Let us first look at a brief overview of the urinary tract, before discussing the difference between upper and lower urinary tract infection.The urinary tract is the tubular system which transfers urine from the site of its production, kidneys. The urinary tract consists of bilateral ureters opening into the urinary bladder and the urethra which passes urine from the urinary bladder to the exterior. This tubular system makes a continuous passage for the urine flow. This system is lined by a special type of epithelium called urothelium. The renal pelvis which receives urine from the renal tissue and to the ureters is known as the Upper urinary tract. The urethra and the bladder storage is referred to as The Lower urinary tract. Infections of the urethra (urethritis) and the bladder (cystitis) are referred to as lower urinary tract infections. Involvement of the ureters and the kidneys (pyelonephritis) is referred to as upper urinary tract infections. Therefore, the key difference between lower and upper urinary tract infections is determined by the anatomical involvements. However, there could be situations where the whole tract is infected causing pan urinary tract infections. Lower urinary tract infection can easily spread to involve upper tracts causing both upper and lower urinary tract infections together.
What is Upper Urinary Tract Infection?
Upper urinary tract infection or pyelonephritis is a serious infection which can sometimes lead to death. These infections are commonly caused by gram-negative bacilli derived from the gut. Patients with anatomical abnormalities of the urinary system as well as patients with immune suppression are prone to get pyelonephritis. Clinical features are demarcated by high fever and loin tenderness. The patient can become seriously ill due to septicemia or germs in the blood. These patients need to be admitted to the hospital and should be immediately started on intravenous antibiotics covering gram-negative bacilli after taking urine and blood for culture. If the patient has an obstruction in the urinary excretory system, stent insertion may be required. It is very important to continue antibiotics for an adequate duration as an incomplete regimen can lead to re-infection and complications. Once the acute phase is gone, it is very important to investigate the underlying causes and treat them appropriately (e.g. removal of renal stones). Complications of upper urinary tract infections are renal abscesses, acute renal failure, chronic pyelonephritis, etc.
What is Lower Urinary Tract Infection?
Lower urinary tract infections or cycto-urethritis is a very common form of infections especially among sexually active women. Women are more prone to get lower urinary tract infections as they have a short urethra which enables the migration of skin organisms easily compared to the longer urethra in males. Therefore, lower urinary tract infections among male as well as infections among children and elderly are considered as significant. Some sexually transmitted diseases such as syphilis also can lead to urethritis. They usually present with severe lower abdominal pain. Lower urinary tract infections should be treated with short causes of appropriate oral antibiotics and can be treated as an outpatient. Special investigations are not required for a simple lower urinary tract infection. However, patients who are not responding to an adequate cause antibiotics, as well as people who get recurrent infections, need to be further investigated.
What is the difference Between Upper and Lower Urinary Tract Infection?
Anatomy
Upper urinary tract infections: Upper urinary tract infection affects renal pelvises and the ureters.
Lower urinary tract infection: Lower urinary tract infection affects the urinary bladder and the urethra.
Cause
Upper urinary tract infections: Upper urinary tract infections are caused by gram negative organisms most of the times.
Lower urinary tract infection: Lower urinary tract infections can be caused by some sexually transmitted pathogen in additional to gram-negative bacilli and skin commensals.
Severity
Upper urinary tract infections: Upper urinary tract infections are more severe.
Lower urinary tract infection: Lower urinary tract infections are less severe.
Symptoms
Upper urinary tract infections: symptoms include loin pain and marked loin tenderness.
Lower urinary tract infection: Symptoms include lower abdominal pain, burning micturition and lower abdominal tenderness.
Treatment
Upper urinary tract infections: Upper urinary tract infections should always be treated with intravenous antibiotics.
Lower urinary tract infection: Lower urinary tract infections can be treated with a course of oral antibiotics, and no special investigations are required in uncomplicated cases.
Complication
Upper urinary tract infections: Upper urinary tract infections can be ended up with acute renal failure, renal abscesses, septicemia, and death, etc.
Lower urinary tract infection: Lower urinary tract infections usually do not lead to serious complications.