pediagenosis: Urinary
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Showing posts with label Urinary. Show all posts
Showing posts with label Urinary. Show all posts

Tuesday, March 9, 2021

CYSTOSCOPY

CYSTOSCOPY

CYSTOSCOPY

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.

 

CYSTOSCOPE DESIGN
Plate 10-37
CYSTOSCOPE DESIGN

CYSTOSCOPE DESIGN

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.

URETERAL RECONSTRUCTION

URETERAL RECONSTRUCTION

URETERAL RECONSTRUCTION

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.

 

URETERAL RECONSTRUCTION
Plate 10-36

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.

URETERAL REIMPLANTATION

URETERAL REIMPLANTATION

URETERAL REIMPLANTATION

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.

URETERAL REIMPLANTATION
Plate 10-35

URETEROSCOPY

URETEROSCOPY

URETEROSCOPY

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.


URETEROSCOPE DESIGN

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
Plate 10-33
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.

RENAL TRANSPLANTATION

RENAL TRANSPLANTATION

RENAL TRANSPLANTATION

The concept of replacing a diseased human organ with tissue from a living or deceased person has existed since ancient times. The different kinds of transplanted tissue include an autograft (tissue from the recipient), an isograft (tissue from an individual with the same genotype, such as a monozygotic twin), an allograft (tissue from a genetically disparate individual from the same species), and a xenograft (tissue from a different species).

As early as 1916, Little and Tyzzer articulated the important differences between these graft types, stating “isografts succeed; allografts are rejected.” A century later, the clinical practice of transplantation remains subject to these laws. Nonetheless, the introduction of modern immunosuppression drugs has led to dramatic improvements in allograft outcomes. As a result, kidney transplantation has become a common intervention.

RECIPIENT OPERATION IN KIDNEY TRANSPLANTATION
Plate 10-26
RECIPIENT OPERATION IN KIDNEY TRANSPLANTATION


Unfortunately, only a small minority of the patients that would benefit from a kidney transplant ever receive one. There is an ever-growing waiting list 84,355 patients in the United States in 2010 that far exceeds the number of annual procedures. In 2009, 16,830 kidney transplants were performed: 10,442 from a deceased donor, and 6388 from a living donor.

RENAL ABLATION

RENAL ABLATION

RENAL ABLATION

Nephron-sparing surgery has become the standard of care for patients with small (<4.0 cm) renal masses (SRM). For young, healthy patients with a low surgical risk, open or laparoscopic partial nephrectomy (OPN/LPN) is preferred. Renal tumor ablative techniques, however, are relatively new developments with increasing application. Such techniques were initially indicated in patients with multiple renal tumors, a solitary kidney, or significant comorbidities that precluded higher risk surgery. In contemporary practice, however, sufficient evidence indicates that ablation may be a reasonable treatment option for all patients with SRMs. The advantages of renal ablation over LPN include less blood loss, shorter hospitalization time, decreased post-operative pain, and a lower complication rate.


LAPAROSCOPIC CRYOABLATION: RETROPERITONEAL APPROACH
Plate 10-24
LAPAROSCOPIC CRYOABLATION: RETROPERITONEAL APPROACH

ABLATION MODALITIES

At present, the clinically viable ablation technologies include cryoablation and radiofrequency ablation. Either can be performed using laparoscopic or percutaneous technique. Both involve placement of probe needles directly into the renal mass.

Thursday, February 18, 2021

PARTIAL NEPHRECTOMY

PARTIAL NEPHRECTOMY

PARTIAL NEPHRECTOMY

Although radical nephrectomy is the standard surgical treatment for large renal tumors, nephron-sparing surgery has become the new standard of care for small (<4.0 cm) renal masses (SRMs).

SIMPLE AND RADICAL NEPHRECTOMY

SIMPLE AND RADICAL NEPHRECTOMY

SIMPLE AND RADICAL NEPHRECTOMY

Simple nephrectomy refers to the surgical removal of the kidney without the renal fascia or ipsilateral adrenal gland. This technique may be employed to treat non-neoplastic, irreversible  kidney  disease that poses an ongoing threat to the patient’s health. Possible indications include chronic pyelonephritis, chronic renal obstruction, extensive untreated nephrolithiasis, trauma, and ischemic nephropathy secondary to renal artery stenosis.

