Aetiological factors in the genesis of pregnancy hydronephrosis

Placental and Renal Pathways Underlying Pre-Eclampsia

Pre-eclampsia is a serious complication of pregnancy characterized by a state of multiorgan hypertensive disorders, with or without proteinuria and possible multiorgan dysfunction. Chronic kidney disease is an established risk factor for the development of pre-eclampsia, as angiogenic homeostasis is altered and the maternal circulation is already hypertensive. Facing pre-eclampsia in the context of chronic kidney disease is a challenging emergency for both the mother and the fetus. The clinical features and the management of this multi-organ disorder are clearly defined in the modern literature but the underlying pathophysiologic mechanisms remain not fully elucidated. Understanding the pathophysiology that mediates the onset of pre-eclampsia itself and in synergy with chronic kidney disease is fundamental for developing prompt prevention strategies, treatment planning, and patient counseling. This review aims to summarize the main molecular mechanisms involved in the process of pre-eclampsia, with a particular focus on the role of the kidneys and hormonal pathways related to renal function in normal pregnancy and pre-eclamptic syndromes.

"Urinary tract dilatation and vesicoureteral reflux - Adult outcomes, who should be followed, and how to follow them"

Long-term adult outcomes of children diagnosed with urinary tract dilatation (UTD) and vesicoureteral reflux (VUR) are not clearly documented in the literature. Likewise, follow-up protocols for these patients as they transition through adolescence and into adulthood vary with institution and cultures. Several studies have shown that individuals diagnosed with VUR in childhood are at higher risk of urinary tract infection (UTI) throughout their lives, even in the setting of prior VUR resolution or surgical correction. This is particularly relevant in patients with renal scarring, who are at higher risk of UTIs, hypertension and renal function deterioration in pregnancy. The risk of adverse maternal and fetal outcomes in pregnancy are higher for women with significant chronic kidney disease (CKD). Patients who underwent endoscopic injection or reimplantation should be counselled on the long-term particular risks associated with each intervention, including calcification of ureteric injection mounds, and the potential challenges of future endoscopic procedures following reimplantation. Although there is no evidence for the direct correlation between conservatively managed UTD in childhood, and symptomatic UTD diagnosed in adulthood, all patients should be aware of the long-term risks of persistent upper tract dilatation. Lastly, bladder-bowel dysfunction (BBD) management in adolescence can be more challenging and may contribute to symptomatic recurrence in this age group.

Kidney Physiology in Pregnancy

A woman's body undergoes a myriad of changes throughout the course of a normal gestation. The kidneys play a central role in driving adjustments that guarantee maternal and fetal well-being, including a dramatic increase in glomerular filtration rate, alterations in tubular function, and changes in electrolyte and acid/base handling. Early in gestation, systemic vasodilation, driven by both a change in quantity of and response to various hormones, leads to increased renal blood flow and glomerular filtration rate. Vasodilation also results in activation of the renin-angiotensin-aldosterone axis, which combined with changing tubular handling causes alterations in total body stores of electrolytes and total body water, resulting in a lower serum sodium concentration. In addition, mild proteinuria, glucosuria, and a decrease in serum calcium and magnesium are common. The primary acid/base change seen in pregnancy is a mild respiratory alkalosis due to progesterone effects. This article provides an overview of the current understanding of the healthy response of the kidneys to pregnancy, an understanding of which is key to caring for the pregnant patient, and early identification of alterations that may indicate underlying kidney pathology in pregnancy.

Kidney Imaging and Biopsy in Pregnancy

Physiologic glomerular, tubular, and structural changes related to pregnancy may complicate the detection of underlying kidney disease in pregnant patients. Imaging studies may provide important clinical information to assist in the diagnosis and treatment of kidney disease during pregnancy. Furthermore, in select patients who develop new or worsening kidney disease in pregnancy, kidney biopsy may be essential to ensure the accuracy of diagnosis and guide treatment choices. This review article will discuss the risks and benefits of various modalities used to image the kidneys and urinary tract during pregnancy to aid in the judicious selection of appropriate imaging studies that are likely to maximize clinical benefit while minimizing fetal risk. It will also highlight the potential benefits and harms associated with antepartum kidney biopsy and will offer strategies for identifying patients who are most likely to benefit from kidney biopsy during pregnancy.

