What is an anterolateral malrotated right kidney with a bifid right renal collecting system?

Anterolateral Malrotated Right Kidney with Bifid Right Renal Collecting System

An anterolateral malrotated right kidney with bifid right renal collecting system is a congenital anomaly involving abnormal kidney rotation and duplication of the collecting system, which typically requires no intervention unless symptomatic with urinary tract infections, obstruction, or renal function impairment.

Understanding Renal Malrotation

Renal malrotation is a congenital anomaly of kidney position where the kidney fails to complete its normal rotation during embryologic development. In normal development, the kidneys ascend from the pelvis and rotate medially, positioning the renal hilum (where vessels and ureter enter/exit) medially. In anterolateral malrotation:

• The kidney is abnormally rotated with the renal pelvis facing anterolaterally instead of medially
• This represents incomplete rotation during fetal development
• The condition itself is often asymptomatic and discovered incidentally

Understanding Bifid Collecting System

A bifid collecting system (also called duplex collecting system) is a common congenital anomaly affecting approximately 1% of the population 1:

• Characterized by duplication of the renal pelvis and usually portions of the ureter
• May be partial (Y-shaped bifid ureter) or complete (two separate ureters)
• Often detected incidentally during imaging studies for unrelated conditions
• More common in females than males 2

Clinical Significance

Most patients with these anomalies remain asymptomatic throughout life. However, potential complications may include:

1. Increased risk of urinary tract infections (UTIs) - The most common symptom, occurring in about 35.6% of patients with duplex systems 2
2. Urinary stasis and stone formation - Abnormal drainage patterns may lead to stagnation
3. Hydronephrosis - Obstruction at the ureteropelvic junction can occur
4. Vesicoureteral reflux - More common with duplicated systems

Diagnosis

These anomalies are typically discovered during imaging studies performed for other reasons:

• Ultrasound - First-line imaging modality that can identify malrotation and duplication 1
• CT urography or MR urography - Provides detailed anatomical information about the collecting system and surrounding structures 3
• Intravenous pyelography - Less commonly used today but can demonstrate the collecting system

Management Approach

Management depends on whether the condition is symptomatic:

1. Asymptomatic patients:

   • No intervention required
   • Periodic monitoring may be considered if there are concerns about potential complications

2. Symptomatic patients:

   • Treatment directed at specific complications:
     • Antibiotics for UTIs
     • Surgical intervention for obstruction or reflux causing recurrent infections or renal damage

Potential Complications to Monitor

• Recurrent UTIs - More common with anatomical abnormalities of the collecting system
• Hydronephrosis - May develop if obstruction occurs
• Renal calculi - Altered urinary drainage may predispose to stone formation
• Renal function impairment - Rare unless significant obstruction is present

Special Considerations

When performing procedures on patients with malrotated kidneys:

• Standard imaging approaches may need modification
• Ultrasound-guided access is preferred for interventional procedures as fluoroscopy alone may lead to inadvertent injury to adjacent organs 4
• Surgical planning requires careful assessment of the abnormal anatomy

These renal anomalies may coexist with other congenital abnormalities, particularly in patients with genetic syndromes like 22q11.2 deletion syndrome, where genitourinary tract abnormalities affect approximately 15% of patients 1.

While most patients with anterolateral malrotated kidneys and bifid collecting systems remain asymptomatic, awareness of these anatomical variants is important for clinicians interpreting imaging studies and planning interventions when necessary.