Abstract
BackgroundProteinuria and dilatation of the urinary tract are both relatively common in pregnancy, the latter with a spectrum of symptoms, from none to severe pain and infection. Proteinuria is a rare occurrence in acute obstructive nephropathy; it has been reported in pregnancy, where it may pose a challenging differential diagnosis with pre-eclampsia.The aim of the present study is to report on the incidence of proteinuria (≥0.3; ≥0.5 g/day) in association with symptomatic-severe urinary tract dilatation in pregnancy.MethodsCase series. Setting: Nephrological-Obstetric Unit dedicated to pregnancy and kidney diseases (January 2000-April 2011). Source: database prospectively updated since the start of the Unit. Retrospective review of clinical charts identified as relevant on the database, by a nephrologist and an obstetrician.ResultsFrom January 2000 to April 2011, 262 pregnancies were referred. Urinary tract dilatation with or without infection was the main cause of referral in 26 cases (predominantly monolateral in 19 cases): 23 singletons, 1 lost to follow-up, 1 twin and 1 triplet. Patients were referred for urinary tract infection (15 cases) and/or renal pain (10 cases); 6 patients were treated by urologic interventions (“JJ” stenting). Among them, 11 singletons and 1 triple pregnancy developed proteinuria ≥0.3 g/day (46.1%). Proteinuria was ≥0.5 g/day in 6 singletons (23.1%). Proteinuria resolved after delivery in all cases. No patient developed hypertension; in none was an alternative cause of proteinuria evident. No significant demographic difference was observed in patients with renal dilatation who developed proteinuria versus those who did not. An association with the presence of “JJ” stenting was present (5/6 cases with proteinuria ≥0.5 g/day), which may reflect both severer obstruction and a role for vescico-ureteral reflux, induced by the stent.ConclusionsSymptomatic urinary tract dilatation may be associated with proteinuria in pregnancy. This association should be kept in mind in the differential diagnosis with other causes of proteinuria in pregnancy, including pre-eclampsia.
Highlights
Proteinuria and dilatation of the urinary tract are both relatively common in pregnancy, the latter with a spectrum of symptoms, from none to severe pain and infection
Prevalence of proteinuria in pregnant patients with urinary tract dilatation In the study period (January 2000 - April 2011), 262 pregnancies in 235 women were referred to the Outpatient Unit for Kidney Diseases in Pregnancy
The overall prevalence of proteinuria ≥0.3 g/day associated with urinary tract dilatation was high: 11 singletons and 1 triple pregnancy developed proteinuria before term (46.1% of the overall population; 48% of the singletons, not considering the patient lost to follow-up)
Summary
Proteinuria and dilatation of the urinary tract are both relatively common in pregnancy, the latter with a spectrum of symptoms, from none to severe pain and infection. The possibility that urinary tract obstruction may occasionally cause proteinuria outside of pregnancy is well known, even if not frequently reported [9,10,11]; its degree is usually sub-nephrotic and its pathogenesis is usually related to increased pressure in the renal pelvis, leading to a diuretic response from the contralateral kidney. A relatively recent report dealt with a pregnant patient who developed nephrotic proteinuria In this very well documented case, proteinuria was found to stem from both kidneys at the time of laparoscopic intervention and resolved after pyeloplasty performed a few months after delivery [14]. A few interesting cases had been reported, in which urinary tract dilatation was presumably the cause of severe pre-eclampsia or of kidney function impairment [15,16]. According to a Medline search at June 2011 (combining the terms proteinuria, hydronephrosis, kidney and dilatation with pregnancy), we could locate no surveys of the of the prevalence of proteinuria associated with urinary tract dilatation in pregnancy in the last decade, with the exception of the case mentioned above
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