Hematuria

Postrenal hematuria - the presence of blood in urine (because of damage to the urethra and prostate).

A glomerular etiology is suggested by dysmorphic red blood cells, protein, and cellular casts in the urine.[3] This requires the consultation of a nephrologist.[3] Common causes include:

• IgA nephropathy
• Thin glomerular basement membrane disease
• Hereditary nephritis (Alport's disease)
• Benign familial hematuria
• Glomerulonephritis

Idiopathic hematuria is hematuria with an unknown cause. It is considered a glomerular syndrome.[5]

• Urinary stones (i.e. kidney stone)
• Pyelonephritis
• Kidney cancer
• Ureteral cancer

• Urinary tract infection (UTI)
• Benign prostatic hyperplasia (BPH)
• Strenuous exercise
• Bladder cancer
• Urethral cancer

Microscopic hematuria requires medical testing for detection. It is not visible to the naked eye. Rather it requires microscopic examination for detection.[4] It is defined as three or more red blood cells per high-powered field.[3] Another method for detection of microscopic hematuria is the dipstick method. This test works by detecting hemoglobin in a urine sample.[3] False positives can occur with dipstick testing if free hemoglobin or myoglobin are present.[3] "Red urine" can result from the drug phenazopyridine[4].

Hemoglobin in the absence of red blood cells can also turn urine red. The inciting event for hemoglobin in the urine is hemolysis in the bloodstream. Hemolysis is a process where red blood cells lyse or burst. This releases hemoglobin into the bloodstream.[6] Hemoglobin then leaves the bloodstream and enters urinary tract at Bowman's capsule.

• Trauma, especially at the genitourinary area
• Vaginal bleeding

Common causes of hematuria in children are:[7]

• congenital abnormalities –
  • Non-vascular – ureteropelvic junction obstruction, posterior urethral valves, urethral prolapse, urethral diverticula, multicystic dysplastic kidney
  • Vascular – arteriovenous malformations, hereditary hemorrhagic telangiectasias, renal vascular thromboses
• Acute nephritis
• Coagulopathy
• Urinary stones
• IgA nephropathy
• Post-streptococcal glomerulonephritis
• benign familial hematuria
• sickle cell trait or disease
• Alport syndrome

The differential diagnosis can be furthered refined by the temporality of hematuria and associated symptoms. During urination, blood can appear in the urine at the onset, midstream, or later.[6] It can also have associated symptoms. These include nausea, fever, chills, abdominal pain, flank pain, groin pain, urinary frequency, urinary urgency, and pain or discomfort with urination.[3][6]

When hematuria becomes visible during urination can suggest where in the urinary tract the bleeding originates.[6] If it appears soon after the onset of urination, a distal site is suggested.[6] A longer delay suggests a more proximal lesion.[6] In other words, shorter times suggest distal sites while longer times suggest proximal sites. Hematuria that occurs throughout urination suggests that bleeding is occurring above the level of the bladder.[6]

The presence of hematuria without accompanying symptoms should be considered a tumor of the urinary tract until proven otherwise.[6] Other possible causes include acute glomerulonephritis, staghorn calculus, polycystic kidneys, benign prostatic hyperplasia, solitary renal cyst, sickle cell disease, and hydronephrosis.[6] It can also develop after vigorous exercise.[6][3]

Costovertebral angle tenderness suggests upper urinary tract obstruction.[4] A urinary stone is suggested by the presence of renal colic[6]. The presence of a fever suggests pyelonephritis.[4]

The preferred modality is a multi-phasic computed topography (CT) urography.[4] This is a three-phase study that includes a non-contrast phase, an arterial phase, and an excretory phase.[3] The study should sufficiently evaluate the kidney and the urothelium lining the upper urinary tracts.[3] If there are contraindications to this study then alternative studies can be used.[4] One alternative is a magnetic resonance (MR) urography with and without intravenous contrast.[3] Another alternative is a retrograde pyelogram paired with either magnetic resonance imaging of the upper urinary tracts (MRI) or a renal ultrasound (US).[4][3] This imaging assessment is capable of excluding upper tract malignancies.[4]

For patients younger than 35 years old presenting with asymptomatic microscopic hematuria, a cystoscopy may be warranted if risk factors are present.[4]

Evaluations of hematuria that do not reveal pathology require follow up. A urinary cytology may be helpful.[3] A urinalysis should be repeated once a year. Follow up can be discontinued after two consecutive negative urinalyses.[3] Repeat hematuria on follow-up studies warrants repeat upper urinary tract imaging and a cystoscopy.[3] This should be performed within three to five years of the first evaluation.[3]

A 60cc/mL Toomey syringe. 1) Fill syringe with saline. 2) Connect syringe to a catheter port 3) Instill 180cc of saline 4) Draw back 180cc of bladder urine 5) Dispose of medical waste 6) Repeat until all clots are removed

Acute clot retention is one of three emergencies that can occur with hematuria.[8] The other two are anemia and shock.[8] Blood clots can prevent urine outflow through either ureter or the bladder.[8] This is known as acute urinary retention.

Blood clots that remain in the bladder are digested by urinary urokinase producing fibrin fragments.[8] These fibrin fragments are natural anticoagulants and promote ongoing bleeding from the urinary tract.[8] Removing all blood clots prevents the formation of this natural anticoagulant.[8] This in turns facilitates the cessation of bleeding from the urinary tract.[8]

The acute management of obstructing clots is the placement of a large (22-24 French) urethral Foley catheter.[8] Clots are evacuated with a Toomey syringe and saline irrigation.[8] If this does not control the bleeding, management should escalate to continuous bladder irrigation (CBI) via a three-port urethral catheter.[8] If both a large urethral Foley catheter and CBI fail, an urgent cystoscopy in the operating room will be necessary.[8] Lastly, a transfusion and/or a correction of a coexisting coagulopathy may be necessary.[8]

In pediatric populations, the prevalence is 0.5–2%.[9] Risks factor include older age and female gender.[10] About 5% of individuals with microscopic hematuria receive a cancer diagnosis. 40% of individuals with macroscopic hematuria (blood easily visible in the urine) receive a cancer diagnosis.[11]

For more information, please see the section on genitourinary tract injury.