Hydronephrosis due to PUJO: Diagnosis and Management
Hydronephrosis refers to the dilation or swelling of the kidney's pelvis and calyces due to the accumulation of urine. One of the most common causes of this condition in infants and children is Pelvi-Ureteric Junction Obstruction (PUJO). This occurs when there is a blockage or significant narrowing at the point where the renal pelvis meets the ureter. Because the urine cannot flow freely out of the kidney and into the bladder, pressure builds up within the kidney. If left untreated, chronic PUJO can lead to irreversible damage to the renal parenchyma, potentially resulting in kidney failure. Fortunately, with modern prenatal screening and advanced surgical techniques like pyeloplasty, the success rate for treating this condition is remarkably high.
1. Understanding the Causes of PUJO
The obstruction at the pelvi-ureteric junction can be caused by several factors. Most cases are intrinsic, meaning the muscular wall of the junction did not develop properly, creating a "kink" or a narrow segment that prevents peristalsis (the wave-like motion that moves urine). Other cases are extrinsic, often caused by a "crossing vessel"—an accessory renal artery that happens to lie across the ureter, compressing it and hindering drainage.
2. Signs and Symptoms Across Different Ages
The presentation of PUJO has changed significantly with the advent of maternal ultrasound.
- Antenatal Diagnosis: Most cases are now detected during routine pregnancy scans, where the fetus is seen to have a dilated kidney.
- Infants: May present with a palpable mass in the abdomen or symptoms of a urinary tract infection (fever, irritability).
- Older Children: Often experience intermittent "Dietl's Crisis"—episodic flank or abdominal pain, especially after drinking large amounts of fluid, often accompanied by nausea and vomiting.
3. Critical Diagnostic Workup
To differentiate between a simple dilated kidney and a true obstruction, doctors use:
- Serial Ultrasounds: To monitor the degree of hydronephrosis using the SFU (Society for Fetal Urology) grading system.
- Diuretic Renogram (DTPA or MAG3 Scan): The gold standard test. A radioactive tracer is injected, and a diuretic (Lasix) is given to see how quickly the kidney clears the fluid. A "flat" or "obstructive" curve indicates the need for surgery.
- Urine Tests: To rule out infection and assess overall renal health.
4. The Decision for Surgery: When is Pyeloplasty Necessary?
Not every child with hydronephrosis needs an operation. Many cases improve spontaneously as the child grows. Surgery is typically indicated if:
- There is a significant decrease in renal function (usually below 40% on a renogram).
- The degree of hydronephrosis is worsening on serial scans.
- The child is experiencing recurrent pain or infections.
- The kidney pelvis is extremely large (massive hydronephrosis).
5. Surgical Technique: Anderson-Hynes Pyeloplasty
The definitive treatment for PUJO is a pyeloplasty. In this procedure, the surgeon cuts out the narrowed or obstructed segment of the junction and reattaches the healthy ureter to the renal pelvis, creating a wide, funnel-shaped opening. This can be performed via a small traditional incision (Open Pyeloplasty) or through minimally invasive methods (Laparoscopic or Robotic-Assisted Pyeloplasty). A temporary plastic tube called a "DJ Stent" is often placed inside the ureter to keep it open while it heals.
6. Post-Operative Care and Recovery
Recovery is usually swift, with most children staying in the hospital for 1–3 days. The stent is typically removed in a minor procedure a few weeks later. Follow-up ultrasounds are performed periodically for several years to ensure the kidney is draining well and the swelling is subsiding. The long-term success rate of pyeloplasty is over 95%, with most children retaining excellent kidney function for the rest of their lives. 250466