The Changing Landscape of Acute Kidney Injury in Pregnancy from an Obstetrics Perspective

Pregnancy-related acute kidney injury (PR-AKI) is a heterogeneous disorder with multiple aetiologies that can occur at any time throughout pregnancy and the post-partum period. PR-AKI is an important obstetric complication that is associated with significant maternal and foetal morbidity and mortality. Although there has been an overall decline in the incidence of PR-AKI worldwide, a recent shift in the occurrence of this disease has been reported. Following improvements in obstetric care, PR-AKI incidence has been reduced in developing countries, whereas an increase in PR-AKI incidence has been reported in developed countries. Awareness of the physiological adaptations of the renal system is essential for the diagnosis and management of kidney impairment in pregnancy. In this review we scrutinize the factors that have contributed to the changing epidemiology of PR-AKI and discuss challenges in the diagnosis and management of acute kidney injury (AKI) in pregnancy from an obstetrics perspective. Thereafter we provide brief discussions on the diagnostic approach of certain PR-AKI aetiologies and summarize key therapeutic measures.

Vhl deletion in renal epithelia causes HIF-1α-dependent, HIF-2α-independent angiogenesis and constitutive diuresis

One of the earliest requirements for the formation of a solid tumor is the establishment of an adequate blood supply. Clear cell renal cell carcinomas (ccRCC) are highly vascularized tumors in which the earliest genetic event is most commonly the biallelic inactivation of the VHL tumor suppressor gene, leading to constitutive activation of the HIF-1α and HIF-2α transcription factors, which are known angiogenic factors. However it remains unclear whether either or both HIF-1α or HIF-2α stabilization in normal renal epithelial cells are necessary or sufficient for alterations in blood vessel formation. We show that renal epithelium-specific deletion of Vhl in mice causes increased medullary vascularization and that this phenotype is completely rescued by Hif1a co-deletion, but not by co-deletion of Hif2a. A physiological consequence of changes in the blood vessels of the vasa recta in Vhl-deficient mice is a diabetes insipidus phenotype of excretion of large amounts of highly diluted urine. This constitutive diuresis is fully compensated by increased water consumption and mice do not show any signs of dehydration, renal failure or salt wasting and blood electrolyte levels remain unchanged. Co-deletion of Hif1a, but not Hif2a, with Vhl, fully restored kidney morphology and function, correlating with the rescue of the vasculature. We hypothesize that the increased medullary vasculature alters salt uptake from the renal interstitium, resulting in a disruption of the osmotic gradient and impaired urinary concentration. Taken together, our study characterizes a new mouse model for a form of diabetes insipidus and non-obstructive hydronephrosis and provides new insights into the physiological and pathophysiological effects of HIF-1α stabilization on the vasculature in the kidney.

[Physiological hydronephrosis in pregnancy: Occurrence and possible causes. An MRI study]

INTRODUCTION

The etiology of the uretero-hydronephrosis in pregnancy is just hypothesis: hormonal or mechanical hypothesis, only investigated by echographic studies. MRI permits to visualize the entirety of the urinary tract, which can be helpful to find out a mechanical cause.

METHODOLOGY

We have analysed the MRI of 100 asymptomatic pregnant women. We have determined the number and locations of the uretero-hydronephroses and researched whether there is any relationship between the uretero-hydronephrosis and certain abdominal structures. We focused on the psoas muscle and measured its depth, width and calculated its surface by a reproducible method.

RESULTS

The analysis revealed that the uretero-hydronephrosis was predominantly at the right side (63%) and in the majority of the cases limited to the kidney (42%) and/or the proximal third of the ureter (42%). We were able to rule out some proposed etiologies: a compression of the ureter between the uterus and the iliac or ovarian vessels; a protective effect of the left intestinal structures. A link was observed between the psoas muscle and the physiological uretero-hydronephrosis: the ipsilateral psoas muscle seemed smaller in pregnant women presenting a uretero-hydronephrosis.

