​Kembara Xtra - Medicine - Hydronephrosis

​Kembara Xtra - Medicine - Hydronephrosis 
Dilatation of the renal calyces and pelvis is referred to as hydronephrosis, and hydroureter (dilatation of the ureter) may also be present.

 Obstructive uropathy, which describes the harm to the renal parenchyma brought on by urinary tract obstruction (UTO), should not be confused with hydronephrosis.

Epidemiology: Congenital abnormalities make hydronephrosis more common in children than in adults; it is more common in women for adults under 60 and in males for adults over 60.

Pathophysiology and Etiology 
Hydronephrosis is characterized by elevated pressure in the urine collecting system, which most frequently results from an obstruction of some kind.
Nonobstructive hydronephrosis may be acute or chronic, partial or total, and unilateral or bilateral, and it may be caused by diabetes insipidus or a physiological shift during pregnancy.
The GU system may be obstructed at one of the following levels:
Congenital occlusion of the ureteropelvic junction (UPJ), nephrolithiasis, transitional cell cancer, sloughed renal papillae, blood clot, and fungal ball Nephrolithiasis, transitional cell carcinomas, strictures, sloughed renal papillae, retroperitoneal fibrosis, and extrinsic compression are all conditions that affect the ureter. - Bladder: posterior urethral valves, extrinsic compression, neurogenic bladder
Prostatic hypertrophy, malignancy, and strictures in the urethra
As a result of ureteral reflux, strictures, ureteral compression (from peritransplant lymphoceles, hematomas), and bladder dysfunction, hydronephrosis in a transplanted kidney is more frequent than in native kidneys.
Child Safety Considerations
Antenatal hydronephrosis is typically detected by the US as early as the 12th or 14th week of pregnancy in 1-5% of pregnancies.
An increased risk of postnatal pathology exists in children with prenatal hydronephrosis.
The US exam is the first step in the postnatal evaluation process; further tests, such the voiding cystourethrogram (VCUG), depend on how severe the postnatal hydronephrosis is. It is the most frequent reason for abdominal mass in newborns.
VUR, congenital UPJ blockage, neurogenic bladder, and posterior urethral valves are common etiologies in children, and pediatric diagnostic algorithms differ from adult ones due to distinct differential diagnoses requiring age-appropriate testing.

pregnant women's issues
80% of pregnant women experience physiologic hydronephrosis, which is more noticeable on the right than the left.
Despite its high incidence, most cases of ureteral dilatation are asymptomatic; if they are, ureteric calculus should be taken into consideration and urinary infection must be ruled out. Dilatation is caused by hormonal effects, external compression from an expanding uterus, and intrinsic changes in the ureteral wall.

Symptoms vary depending on the source, severity, location, and degree of obstruction, as well as the patient's medical history.
Hydronephrosis can be accompanied by pain, ranging from nebulous, sporadic discomfort to severe renal colic, despite the fact that it is frequently asymptomatic.
May be related to hematuria

Vomiting and nausea may be brought on by pain or an infection.
The presence of a urinary infection is suggested by fever and chills.
Anuria denotes total obstruction of both kidneys, or unilateral obstruction of one kidney.

Due to poor urine concentration in partial blockage, polyuria may develop.
Chronic kidney disease (CKD) symptoms include anorexia, fatigue, weight gain, edema, shortness of breath, changes in mental status, and tremors due to a protracted blockage.
Weak pee stream, nocturia, straining to urinate, overflow incontinence, urgency, and frequency are signs of bladder outlet obstruction.
General medical and surgical history includes the following conditions: malignancy (extrinsic compression), radiotherapy (ureteric stricture/fibrosis), surgery (iatrogenic obstruction), trauma hematoma or fibrosis, gynecologic disease (extrinsic compression from endometriosis, ovarian masses, and uterine prolapse), smoking (urothelial cancer), and drugs (methysergide-induced retroperitoneal 

clinical assessment 

General indications of volume overload from renal failure include edema, rales, and hypertension (HTN).
- Tachycardia, tachypnea, and diaphoresis with pain
- High fever, if there is an infection
Pelvic exam: pelvic mass, uterine prolapse, palpable enlarged prostate (cancer or benign), urethral meatal stenosis, and phimosis (may be evident, especially in thin youngsters) Abdominal exam: CVA pain, palpable bladder, rarely palpable abdominal mass 

