الفهرس 
ANATOMY & PHYSIOLOGY OF THE URETEROnly 14 pages are availabe for public view
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Abstract
A
n understanding of the anatomic relations of the ureters is critical to the practice of urology, as well as to the disciplines of gynecologic, vascular, and general surgery. The ureter serves as a critical landmark and is intimately involved with other vessels and organs, making accidental ureteral injury a dreaded consequence of surgery. Thus it is essential that every surgeon operating in this area must be familiar with the special anatomy of the ureter
Urologists divide the ureter beyond the ureteropelvic junction (PUJ) arbitrarily into the proximal, middle and distal part. According to the international anatomical terminology the ureter consists of the abdominal, the pelvic and the intramural segment.
The ureter has 3 physiologic narrowings: (1) the ureteropelvic junction, (2) the crossing over the iliac vessels, and (3) the ureterovesical junction.Also,it has 5 surgical constrictions: (1) Pelviureteric junction (2) Pelvic brim (Crossing of iliac vessels) (3) Crossing of Vas deferens(♂) / Broad ligament(♀) (4) Ureterovesical junction (5) Ureteric orifice (Intravesical).
The causes of uretric stricture are numerous. The widespread use of upper tract endoscopy has led to an increased frequency of iatrogenic ureteral stricture. Early ureteroscopy studies reported ureteral stricture rates of 3%-11% in patients undergoing ureteroscopy for calculus management. More recent studies using smaller fiberoptic endoscopes; laser lithotripsy; and smaller, less traumatic instruments report a ureteral stricture rate of less than 1%.
Ureteral strictures may be classified as extrinsic or intrinsic, benign or malignant, and iatrogenic or noniatrogenic. Intrinsic benign strictures, may be congenital (eg, congenital mid ureteric stricture), radiational fibrosis,iatrogenic, or noniatrogenic (eg, those that follow passage of calculi or chronic inflammatory ureteral involvement [eg, tuberculosis and schistosomiasis]). Intrensic mlignant stricture could be primary (TCC of the ureter) or secondries e.g from UB TCC.
Ureteral strictures are typically due to ischemia, resulting in fibrosis when it follows open surgery or radiation therapy, whereas the stricture is considered nonischemic if it is caused by spontaneous stone passage or a congenital abnormality
Like other forms of TB, GUTB is also caused by the members of Mycobacterium tuberculosis complex. The development of the disease and its progression depends on the interaction between the pathogen and the immune response of the host. The lower and mid ureter are the most commonly affected sites.
Urothelial tumors of the ureter (upper urinary tract) are relatively rare. Ureteral tumors occur about one half as often as tumors located in the renal pelvis. Transitional cell carcinoma (TCC) accounts for more than 95% of urothelial tumors of the upper urinary tract.
Obtain a detailed patient history of prior general medical and surgical history: Malignancy (extrinsic compression), radiotherapy (ureteric stricture/fibrosis), surgery (iatrogenic obstruction), trauma (hematoma or fibrosis), gynecologic disease (endometriosis, ovarian masses, uterine prolapse), smoking (urothelial cancer), drugs (methysergide-induced retroperitoneal fibrosis).
Diagnostic Tests & Interpretation
Laboratory tests
Midstream urine microscopy, culture, and sensitivity: Exclude infection or hematuria.
Creatinine, urea, and electrolytes: May demonstrate rising creatinine and urea if patient developing obstructive uropathy.
Urine cytology for malignant cells.
Imaging
• Ultrasound (US): Test of choice to rule out hydronephrosis:
Limitations of ultrasonography include:
1- Fairly poor ureteral imaging, especially in patients who are obese.
2- Poor sensitivity for detecting cause and level of obstruction.
• Intravenous pyelography (IVP):
It is useful in both functional and anatomic assessment of site, severity and cause of obstruction
• Non-contrast helical computed tomography (NCCT):
NCCT findings are highly sensitive and specific for helping reliably identify hydroureteronephrosis and the site of dilation. Also, ureteral wall thickness, imbedded or extruded calculi, and urinary extravasation can be appreciated.
• Multiphase contrast-enhanced CT:
Contrast CT scan may be the best test for evaluating extrinsic causes of obstruction and evaluating malignant ureteral obstruction.
• Radionuclide renal scan (diuretic renal scintigraphy):
The diuretic renal scan allows the measurement of clearance of the radiopharmaceutical over time and the calculation of renal blood flow, which correlates to relative renal function.
Magnetic resonance urography (MRU) :
If contrast is contraindicated (creatinine >2 ng/dL), it is superior to non-contrast CT in diagnosing soft-tissue causes including strictures. MRI is used safe in pregnancy .
