Flank is the region that lies between the hip and the last rib, i.e. the side of the body. Flank pain is pain or discomfort occurring in this region or on the side of the body. Flank pain is often caused by a muscle strain, back strain or sprain, problems with the kidneys, ureters, or bladder such as pyelonephritis, kidney stone, and renal abscesses. Other causes of flank pain like gastrointestinal disorders, blood clots, herpes zoster infection, radiculitis, arthritis or infection of the spine, disc disease etc. are also present.
The location and severity of the flank pain generally depends on the underlying cause and varies from moderate to acute and usually worsens with movement, e.g. a right flank pain represents problem in the right kidney whereas a left flank pain indicates a pain in the left kidney. Sometimes a minor condition may give rise to a moderate amount of pain in the flank region that can worsen with increased body movements.
Acute flank pain may be piercing, without any increase or decrease in the pain with movements. The pain in the flank region can spread in a downward direction resulting in testicular pain (in men) and labial pain (in women). Treatment for flank pain depends on underlying cause and may include rest, physical therapy, exercise, drinking lot of fluids, analgesics, anti-inflammatory drugs and antibiotics.
Flank Pain: What Can Cause Pain in the Flank Region
Causes of Right Flank Pain
Right Flank Pain may be caused due to urinary tract infections, bladder infections, kidney problems, and gynecological disorders. Patients suffering from arthritis or diabetes may also suffer from pain on the right side of the flank region. Right flank pain could also be due to muscle pull/strain/spasm or injury in the lower back area. In women, presence of ovarian cyst is one of the major causes of right flank pain.
Causes of Left Flank Pain
Left Flank Pain can be caused due to common problems like muscle pull/strain/spasm or acute infections like Pyelonephritis. Other conditions like gastrointestinal disorders, kidney problems, urinary tract infections and diverticulitis may also cause left-sided flank pain. Kidney stones can also cause pain on the left side of the flank region.
Causes of Lower Left Flank Pain
Lower left flank pain is usually dull and stabbing in nature. Pain in the lower left flank region can occur due to problems in the internal organs or due to problems in the structures external to the abdomen. Lower left flank pain may be harmless or acute. Lower abdominal pain that increases rapidly may be a sign of a serious underlying condition and requires immediate medical attention.
Causes of Flank Pain After Eating
Flank pain after eating occurs on the left side of the abdomen and usually happens just after having food. It is usually stabbing in nature and can be severe or acute enough to make it difficult to perform daily activities, so much so that patients feel an overwhelming urge to stop their work and lie down. Flank pain after eating may arise due to problems in organs like gallbladder, pancreas, appendix and liver. These problems can be diagnosed with the help of endoscopy, CT scan, ultrasound examinations, colonoscopy and blood or urine tests.
Causes of Flank Pain that Comes and Goes or Causes of Intermittent Flank Pain
Intermittent flank pain is a pain in the flank region which comes and goes. The causes of flank pain that comes and goes or intermittent flank pain are Irritable Bowel syndrome (IBS) and patients having Medullary Sponge Kidney (MSK). Flank pain that comes and goes can occur during waking hours or when the patient is asleep. Dull pain may cause mild discomfort, while sharp/intense flank pain may disrupt sleep. Trauma inflicted during sports activities may also cause intermittent flank muscle pain.
Causes of Chronic Flank Pain
Chronic pain in the flank region is a dull, constant pain, which is not severe and may be present for several months. This can be caused due to persisting kidney problems like kidney stones, kidney abscesses, kidney tumors, kidney cysts, kidney infection (acute pyelonephritis) and glomerulonephritis.
Causes of Flank Pain During Pregnancy
Pregnancy related flank pain is caused due to presence of conditions like ureteral obstruction, ovarian tumor, renal stones, ovarian torsion, placental abruption, abdominal muscle strain or rupture.
Medical Conditions That Can Cause Flank Pain
Flank Pain Caused Due To Kidney Problems
Pain in the flanks may arise due to problems affecting the kidneys e.g. kidney stones, renal infection (pyelonephritis), polycystic kidney disorders, abscesses renal infarction, and sometimes kidney cancer. In case of kidney cancer, blood is present in the urine along with flank pain.
Flank Pain Caused Due To Abdominal Aortic Aneurysm (AAA)
Approximately 10% patients having Abdominal Aortic Aneurysms (AAA) have flank pain. If the aneurysm lies immediately beside the ureter, it can give rise to hematuria due to local ureteral trauma or irritation.
Back Ailments That Can Cause Pain in the Flank Region
Back problems like traumatic strain/sprain in the back muscle, back muscle spasm due to intense physical activity, a herniated or slipped disc can result in pain on one side of the body. Patients with acute back conditions, such as spinal arthritis, often experience pain between the back and the abdomen.
Gastrointestinal Disorders Causing Pain In The Flank Region
Flank pain may also arise due to problems in the gastrointestinal system, such as pancreatitis, constipation, splenic flexure syndrome, colon cancer, inflammatory bowel disease, ischemic/microscopic colitis, diverticulosis, appendicitis, infected or enlarged spleen, diverticulitis, stomach ulcers, irritable bowel syndrome, food poisoning etc. Digestive problems may also lead to flank pain and is usually accompanied by other symptoms like abdominal discomfort, nausea and vomiting.