Laboratory Results 
Urinalysis with microscopy reveals pyuria, proteinuria, crystalluria, and hematuria.
Midstream urine sensitivity and culture: Rule out UTI.
Elevated urea and creatinine may be signs of obstructive uropathy, according to the basic metabolic panel. A type 4 distal RTA due to blockage may be indicated by hyperkalemic nonanion gap metabolic acidosis.
Before considering ureteral instrumentation, evaluate the platelet count if there is an infection. CBC: anemia of CKD, leukocytosis.
Prostate-specific antigen (PSA): adult males over 50, abnormal digital rectal exam, or symptoms of bladder outlet blockage 
For detecting malignant cells in urothelial cancers, urine cytology
The majority of the time, US and noncontrast CT scanning are successful at identifying the existence and origin of obstruction.
US: Sensitivity 90%, specificity 84.5% of preferred screening test for hydronephrosis. does not evaluate function and hardly ever determines the kind and degree of impediment. The severity or duration of the obstruction have no relation to the degree of hydronephrosis.
Benefits include the ability to detect renal parenchymal illness (reduced renal volume, increased cortical echogenicity, cortical thinning, and cysts); lack of radiation or contrast exposure; and safety during pregnancy, contrast allergy, and renal failure. - Erroneous good results False-negative findings in 15.5% of cases include parapelvic cysts, VUR, excessive diuresis, and a normal extrarenal pelvis. 10%: retroperitoneal fibrosis, acute obstruction, and calyceal dilatation mistaken for renal cortical cysts. Noncontrast helical CT (NHCT): test of choice for suspected nephrolithiasis. 94–96% sensitivity and 94–100% specificity were reported. Stone is most frequently discovered at the UPJ, pelvic brim, and vesicoureteric junction, which are levels of ureteric luminal constriction. Perinephric stranding, hydronephrosis with hydroureter close to the degree of obstruction, and renal enlargement are typical features in acute obstruction. Renal atrophy may be observed if persistent.
Benefits include not exposing patients to contrast material, saving time and money, and detecting extraurinary pathology.- Drawbacks: does not evaluate function or degree of obstruction; exposes the user to more radiation, albeit reduced radiation dose procedures have demonstrated equivalent accuracy.
Diuretic renal scintigraphy (DTPA or MAG-3 radionuclide renal scan) is only recommended for assessing hydronephrosis without obvious blockage.
Determines total and divided renal function (right vs. left), as well as the existence of real blockage.
- The T1/2 for the tracer's washout is assessed following the administration of furosemide for 20 minutes. T1/2; >20 minutes is blocked, 10 to 20 minutes is ambiguous, and 15 minutes is considered normal by some specialists.
Advantages: safe in contrast allergy and renal dysfunction; no contrast exposure
False-positive results False-negative findings: dehydration or insufficient diuretic challenge; delayed excretion due to renal failure; large dilatation producing a water-reservoir effect of delayed excretion without obstruction.
Multiphase CT with contrast - Stones and edema are found in the non-enhanced phase.
- The parenchymal phase shows decreased enhancement of the renal parenchyma in the presence of acute obstruction; it can identify extraurinary causes of obstruction and estimate the relative glomerular filtration rate (GFR) of each kidney with accuracy comparable to that of a radioactive renal scan. - The delayed phase makes it possible to see soft tissue filling deficiencies (such urothelial carcinoma) and the collecting system.
When NHCT and US are nondiagnostic, magnetic resonance urography (MRU) is recommended. provide information on anatomical structure, function, and prognosis; sensitivity is comparable to US or NHCT for nephrolithiasis (70%) but superior for soft tissue causes, such as strictures. Advantages: no radiation exposure; safe throughout pregnancy; Drawbacks: more expensive; takes longer (35 minutes as opposed to 5 minutes); it is less accessible than CT. Due to the potential of nephrogenic systemic fibrosis, gadolinium is contraindicated in renal failure, especially when GFR is 30 mL/min.
Tests in the Future & Special Considerations
Due to the possibility of developing bacteremia from a urine infection in an obstructed urinary system, fever should be treated as a medical emergency when it occurs in conjunction with hydronephrosis.

