Pelvic Kidney

Published on 10/03/2015 by admin

Filed under Obstetrics & Gynecology

Last modified 22/04/2025

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Pelvic Kidney

Synonyms/Description

Ectopic location of kidney—normal variant

Etiology

The incidence of pelvic kidney is reported as being between 1 in 2200 and 1 in 3000. The normal human kidney migrates to the renal fossa from a pelvic location early in embryonic development, typically before the 10th week of gestation. The congenital failure of this migration results in a pelvic kidney. Although a pelvic kidney is defined as a normal variant, it is associated with Müllerian duct anomalies such as uterine malformation (see Müllerian Duct Anomalies). Pelvic kidney is the most common type of renal ectopia and is typically clinically asymptomatic. However, ectopically located kidneys are at increased risk of urinary tract infection, stone formation, and trauma.

Ultrasound Findings

Pelvic kidneys that have a normal reniform appearance can easily be recognized as an ectopic kidney. It is important to check the corresponding renal fossa to confirm the absence of the kidney in its normal location before diagnosing a pelvic kidney. If there are cysts or fluid collections associated with the pelvic kidney, the correct diagnosis may be more challenging, and it is crucial to consider the diagnosis of ectopic kidney with hydronephrosis and hydroureter. The patient may also have an associated uterine anomaly, so a transvaginal gynecologic ultrasound should be included as part of the evaluation.

Differential Diagnosis

An abnormal-appearing pelvic kidney may result in misdiagnosis when there is hydronephrosis, large cystic structures, or stones. Ureteropelvic junction (UPJ) obstruction has been reported in 22% to 37% of ectopic kidneys. A cystic or hydronephrotic kidney may be mistaken for an adnexal cystic mass such as an ovarian neoplasm or hydrosalpinx (in the case of a dilated ureter). Ectopic kidneys are associated with Müllerian duct anomalies, which may further confuse the sonographic appearance of the other pelvic organs.

Clinical Aspects and Recommendations

Pelvic kidneys are most often incidental and not clinically significant; however, they are associated with Müllerian duct anomalies, which can cause significant reproductive, mostly obstetric, complications. Therefore when an ectopic kidney is identified in a patient of reproductive age, sonographic evaluation of the reproductive tract, preferably 3-D, must be documented.
Occasionally, ectopic kidneys can be diseased and related to lower abdominal pain if there are renal stones, hydronephrosis, or cysts or pyelonephritis. Rarely, renal masses such as malignancies have been identified in pelvic kidneys.

Figures

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Figure P3-1 Typical right pelvic kidney seen transvaginally, adjacent to the vaginal probe. It is important not to mistake this structure for a solid pelvic mass.

 

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Figure P3-2 Right pelvic kidney (arrows) with a common malrotation, which resulted in mild hydronephrosis.

 

Suggested Reading

Cinman N.M., Okeke Z., Smith A.D. Pelvic kidney: associated diseases and treatment. J Endourol. 2007;21:836–842  Review.

Debenedectis C.M., Levine D. Incidental genitourinary findings on obstetrics/gynecology ultrasound. Ultrasound Q. 2012;28:293–298.

Hall-Craggs M.A., Kirkham A., Creighton S.M. Renal and urological abnormalities occurring with Müllerian anomalies. J Pediatr Urol. 2011;28:27–32.

Meizner I., Yitzhak M., Levi A., Barki Y., Barnhard Y., Glezerman M. Fetal pelvic kidney: a challenge in prenatal diagnosis? Ultrasound Obstet Gynecol. 1995;5:391–393.

Yildirim I., Irkilata H.C., Aydur E., Zor M., Basal S., Goktas S. Different clinical presentations of pelvic ectopic kidneys: report of two cases and review of the literature. Urologia. 2010;77:212–215  Review.

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