Excessive urinary tract dilatation and proteinuria in pregnancy: a common and overlooked association?

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.

A best practice position statement on pregnancy in chronic kidney disease: the Italian Study Group on Kidney and Pregnancy

“…Renal colics are more frequent in the second and third trimester; gross hematuria may occur in about one-third of cases [ 325 – 332 ]. Ultrasounds allow limited visualization of ureteral stones; ureteral jet can discriminate between physiological hydroureter and complete obstruction.…”

“…Renal stents have been associated with increase in proteinuria to be considered in the differential diagnosis with PE [ 332 ]. The association with nephrocalcinosis should be kept in mind for allowing diagnosis of underlying metabolic disorders [ 333 ].…”

Preeclampsia from a renal point of view: Insides into disease models, biomarkers and therapy

“…De novo renal disease like lupus nephritis or renal diseases secondary to diabetes or hypertension are other possible causes of increased proteinuria in pregnant women. In addition a symptomatic urinary tract dilatation may also be associated with proteinuria in pregnancy [18] . Thus, the underlying reason for proteinuria in pregnancy is often clinically uncertain.…”

A prospective post-partum evaluation of renal function in preeclampsia

“…Meanwhile, renal failure highly correlates with blood pressure levels and renal function usually assumes the normal range within postpartum. 6 Follow-up of women after delivery has been less-than-optimal in most of the studies. Therefore, knowledge of the long-term outcomes of preeclampsia among Indian women remains limited.…”