Flank Pain Due To Gynecological Problems
In women, presence of an ovarian cyst, mid-cycle pain (mittleschmerz), polycystic ovarian syndrome, miscarriages, pelvic inflammatory disease, endometritis and ectopic pregnancy may cause flank pain.
Flank Pain Due To Blood Clots
Sometimes, blood clots can obstruct the uterus and cause an acute renal colic attack. These blood clots may arise due to underlying conditions like renal pelvis tumors, parenchymal tumors, hemophilia, glomerulonephritis, sickle cell disease, and angiomyolipoma. Clots can also form as a result of percutaneous renal biopsies.
Pain in the Flank Region Caused Due To Herpes Zoster Infection
Herpes Zoster is a viral infection which gives rise to mild burning pain, generally in the area surrounding the flank. The pain usually arises prior to the appearance of skin lesions characteristic of this infection. Treatment depends on the symptoms, with antiviral agents and analgesics being the medications of choice.
Flank Pain Caused Due To Radiculitis
Radiculitis arises due to trauma or injury to the roots of the lumbar thoracic nerve resulting in pain in the flanks. Pain may also develop due to trauma to the costovertebral junctions. This pain is similar to renal colic if the pain is in the 10th, 11th or 12th ribs. This type of flank pain is usually acute. An injury or scarring of the intercostal nerve can also cause this pain.
Pathophysiology of Flank Pain
Flank pain is actually a symptom of many significant diseases of the urinary system. It can arise from ureteral obstruction along with infection and should be treated promptly; otherwise it could lead to renal damage. The character of flank pain is highly indicative of the cause. Important characteristics of Flank Pain are local or referred pain, acute or chronic or recurrent pain, degree of severity, and duration. There may also be other associated symptoms such as fever, nausea and vomiting, and atrial fibrillation which often help in making an accurate diagnosis. Proximal ureteral or renal pelvic obstruction leads to flank pain that radiates to the ipsilateral testicle. The degree of severity of flank pain is directly related to the severity of the obstruction. When a stone passes into the ureter and becomes lodged in one position, it usually causes severe pain. Flank pain can be very mild or absent in severe but chronic obstruction. Severe ureteral obstruction can lead to irreversible renal damage.
Flank pain is often associated with other less specific symptoms like fever, nausea and vomiting, and tachycardia. Fever indicates that the infection is proximal to the ureteral obstruction and the patient is highly susceptible to septicemia in such a case. Hematuria helps to confirm a urinary cause of the pain though in some cases hematuria may be absent. Ureteral stone is the most common cause of flank pain. Blood clots or sloughed renal papillae passing through the ureter can also cause ureteral obstruction. Blood clots can be the result of many pathologic lesions of the kidney, of which tumors is the most common cause. Patients having a history of analgesic abuse or diabetes mellitus often have renal papillary necrosis. Chronic ureteral obstruction generally causes less severe pain. Sometimes flank pain is also associated with congenital anomalies like ureteropelvic junction obstruction. Renal failure can result from bilateral chronic ureteral obstruction or ureteral obstruction of a solitary kidney and is associated with symptoms such as headache, apathy, lethargy, anorexia, muscle twitching, hypertension, and poor growth of a child. Renal inflammation usually produces localized pain which is not acute or sharp and is associated with other symptoms like fever, leukocytosis, and bacteriuria.
Diseases of the abdomen and chest can also cause flank pain and this pain is less characteristic of the typical “renal colic” seen with acute ureteral obstruction. It is vague, dull, and mild similar to the pain seen with chronic ureteral obstruction, making the differential diagnosis difficult. Correct diagnosis can be arrived at by considering all the diseases that have been discussed, along with associated symptoms, physical examination, urinalysis, and performing specific laboratory tests and radiographic studies.
Signs and Symptoms of Flank Pain
Symptoms depend on the underlying causative condition. The side where the pain is felt indicates the kidney that has been affected. A right flank pain is caused by a problem in the right kidney and a left flank pain suggests a problem in the left kidney. The pain may increase with movements. In severe cases, the pain may be intense and piercing without any change with movements. The pain may spread in a downward direction and result in testicular pain (in men) and labial pain (in women).
Other Associated Symptoms of Flank Pain Are :
- Abdominal pain.
- Frequent urination.
- Muscular tenderness.
- Pain and discomfort while passing urine.
Treatment for Flank Pain
Treatment also depends on the underlying cause. Following treatment is usually recommended for Flank Pain:
- Physical therapy
- Anti-inflammatory drugs
- Antibiotics for kidney infections
- Plenty of fluids
- Hospitalization may be required for kidney stones or infections.
Investigations for Flank Pain
- Abdominal CT scan.
- Retrograde ureteropyelography.
- Urine culture.
- Voiding cystourethrography.
- Ultrasound examination of the abdomen or the kidney.
- Intravenous pyelography (IVP).
- Lumbosacral spine x-ray.
- Blood tests.