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Flank Pain

By

Geetha Maddukuri

, MD, Saint Louis University

Last full review/revision May 2021| Content last modified May 2021
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Pain caused by kidney disorders usually is felt in the side (flank) or small of the back. Occasionally, the pain extends to the center of the abdomen. Usually pain occurs because the kidney’s outer covering (renal capsule) is stretched by a disorder that causes rapid swelling of the kidney or because a stone has entered one of the ureters (tubes connecting the kidney to the bladder). Severe kidney pain is often accompanied by nausea and vomiting Nausea and Vomiting in Adults Nausea is an unpleasant feeling of needing to vomit. People also may feel dizziness, vague discomfort in the abdomen, and an unwillingness to eat. Vomiting is a forceful contraction of the stomach... read more .

Causes of Flank Pain

A kidney stone Stones in the Urinary Tract Stones (calculi) are hard masses that form in the urinary tract and may cause pain, bleeding, or an infection or block of the flow of urine. Tiny stones may cause no symptoms, but larger stones... read more Stones in the Urinary Tract causes excruciating pain when it enters a ureter. The ureter contracts in response to the stone, causing severe, crampy pain (renal or ureteral colic) in the flank or lower back that often extends to the groin or, in men, to a testis. The pain typically comes in waves. A wave may last 20 to 60 minutes and then stop. The pain stops without resuming again when the ureter relaxes or the stone passes into the bladder.

Other disorders that cause pain in the flank include sudden blockage of blood flow to a kidney or the intestine, ruptured and occasionally unruptured abdominal aortic aneurysms Abdominal Aortic Branch Occlusion Abdominal aortic branch occlusion is blockage or narrowing of one of the large arteries in the abdomen that come off of the aorta. Branches of the aorta can be blocked (occluded) due to atherosclerosis... read more , problems with the spine or spinal nerves, musculoskeletal injuries, and tumors that involve the back of the abdomen (retroperitoneum).

Evaluation and Treatment of Flank Pain

If a kidney stone is suspected, the doctor often does computed tomography Computed tomography There are a variety of tests that can be used in the evaluation of a suspected kidney or urinary tract disorder. (See also Overview of the Urinary Tract.) X-rays are usually not helpful in evaluating... read more (CT) or ultrasonography Ultrasonography There are a variety of tests that can be used in the evaluation of a suspected kidney or urinary tract disorder. (See also Overview of the Urinary Tract.) X-rays are usually not helpful in evaluating... read more to determine whether a stone is the cause, the size and location of the stone, and whether it significantly blocks urine flow. An intravenous contrast agent is not used for the CT scan. If the doctor is not sure of the cause of pain, often CT that uses an intravenous contrast agent or another imaging test is done.

The underlying disorder is treated. Mild pain can be relieved by taking acetaminophen or nonsteroidal anti-inflammatory drugs (NSAIDs). Pain from kidney stones may be severe and may require use of intravenous or oral opioids.

Drugs Mentioned In This Article

Generic Name Select Brand Names
TYLENOL
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