Other/Diagnostic Procedures

It is occasionally necessary to do a biopsy, retrograde pyelogram, or cystoscopy to identify the obstruction (for example, a tiny urothelial carcinoma that was missed on imaging) or to check that the distal ureter is healthy before pyeloplasty. Furthermore, such procedures are frequently required to get a firm pathologic diagnosis for mass lesions.

Treatment Prompt drainage is advised in cases of UTI, impaired renal function, or unbearable/persistent pain. Medical treatment: correction of fluid and electrolyte imbalances, pain management, and antibiotics as an adjuvant to drainage if infection is present. - Urethral or suprapubic catheter for obstruction of the bladder outflow
VUR is frequently treated conservatively with antibiotics; surgical care may be necessary in severe instances in children or women of reproductive age. - Ureteric obstruction: retrograde (cystoscopic) or antegrade (percutaneous) stenting.
Medical expulsive therapy (MET) is recommended for urethral stones smaller than 10 mm in patients with managed discomfort, no symptoms of sepsis, and normal renal function.

Procedures Pyeloplasty (open or laparoscopic) and minimally invasive stricture incision (endopyelotomy) are employed with equivalent results in cases of congenital UPJ obstruction and hydronephrosis caused by obstruction.
- Nephrolithiasis: The first line of treatment for impacted upper urethral stones under 2 cm is extracorporeal shock wave lithotripsy (ESWL).
While ureteral stenting prior to ESWL or postureteroscopy is not related with any additional benefit and is linked with greater discomfort and morbidity, ureteroscopy with or without intracorporeal lithotripsy has lower retreatment rates but higher complication rates and longer hospital stays.
- Nephroureterectomy for transitional cell carcinoma - Ureterolysis for idiopathic retroperitoneal fibrosis (releases ureters from inflammatory mass)
Nonobstructed hydronephrosis - VUR: ureteric reimplantation, endoscopic suburethral injection - Prostate disorders: numerous treatment techniques, including transurethral resection of the prostate (TURP) and radical prostatectomy

Admission

Pyonephrosis, an obstruction and infection coexisting, is a genuine urologic emergency needing prompt drainage.
Retrograde (cystoscopic) stenting is frequently challenging, necessitating implantation of percutaneous nephrostomy tube(s), yet both are equally effective.

Follow-up Until renal function stabilizes, serial monitoring of kidney function (electrolytes, BUN, and creatinine) and blood pressure is required.
The severity of renal impairment determines the frequency of monitoring.
A follow-up US to check on the progress of the hydronephrosis after the renal function has stabilized. Consider diuretic radionuclide testing to rule out ongoing blockage if hydronephrosis persists.

Recovery of renal function relies on the etiology, whether a UTI is present or not, and the severity and length of the blockage.
Even after days of total obstruction, some healing is still possible, however some lasting damage may manifest within the first 24 hours. Diagnostic testing has a low predictive value; delays in therapy can result in irreparable kidney damage. It's quite difficult to foresee how incomplete obstruction will proceed.


Complications 

Urine stasis increases the risk of infection and the production of kidney stones. Obstruction results in gradual renal atrophy and irreversible kidney function loss.
Urine extravasation in the perinephric region may result in the spontaneous rupture of a calyx.
Postobstructive diuresis: pronounced polyuria following blockage alleviation
– primarily brought on by fluid and nutrient excess, but may be made worse by decreased renal tubular concentrating power. Over 500 mL/hr of urine may be produced.
– Only enough hypotonic fluid (about 0.45% NaCl) should be added to replace urine losses in order to prevent volume depletion. The diuresis will continue if urine production is replaced with equal volumes of saline.