From the Guidelines
Ureteropelvic junction obstruction (UPJO) resolves spontaneously in the majority of cases, with most antenatal hydronephrosis being transient with little long-term significance. The likelihood of spontaneous resolution is influenced by several factors, including the severity of the obstruction and the patient's age at diagnosis. According to the study by 1, most antenatal hydronephrosis is mild, and the cause cannot always be determined with certainty, suggesting that many cases may resolve on their own.
Some key points to consider when evaluating the likelihood of spontaneous resolution include:
- The severity of the obstruction, with mild to moderate cases having a better chance of resolving without intervention compared to severe cases
- The degree of hydronephrosis, with less severe cases more likely to resolve spontaneously
- Kidney function, with patients having good kidney function more likely to experience spontaneous resolution
- The patient's age at diagnosis, with infants and young children more likely to experience spontaneous resolution as they grow and develop
The study by 1 highlights the importance of early detection and treatment of obstructive uropathy to mitigate potential morbidity from loss of renal function. However, it also suggests that many cases of UPJO may resolve spontaneously, particularly in infants and young children. A conservative "watchful waiting" approach with regular ultrasound monitoring may be appropriate for mild to moderate cases in infants and young children with good kidney function, as spontaneous resolution is likely to occur in these cases.
From the Research
Spontaneous Resolution of Ureteropelvic Junction Obstruction (UPJO)
- The frequency of spontaneous resolution of UPJO is not well-defined, but some studies provide insight into the natural history of the condition.
- A study published in 2010 2 found that in children with severe bilateral UPJO, the non-operated renal units with grade 3 and some with grade 4 hydronephrosis improved spontaneously after unilateral pyeloplasty.
- In this study, 5 out of 13 patients showed spontaneous improvement of contralateral hydronephrosis at 1 month postoperatively.
- Another study published in 2021 3 mentions that the natural history of UPJO is variable, ranging from spontaneous resolution to progressive loss of function over the first few years of life.
- However, the exact frequency of spontaneous resolution is not specified in this study.
Factors Influencing Spontaneous Resolution
- The studies do not provide clear information on the factors that influence spontaneous resolution of UPJO.
- However, a study published in 2021 4 found that neither patient's age, baseline differential renal function, comorbidities, degree of hydronephrosis, kidney parenchymal thickness, nor kidney biopsy findings consistently predicted a significant increase in differential renal function after pyeloplasty.
- This suggests that the factors influencing spontaneous resolution may be complex and multifaceted.
Clinical Implications
- The possibility of spontaneous resolution should be considered when evaluating and managing patients with UPJO.
- A study published in 2010 2 suggests that delayed pyeloplasty of the opposite side should be considered at 1 month following initial pyeloplasty in children with severe bilateral UPJO.
- Further research is needed to better understand the natural history of UPJO and to develop clear guidelines for evaluation and treatment.