Flank pain is a common presentation in renal colic.
This page is about Renal colic. For other types of colic, see Colic
Renal colic is a type of abdominal pain commonly caused by kidney stones.
The pain typically begins in the abdomen and often radiates to the hypochondrium or the groin. The pain is often colicky (comes in waves) due to ureteric peristalsis, but may be constant. It may come in two varieties: dull and acute; the acute variation is particularly unpleasant and is often described as one of the strongest pain sensations felt by humans (being worse than childbirth, broken bones, gunshot wounds, burns, or surgery).
Kidney stones (renal lithiasis) are small, hard deposits that form inside the kidneys. The stones are made of mineral and acid salts. Kidney stones have many causes and can affect any part of the urinary tract — from the kidneys to the bladder. Often, stones form when the urine becomes concentrated, allowing minerals to crystallize and stick together, which is generally caused by mild to severe dehydration concentrating the minerals as well as acids in the urine (calcium being the most common, along with uric acid).
Passing kidney stones can be quite painful, but the stones usually cause no permanent physical damage. Nevertheless, the experience is said to be traumatizing due to pain, and the experience of passing blood, blood clots, and pieces of the stone. Depending on the sufferer's situation, nothing more than imbibing significant amounts of water may be called for; in other instances, surgery may be needed. Preventative treatment can be recommended to prevent recurrence.
Prognosis and treatment 
Most small stones are passed spontaneously and only pain management is required. Diclofenac, as well as many other Non-steroidal anti-inflammatory drugs, and antispasmodics like Hyoscine butyl bromide or Otilonium bromide can be used. Although morphine may be administered to assist with pain management, it is often not recommended as morphine raises ureteral pressure, worsening the condition. There is typically no antalgic position for the patient (lying down on the non-aching side and applying a hot bottle or towel to the area affected may help). If the pain is not too intense, a more speedy release of the stones may be achieved by walking. Larger stones may require surgical intervention for their removal, such as percutaneous nephrolithotomy.