Diagnostic Procedures
• Intraluminal ultrasound
o Advantages include the ability to assess ureteral submucosal and periureteral abnormalities (eg, fibrosis, vascular structures).
• Retrograde pyelography
o This study very useful because it yields excellent ureteral-mucosal detail in the absence of intravenous contrast and is often used in preparation for endoscopic or open surgery to repair a ureteral stricture.
• Ureteroscopy and biopsy
Histologic findings of benign ureteral strictures are nonspecific. Scar formation with collagen deposition and inflammatory infiltrate may be prominent. Radiation strictures may demonstrate a lack of cellularity and vascular hypertrophy with acellular matrix. Malignant strictures have characteristics of the specific carcinoma pathology, most commonly TCC. (i.e small urothelial cancer missed on imaging).
Management of ureteral strictures varies depending on stricture severity, location, etiology, as well as the patients’ goals and overall health. The least invasive treatments include ureteral stenting, endoscopic dilation and/or ureterotomies, or chronic nephrostomy tubes (tubes that enter the skin and drain the renal pelvis directly). Surgical reconstruction involves open or laparoscopic/robotic repair or excision and tissue replacement of the stricture.
Currently no accepted medical treatment of ureteral strictures that follow spontaneous passage of calculi or chronic inflammatory ureteral involvement, as in tuberculosis and schistosomiasis. Ureteric stricture is a feared manifestation of genitourinary tuberculosis (GUTB) with the commonest site being the lower ureter. Once the diagnosis of GU TB is confirmed on investigations, the patients should be put on multidrug antituberculous drugs (ATT). The treatment of GUTB stricture mostly requires some kind of intervention after a brief period of antituberculous medicines with or without steroids.
The lower and mid ureteric stricture are the most common urological complication of urinary schistosomiasis. In the active or acute phase of the disease, drug treatment ( praziquantel ) is often curative. In the chronic stages, additional Surgical treatment are often necessary for complete treatment.
A- ENDOSCOPIC MANAGEMENT:
1- Endoscopic Balloon Dilatation:
The most common initial management of benign ureteral strictures is balloon dilation, followed by stent placement for 4-6 weeks. Success rates are generally better for non ischemic, single and short (<2cm) ureteral strictures than for ischemic multiple and longer (>2cm) strictures.
2- Endoureterotomy:
Endoureterotomy is commonly performed for benign strictures and boasts a higher success rate than balloon dilation. The most important aspect of this treatment is making a full-thickness incision through the entire ureteral stricture, including 1cm of healthy ureteral tissue proximal and distal to the stricture.
3- Ureteral metal stents:
Metal stents, which have been used to treat end-stage malignant disease, provide proximal decompression, although recurrence of the obstruction is possible. A number of metallic microcoiled stents coated with polymers that retard stone growth are currently on the market.
B- SURGICAL RECONSTRUCTION:
1- Open surgical management:
Open surgical management includes various treatment options such as uretro-ureteral anastomosis, transureteroureter-ostomy (TUU), intestine interposition, buccal mucosal graft and autotransplant.
Mid ureteral strictures, if short, can be treated with ureteroureterostomies the retroperitoneum is exposed, ureter is dissected, diseased segment is excised. The segments are then spatulated and anastomosed end-to-end with absorbable suture.
Mid and distal ureteral strictures can be treated with a Boari flap or psoas hitch. It involves exposing the bladder and identifying healthy ureter. A rectangular flap of bladder tissue is then created anterolaterally and tubularized to replace the diseased ureter. A psoas hitch is performed by making a transverse incision on the anterior bladder. This faciliates fixing the dome and posterior aspect of the bladder to the psoas tendon. The transverse bladder incision is then closed longitudinally.
Long, complex upper tract ureteral strictures have traditionally been managed with ileal interposition, and autotransplantation. Contraindications to ileal ureter substitution include renal insufficiency (serum creatinine level >2 mg/dL), bladder outlet obstruction, inflammatory bowel disease, and radiation enteritis.
2- Laparoscopic and robot-assisted laparoscopic repair:
Laparoscopic and robot-assisted laparoscopic surgery are increasingly used to replicate the results offered by open ureteral stricture surgery. The overall complication rate is higher in the open group (15%) than in the laparoscopic group (8%). With the increasing availability of the da Vinci robot system, this technology has been successfully applied to ureteral stricture disease. It offers the advantage of easier intracorporal suturing and knot tying. Multiple centers have reported small case series documenting successful treatment of mid ureteral stricture with robot-assisted laparoscopic reimplantation.