lens system. The sheath is the outer cover through which the rod-lens system is inserted. It remains within the bladder when the rod-lens system must be removed or exchanged. It also contains the port for infusion of irrigant ﬂuid, which helps maintain continuous visualization. The sheath is inserted into the bladder with an obturator in its lumen, which has an atraumatic tip to ensure safe passage through the urethra. “Visual” obturators contain a lumen for the lens, which permits direct visualization of the insertion process, whereas “nonvisual” obturators lack such a lumen.
Reconstruction of the ureter is required if a segment has been removed during the treatment of trauma, stricture, stenosis, or other regional disease. Several different techniques are available, with the optimal choice depending on both the location and length of the excised segment.
DISTAL URETERAL DEFECTS
Ureteroneocystostomy is appropriate for small defects (<5 cm) in the distal ureter. It consists of reimplantation of the proximal ureteral end directly into the bladder (see Plate 10-35). The reimplantation should be performed with antireﬂux technique whenever possible; however, if the ureter end is not long enough to pass through a new submucosal tunnel, a reﬂuxing oriﬁce may be created instead.
A psoas hitch can be used to bridge a longer defect (up to 10 cm) in the distal ureter. This procedure involves mobilization of the entire bladder. The contralateral superior umbilical artery, and in some cases the entire contralateral bladder pedicle, may be ligated to permit such mobilization. An anterior cystotomy is performed, and the dome of the bladder is sutured to the psoas muscle on the side of the ureteral injury. Care must be taken not to injure the femoral or genitofemoral nerves. The ureteral end is then reimplanted into the bladder using antireﬂux technique when possible.
A Boari ﬂap is reserved for more extensive defects in the mid and distal ureter (10 to 15 cm) that cannot be corrected with a psoas hitch. The bladder is mobilized as in a psoas hitch, and then a full-thickness ﬂap is created from the bladder wall in the territory of the superior vesical artery or one of its branches. The width of the ﬂap base should be at least three times greater than the length of the ﬂap to ensure an adequate vascular supply. The ﬂap is then tubularized around a small-diameter catheter and anastomosed to the proximal end of the ureter in end-to-end fashion. The distal aspect of the reconstructed tube is sutured to the psoas tendon to prevent migration of the bladder and ensure a tension-free reconstruction. The patient will experience a signiﬁcant reduction in bladder capacity following this procedure.
UPPER OR MIDURETERAL DEFECTS
A ureteroureterostomy is typically performed to bridge short defects in the midureter. It consists of anastomosis of the two free ends of a ureter after a short segment (2 to 3 cm) has been excised. The proximal and distal ureteral ends are spatulated and anastomosed over a stent in a water-tight and tension-free fashion.
There are several invasive strategies for the management of high-grade vesicoureteral reﬂux (VUR, see Plate 2-21), and the cross-trigonal ureteral reimplantation is one of the most popular and effective techniques. In this procedure, the reﬂuxing ureter is dissected free of its attachments to the bladder wall, then advanced through a new submucosal tunnel that extends toward the opposite side of the trigone. The signiﬁcantly lengthened intramural segment prevents further reﬂux. The surgery begins with a transverse incision approximately one ﬁngerbreadth above the pubis to the lateral edges of both rectus muscles. The rectus fascia is incised transversely, and fascial ﬂaps are raised. The rectus muscle bellies are longitudinally divided in the midline until the pubis is reached, then a self-retaining ring retractor is inserted to expose the bladder.
The peritoneum is identiﬁed and avoided, and the bladder is opened from the dome to just above the bladder neck. Traction sutures can be used to secure the inferior aspects of the cystotomy to the rectus fascia. The self-retaining ring retractor is repositioned to achieve a clear view of the trigone and ureteric oriﬁces. Rolled moist gauzes are counted and placed into the dome of the bladder.
Ureteroscopy refers to the direct visualization of the ureter and renal pelvis using an endoscope. It is indicated for the treatment of numerous conditions, including renal and ureteral stones, ureteropelvic junction obstructions, ureteral strictures, and upper tract malignancies. It may also be performed to remove foreign bodies, such as a proximally migrated ureteral stent. Finally, it may be performed to evaluate abnormal urine cytology ﬁndings, ﬁlling defects on retrograde pyelography, or hematuria.
Ureteroscopes are small endoscopes that can be either semirigid (minimal bending of the straight metal shaft) or ﬂexible (with an actively or passively deﬂectable distal tip). Both types feature optics consisting of either ﬁberoptic bundles or, more recently, a distal sensor. All ureteroscopes have at least one working channel, which is used for irrigation and through which laser ﬁbers, stone baskets, and other devices may also be deployed. The size (outer diameter) of a ureteroscope is given in the French scale (1 Fr 0.33 mm).
URETEROSCOPY: DEVICE DESIGN AND DEPLOYMENT
Semirigid ureteroscopes are primarily used to diagnose or treat pathology in the mid to distal ureter (i.e., below the iliac vessels). They have a tapered distal tip and typically possess one large working channel or two smaller working channels. The advantages of semirigid ureteroscopes over ﬂexible ureteroscopes include larger working channels, improved stability in the distal ureter, and easier ureteral access. Disadvantages include the potential for urethral trauma during ureteroscope insertion, as well the potential for ureteral trauma during intubation of the ureteric oriﬁce and manipulation of the ureteroscope within the ureter.