CONCLUSION

We have highlighted a link between a physiological uretero-hydronephrosis during pregnancy and a lesser developped psoas muscle. The hypothesis proposed is that a smaller psoas muscle would have a less protective effect of the ureter due to a lesser development. This study offers a practical conclusion: a left sided uretero-hydronephrosis during pregnancy and/or including the entirety of the ureter is more probably a pathological hydronephrosis.

LEVEL OF EVIDENCE

4.

Urological disorders and pregnancy: An overall experience

AIM

Pregnancy is an anatomical and physiological altered state and the presence of various urological problems not only aggravates the disease itself, but also results in unfavourable pregnancy outcome. Aim is to highlight obstetric outcome in pregnant women with urological problems.

MATERIALS AND METHODS

Longitudinal prospective cohort study conducted in tertiary care hospital, IPGME and R, Kolkata from Jan 2011 to Dec 2012. All pregnant women with urological problems were included as subjects.

RESULTS

A total of 33 subjects were followed up throughout their antenatal period. Among them majority (72.72%) presented with hydro nephrosis followed by hydroureter (60.6%), PUJ obstruction and pyelonephritis each with incidence of 15.15%, then urolithiasis (12.12%), nephrolithiasis (6.06%) and renal abscess (12.12%). Interventions required were DJ stenting (72.72%), pyeloplasty (15.15%) and others were RURSL, abscess drainage and ATT. The pregnancy outcome was complicated with preterm labor in majority of patients (45.45%), oligohydramnious (18.18%), PIH (9.09%) and still birth (6.06%). Twenty four live birth were there. Majority required NICU admissions as predominantly prematurity was an important concern. Majority women with hydronephrosis underwent DJ stenting.

CONCLUSION

Preterm labor is an important obstetric concern. Vaginal delivery is the choicest mode of termination and LSCS can be reserved for obstetric reason. DJ stenting is safe and practical approach for continuation of pregnancy with hydronephrosis. Regular follow up, vigilant antenatal care and multidisciplinary approach from urologist, obstetrician and neonatologist will bring out successful pregnancy outcome.

Hydronephrosis: an unusual complication of neurogenic bowel in a patient with spinal cord injury: a case report

STUDY DESIGN/METHODS

Case report.

OBJECTIVES

In this case report, a consequence of not following proper care of the bowel affecting the genitourinary system is reported and discussed.

SETTING

United States.

RESULTS/CONCLUSION

Neurogenic bowel and bladder can result from a spinal cord injury. It is necessary for spinal cord injury patients to continually follow recommended bladder and bowel care programs to decrease complications.

Renal physiology of pregnancy

Pregnancy involves remarkable orchestration of physiologic changes. The kidneys are central players in the evolving hormonal milieu of pregnancy, responding and contributing to the changes in the environment for the pregnant woman and fetus. The functional impact of pregnancy on kidney physiology is widespread, involving practically all aspects of kidney function. The glomerular filtration rate increases 50% with subsequent decrease in serum creatinine, urea, and uric acid values. The threshold for thirst and antidiuretic hormone secretion are depressed, resulting in lower osmolality and serum sodium levels. Blood pressure drops approximately 10 mmHg by the second trimester despite a gain in intravascular volume of 30% to 50%. The drop in systemic vascular resistance is multifactorial, attributed in part to insensitivity to vasoactive hormones, and leads to activation of the renin-aldosterone-angiostensin system. A rise in serum aldosterone results in a net gain of approximately 1000 mg of sodium. A parallel rise in progesterone protects the pregnant woman from hypokalemia. The kidneys increase in length and volume, and physiologic hydronephrosis occurs in up to 80% of women. This review will provide an understanding of these important changes in kidney physiology during pregnancy, which is fundamental in caring for the pregnant patient.

Anatomic and Functional Changes of the Upper Urinary Tract During Pregnancy

An appreciation of the maternal physiologic adaptations that occur in the renal system during pregnancy is fundamental to the understanding and proper clinical management of normal pregnancy, renal disorders in the gravid patient, and pregnancy-specific conditions such as pre-eclampsia. In this article, the authors first address the anatomic changes that occur in the upper urinary tract in normal pregnancy, followed by the dramatic alterations in maternal renal hemodynamics and glomerular filtration. They also briefly discuss renal handling of various substrates in pregnancy, including protein, uric acid, and glucose. An understanding of these changes is important and relevant to the clinician caring for pregnant women.

