A fetal pelvic kidney is a condition that results when the kidneys fail to ascend to their normal position above the waist and remain in the pelvis because they are blocked by blood vessels in the aorta. (See the illustration to the right) Developing kidneys may also fuse together causing what is known as a "horseshoe kidney" because it forms a U-shape structure. (See illustration below.)
In the U.S. it is estimated that one in every 500 births are affected by fetal pelvic kidney.
A fetal pelvic kidney or horseshoe kidney is generally diagnosed by ultrasound (sonogram) examination before birth. Evaluation of the kidneys is part of the routine ultrasound examination done by many obstetricians as part of their prenatal care around the 20th week of pregnancy.
No symptoms are present in the fetus; after birth, one-third of all children diagnosed with this condition do not have any symptoms because the rest of the urinary system has developed normally. However, one-third of all children born with a pelvic kidney have other complications either with their cardiovascular system, the central nervous system or their urinary system. Symptoms directly associated with the horseshoe kidney can include urinary tract infection, kidney stones or hydronephrosis. (Learn about fetal hydronephrosis.)
If there are no symptoms associated with the kidney anomaly, then no treatment is necessary. However, if other problems such as obstruction or reflux are associated with the finding, then the symptoms or other conditions will be addressed through surgery or medication.
The long-term outlook is generally very good for these children if they have no other associated conditions. The overall outlook generally depends on the severity of their other conditions. Additionally, it is recommended that children with this condition should wear a “First Alert” necklace or bracelet that informs other medical professionals of the condition. This will prevent any problems or misdiagnosis if the pelvic kidney is unexpectedly encountered during surgery or on a physical exam by another health care professional.