Inflammatory Renal Diseases
Inflammatory renal diseases commonly producing flank pain include
acute pyelonephritis, pyelitis, renal carbuncle, and perinephritic abscess. Spiking
fever is an important associated finding that suggests the presence of infection.
The most prominent sign is tenderness in the flank. Because the kidneys are retroperitoneal
organs, peritoneal signs develop very late. The differential diagnosis must include
pneumonitis, pancreatitis, appendicitis, and cholecystitis. Oral or parenteral narcotics
are very effective for pain control. Systemic antibiotics and fluid resuscitation
are important for the management of renal infections.
Perinephritic fasciitis is an inflammation of the renal capsule
and fascia of Gerota, and it may follow a perinephritic abscess. Depression of the
immune system (as a result of human immunodeficiency virus infection, chemotherapy,
radiotherapy) and sickle cell disease are the major risk factors. Perinephritic
abscesses need to be drained. Nonsteroidal anti-inflammatory drugs (NSAIDs) are
effective in treating the associated reflex skeletal muscle spasm.
Idiopathic nephralgia is a rare condition that mimics renal pain
and other urologic symptoms. The pain is thought to originate from uncoordinated
hyperactivity and spasms of calyces and the renal pelvis. A comprehensive psychological
evaluation may be required to eliminate psychological factors as a source of pain.
Diagnostic and therapeutic paravertebral blocks may help diagnose and treat this
disabling pain condition.
Pseudorenal pain syndromes are caused by genital nerve entrapment
and ilioinguinal neuropathy after inguinal surgery, and they may mimic renal pain.
Referred pain in the dermatomal distribution is very characteristic of these conditions.
Diagnostic and therapeutic ilioinguinal or genitofemoral nerve blocks help establish
the diagnosis and treat this pain. In congenital polycystic kidney disease, renal
pain is caused by distention of the cysts and stretching of Gerota's fascia. Hemorrhage
in the cysts, rupture of the cysts, or infection produce exacerbation of pain. Surgical
intervention, including percutaneous drainage of solitary renal cysts, may relieve
the symptoms. Renal vein thrombosis and renal infarctions cause acute or acute-on-chronic
pain syndromes. Along with treatment of shock and embolectomy, narcotics are used
to control pain.
