Neonatal intervention for severe antenatal pyelocaliectasis
Article Outline
Abstract
The postnatal management of the antenatally detected ureteropelvic junction obstruction relies on several factors, including the degree of hydronephrosis detected postnatally, the renogram washout curve, and the degree of renal function. It is imperative for the urologist to review all renal scans because of the inherent pitfalls in performing and interpreting these studies. A select population demonstrating severe pyelocaliectasis and poor function exists in which an intraoperative renal biopsy may be a better predictor of future renal function when compared with the preoperative renal scan. We present a patient with poor renal function that normalized with early surgical intervention.
We report the normalization of renal function after early surgical intervention for an antenatally detected severe ureteropelvic junction (UPJ) obstruction. We advocate an approach that emphasizes an early complete evaluation and a surgical approach to treat patients with marked diminution of function on renal scan.
Case report
A gravida 2, para 2 woman spontaneously delivered a 32-week-gestation male infant at a peripheral hospital. Although the initial evaluation detected no abnormality, the patient was monitored in the neonatal intensive care unit for prematurity. The pediatric urology service was consulted.
A renal ultrasound was obtained at 3 days revealing right Society for Fetal Urology grade IV and left Society for Fetal Urology grade I pyelocaliectasis; the ureters were not visualized1 (Fig. 1). There was no evidence of vesicoureteral reflux. A circumcision was performed, and prophylactic antibiotics were initiated. At 3 weeks, a diethylenetriaminepentaacetic acid (DTPA) well-tempered diuretic renal scan revealed a profoundly poorly functioning right kidney with poor tracer washout2 (Fig. 2). After evaluation of the renal scan, an overestimation of renal function may have occurred because of the generous region of interest generated for the right kidney.
FIGURE 1.
Renal ultrasound at 3 days of age demonstrating Society for Fetal Urology grade IV pyelocaliectasis.
FIGURE 2.
Preoperative Lasix DTPA renal scan demonstrating split renal function of only 6% for the right kidney.
The patient was taken to the operating room, and a retrograde pyelogram confirmed a right UPJ obstruction. The patient was placed in the dorsal lumbotomy position. On renal exploration, good renal parenchyma was encountered, and a dismembered pyeloplasty was performed. A 6-month postoperative DTPA renal scan revealed almost complete normalization of renal function, as well as substantial improvement in the tracer washout curve (Fig. 3).
FIGURE 3.
(A) Postoperative Lasix DTPA renal scan demonstrating almost complete normalization of function of right kidney with split function of 48%. (B) Postoperative Lasix DTPA washout curves demonstrating a nonobstructive flow pattern for the right and left kidneys.
Comment
Early surgical intervention for antenatal UPJ obstruction with poor renal function offers the pediatric urologist the opportunity to salvage the renal function before irreversible renal damage occurs. Advocates of delayed intervention argue that the populations that benefit from this intervention comprise only 7.5% to 8% of those patients detected after birth. However, the identification of those patients with poor renal function who will benefit from surgical intervention is extremely difficult.
King et al.3 in 1984 were initial advocates of early surgical intervention and postulated that the window for surgical correction was 3 months of age. They theorized that normalization of renal function could only occur if surgical intervention was performed before the development of compensatory hypertrophy. They supported this theory by demonstrating a greater return of renal function in a cohort of patients with poor function that was corrected before 1 year of age compared with a cohort of patients older than 5 years of age. However, none of their patients demonstrated poor renal function measuring less than 5% on the preoperative renal scan. In 1988, Dowling and associates4 demonstrated a more pronounced return of renal function when surgical intervention was performed before 1 year of age by analyzing 41 patients. We favor early surgical intervention for the poorly functioning UPJ obstruction if the renal parenchyma is adequate at renal exploration.
A recent trend toward delayed intervention appears to contradict these findings.5 In 1990, Ransley et al.5 proposed observation as an effective method to limit the number of needless surgical interventions, as well as preserve renal function in a significant number of patients. They evaluated 112 patients with antenatally detected UPJ obstruction. In 9 patients with poor function, defined as less than 20%, they used pigtail catheter drainage; in 3 of these 9 patients, renal function improved and was repaired.5 In 1994 Koff and Campbell6 followed up 104 patients irrespective of the degree of pyelocaliectasis, renal scan washout, or renal function. They identified 16 patients with poor renal function, defined as less than 40%. In 15 (94%) of the 16 patients, renal function normalized with observation.6 However, none of these patients demonstrated a preoperative renal function of less than 5%.
In 1995, Elder et al.7 demonstrated that preoperative renal scans might not be the best predictor of future renal function in cases of a poorly functioning UPJ obstruction. They evaluated 55 patients who all had undergone preoperative renal scans, intraoperative renal biopsies graded by histologic signs of obstruction, and dismembered pyeloplasties. In the population in which the kidneys were functioning suboptimally (less than 40%), 34% of the renal biopsies were normal or nearly normal. In our patient, good renal parenchyma was found at renal exploration, and almost complete normalization of renal function occurred after surgical intervention. If performed, a renal biopsy would probably have revealed normal renal tissue. The outcome of our patient, similar to those in the study by Elder et al., confirms that the preoperative renal scan is not a valid predictor of future renal function. No historical cases have been identified in published reports in which normalization of renal function occurred with observational therapy when the initial renal function was as low as that identified in our patient. Therefore, we conclude that surgical intervention played an important role in the rapid normalization of renal function seen in our patient.
Decisions concerning surgical intervention, in part, are based on the renal scan results. Our patient demonstrated profoundly poor function on renal scan. The quality of the scan was poor but underscores the inherent flaws associated with this type of imaging. First, the urologist should personally review all images and not rely solely on the official report. Next, several pitfalls frequently occur with this type of imaging. The technician, not the physician, frequently dictates when to assess for renal function (2 to 3 minutes), as well to map the region of interest. In our patient, the region of interest was probably generously mapped and overestimated the actual renal function. In contrast, one could argue that with an acute obstruction, renal blood flow would be reduced, and the renal scan might underestimate the actual renal function. Our patient revealed significant pyelocaliectasis antenatally and did not represent a case of acute obstruction, and it is unlikely the scan underestimated the renal function.
In summary, a select population of patients exists who have been identified antenatally but postnatally demonstrate severe pyelocaliectasis and poor function on the renal scan and will benefit from immediate surgical intervention. We use a team approach with antenatally detected UPJ obstruction that includes the urologist, obstetrician, and pediatrician. Postnatally, prophylactic antibiotics are initiated, and circumcision is recommended for all boys. A renal ultrasound and voiding cystourethrogram are performed and, when indicated, a nuclear renogram. All renal scans are performed after 3 weeks, when glomerular filtration is adequate to estimate renal function. In the neonatal period, it is imperative that the urologist review all renal scans and not rely solely on the official written report. In cases of severe pyelocaliectasis and poor renal function, we now perform intraoperative renal biopsy at the time of renal exploration. In the future, prospective controlled clinical trials may confirm that the results of these biopsies may dictate the type of surgical intervention performed.
References
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PII: S0090-4295(99)00359-3
© 1999 Elsevier Science Inc. All rights reserved.
