OVERVIEW

What is an ectopic kidney?

An ectopic kidney refers to a fully developed kidney that fails to reach its normal position, leading to various urinary system abnormalities^[1]. It is generally believed that during embryonic development, abnormalities in renal vascular development prevent the kidney from reaching its normal location, causing it to remain in the pelvis, thorax, or cross to the opposite side.

Asymptomatic patients do not require treatment, while those with significant symptoms may need surgical intervention.

Is an ectopic kidney common?

No, it is rare. Autopsy reports indicate an incidence rate of 1:500 to 1:1200, with an average of 1:900—meaning one ectopic kidney is found in every 500 to 1200 autopsy reports, averaging one in every 900. Ectopic kidneys are slightly more common on the left side than the right, and bilateral ectopic kidneys are extremely rare^[2].

SYMPTOMS

What are the manifestations of ectopic kidney?

Generally, the following manifestations may occur, though some patients may have no symptoms:

• Lower abdominal pain: Presents as persistent dull pain;
• Digestive system symptoms: Due to the ectopic kidney compressing the gastrointestinal tract, patients may experience nausea, vomiting, and other symptoms;
• Urinary system symptoms: Due to compression of the bladder by the ectopic kidney, patients may experience frequent urination, urgency, and other symptoms;
• Abdominal mass: A solid, immobile mass with uniform texture that does not shift with body position;
• Other symptoms: Ectopic kidneys are often associated with kidney stones, infections, hydronephrosis, etc., and may present with distending pain in the kidney area, pyuria, or even hematuria.

CAUSES

What causes ectopic kidney?

During the 4th week of embryogenesis, the ureteric bud forms and combines with the metanephric mesenchyme in the 5th week. It continues to develop, migrates cephalad, and rotates medially along its axis, reaching the renal fossa by the 8th week of gestation. Incomplete or abnormal kidney ascent leading to ectopic kidney may result from underdeveloped ureteric buds, defective metanephric mesenchyme, genetic abnormalities, or maternal kidney diseases during pregnancy^[1].

Who is commonly affected by ectopic kidney?

Ectopic kidney is a congenital condition with no clearly defined high-risk population.

Is ectopic kidney hereditary?

No. Current data does not suggest this condition is hereditary.

DIAGNOSIS

How is ectopic kidney diagnosed?

Ectopic kidney can be diagnosed through physical examination, excretory urography, and imaging tests:

• Physical examination: If a mass is palpated in the abdomen that does not change with body position, ectopic kidney is highly suspected, and further tests are needed for confirmation.
• Excretory urography: This can reveal the kidney's position, size, and shape, aiding in the diagnosis of ectopic kidney.
• Ultrasound (B-scan): No kidney echo is detected in the normal renal area, and the ipsilateral adrenal gland shows a "lying flat" sign^[1].
• CT scan: This clearly displays the morphology of the ectopic kidney and the entire ureter, enabling definitive diagnosis of pelvic ectopic kidney^[3].
• Magnetic resonance imaging (MRI): This is also an important method for diagnosing ectopic kidney^[3], accurately determining its location.

TREATMENT

Which department should be consulted for ectopic kidney?

Nephrology, Urology.

How is ectopic kidney treated?

For asymptomatic patients, no special treatment is usually required. However, if the ectopic kidney is complicated by other conditions, surgical intervention may be necessary.
Surgical treatment: Ectopic kidneys are more prone to urinary tract stones and hydronephrosis, mainly due to abnormal kidney position, malrotation, or vascular malformations compressing the upper ureter or renal pelvis, causing obstruction.

When kidney or ureteral obstruction is severe, nephrectomy may be required. If kidney stones are present but the ureter is intact, endoscopic surgery may be performed to treat the stones. However, endoscopic surgery has higher patient requirements and should be approached with caution^[4].

Can ectopic kidney be cured?

No. If the ectopic kidney is asymptomatic, no treatment is needed. If complications arise, active treatment should be pursued to prevent worsening of the condition, along with regular follow-up examinations.

DIET & LIFESTYLE

What should patients with ectopic kidneys pay attention to in daily life?

• Asymptomatic patients can live normally without worry. If symptoms occur, seek medical attention promptly.
• Avoid strenuous exercise, such as boxing or soccer, to prevent kidney damage. Opt for gentle activities like jogging or yoga.
• Schedule regular check-ups to monitor and prevent worsening of the condition.

What dietary precautions should patients with ectopic kidneys take?

• Post-nephrectomy patients should fast initially, transitioning to liquid foods (e.g., rice porridge, noodle soup) after about three days.
• Avoid spicy, irritating, or raw/cold foods.
• Abstain from alcohol to protect kidney function.
• Consume moderate amounts of high-quality proteins like fish and meat for balanced nutrition.

PREVENTION

Can ectopic kidney be prevented? How to prevent it?

It cannot be prevented. Ectopic kidney is caused by congenital factors, and there are currently no effective preventive measures.