Urinary tract infections in pregnancy

Although pregnancy does not increase the prevalence of ASB in women, it does enhance the progression rate from asymptomatic to symptomatic disease. Furthermore, ASB is associated with preterm delivery. Given the fact that identification and eradication of ASB in pregnant women can lower the likelihood of pyelonephritis and prevent preterm delivery, every gravida should be systematically screened for ASB and appropriately treated. In the authors' opinion, a first-trimester urine culture remains the screening test of choice; reliance on symptoms to prompt screening is inadequate because the state of pregnancy can provoke frequency and nocturia. Multiple antibiotic regimens for ASB are safe during pregnancy and effective.

Detection, significance, and therapy of bacteriuria in pregnancy. Update in the managed health care era

Profound physiologic and anatomic changes of the urinary tract during pregnancy contribute to the increased risk for symptomatic urinary tract infection in women with bacteriuria. Asymptomatic bacteriuria is the major risk factor for developing symptomatic UTIs during pregnancy and may be associated with adverse effects on maternal and fetal health. Because most symptomatic UTIs develop in women with bacteriuria earlier in pregnancy, treatment of bacteriuria is undertaken to prevent symptomatic infections. All pregnant women should be screened at the first antenatal visit, which is reliably and inexpensively done with a dipstick culture. Short-course therapy should be given to women with bacteriuria and clearance of bacteriuria should be documented after therapy is complete. Failure to eliminate bacteriuria with repeated therapy or recurrence with the same organism is indicative of renal parenchymal infection or a structural abnormality. All women with persistent bacteriuria or recurrent infection should have follow-up cultures and a urologic evaluation after delivery.

Obstructive acute renal failure by a gravid uterus: a case report and review

Acute renal failure caused from an obstruction by the gravid uterus is a rare complication of pregnancy. Only 13 cases have been reported. We report a case of obstructive acute renal failure in a patient at 34 weeks' gestation with a twin pregnancy complicated by polyhydramnios. The serum creatinine peaked at 1,078 mumol/L (12.2 mg/dL), higher than in the previously reported patients. The striking feature of her clinical course was the immediate resolution of anuria following amniotomy, thus avoiding the need for dialysis, ureteral stenting, or immediate surgical delivery. This patient illustrates the potential importance of increased uterine pressure on the ureters as a cause of significant obstructive renal failure during pregnancy.

Epidemiology, natural history, and management of urinary tract infections in pregnancy

The urinary tract undergoes profound physiologic and anatomic changes during pregnancy that facilitate the development of symptomatic UTIs in women with bacteriuria. Although the adverse effects of asymptomatic bacteriuria on maternal and fetal health continue to be debated, it is clear that asymptomatic bacteriuria is the major risk factor for developing symptomatic UTI and that symptomatic infections are associated with significant maternal and fetal risks. Because the majority of symptomatic UTIs develop in women with bacteriuria earlier in pregnancy, treatment of bacteriuria is undertaken to prevent symptomatic infections. All women should be screened at the first antenatal visit, which is reliably and inexpensively done with a dipstick culture. Short-course therapy is as effective as prolonged therapy and should be followed with a repeat culture to document clearing of the bacteriuria. Failure to eliminate bacteriuria with repeated therapy or recurrence with the same organism is indicative of renal parenchymal infection or a structural abnormality. All women with persistent bacteriuria or recurrent infection should have follow-up cultures and a complete urologic evaluation after delivery.

Management of acute hydronephrosis of pregnancy by ureteral stenting: risk of stone formation

Acute hydronephrosis of pregnancy has long been managed with ureteral stenting. Although many articles have been published recently concerning stent incrustation none has addressed the etiology. We report a case of accelerated incrustation due to the hypercalciuric state of pregnancy. We propose conservative management with hydration, calcium restriction and close monitoring for infections and stone debris. Antibiotic suppression and stent changes should not be used routinely but rather they should be individualized.