RENAL REVASCULARIZATION

RENAL REVASCULARIZATION

RENAL REVASCULARIZATION

Renal artery stenosis (RAS) is defined as an anatomic narrowing of the main renal artery or its segmental branches, which can lead to secondary renovascular hypertension (RVH) and renal failure if sufficiently advanced. The pathophysiology and diagnosis of this lesion are demonstrated in Plates 4-36 and 4-37. Briefly, the major causes are atherosclerosis, which accounts for about 90% of cases, and fibromuscular dysplasia (FMD), which accounts for most of the remainder. Atherosclerosis, which tends to occur in older individuals with classic risk factors, involves the intimal layer of the artery and develops circumferentially to occlude a progressive fraction of the vessel lumen. FMD, in contrast, causes collagenous dysplasia of either the intimal or medial arterial layers.

PERCUTANEOUS NEPHROLITHOTOMY

PERCUTANEOUS NEPHROLITHOTOMY

PERCUTANEOUS NEPHROLITHOTOMY

Percutaneous nephrolithotomy (PCNL) is a minimally invasive procedure for the treatment of kidney stones. In this procedure, a surgical access tract is established between the skin and the renal collecting system. The tract is typically created under fluoroscopic guidance, with needle puncture followed by tract dilation.

EXTRACORPOREAL SHOCK WAVE LITHOTRIPSY

EXTRACORPOREAL SHOCK WAVE LITHOTRIPSY

EXTRACORPOREAL SHOCK WAVE LITHOTRIPSY

Extracorporeal shock wave lithotripsy (ESWL) is a noninvasive procedure for the treatment of nephrolithiasis. In this procedure, acoustic shock waves are generated external to the patient and focused on the renal stones, which are fragmented into small pieces that can be spontaneously passed in the urine. The skin and surrounding renal parenchyma receive a much smaller dose of energy and therefore remain largely unharmed.

Saturday, February 6, 2021

HEMODIALYSIS, PERITONEAL DIALYSIS, AND CONTINUOUS THERAPIES

HEMODIALYSIS, PERITONEAL DIALYSIS, AND CONTINUOUS THERAPIES

HEMODIALYSIS, PERITONEAL DIALYSIS, AND CONTINUOUS THERAPIES

When kidney dysfunction is severe enough to cause homeostatic abnormalities that cannot be corrected with diet or medications, dialysis is performed to artificially replace the kidney’s major functions. The major goals of dialysis are to support the elimination of nitrogenous waste products, restore fluid and electrolyte homeostasis, and restore normal plasma pH. The major indications are listed in the plate.

RENAL BIOPSY

RENAL BIOPSY

RENAL BIOPSY

A renal biopsy yields a small piece of renal parenchyma for histopathologic examination. Because many renal diseases have essentially indistinguishable clinical findings, renal biopsy is often crucial for establishing the correct diagnosis and devising an effective treatment plan. The procedure is generally uncomplicated and, in most cases, can safely be performed by a nephrologist at the bedside.

INHIBITORS OF THE RENIN-ANGIOTENSIN SYSTEM

INHIBITORS OF THE RENIN-ANGIOTENSIN SYSTEM

INHIBITORS OF THE RENIN-ANGIOTENSIN SYSTEM

As shown on Plate 3-19, the renin-angiotensin system plays an essential role in the regulation of systemic blood pressure. In brief, renin is released from juxta-glomerular cells in response to decreased renal tubular flow, sympathetic input, or decreased stretch of afferent arterioles. Renin catalyzes the conversion of angiotensinogen to angiotensin I, which is rapidly converted by angiotensin-converting enzyme (ACE) into angiotensin II (AII). AII increases blood pressure through direct vasoconstrictor effects on systemic vessels and through various other mechanisms, including increased sodium reabsorption from the renal tubules, potentiation of sympathetic tone, and stimulation of aldosterone and antidiuretic hormone release.

POTASSIUM-SPARING DIURETICS

POTASSIUM-SPARING DIURETICS

POTASSIUM-SPARING DIURETICS

ACTIONS AND MECHANISM

In the connecting tubule and cortical collecting duct, principal cells are responsible for K+ secretion through two major mechanisms. First, the reabsorption of Na+ through apical ENaC channels leaves a negative charge in the tubular lumen, which promotes the secretion of potassium through apical ROM-K channels. Second, increased flow rates through the distal nephron stimulate K+ secretion through apical maxi-K channels.

THIAZIDE DIURETICS

THIAZIDE DIURETICS

THIAZIDE DIURETICS

ACTIONS AND MECHANISM

In the distal convoluted tubule, Na+ and Cl are reabsorbed across the apical surface of the tubular epithelium on NCC symporters. The thiazide diuretics enter the nephron through the organic anion pathway in the proximal tubule, then they bind to the apical surface of NCC symporters and inhibit them.

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