Congenital Disorders of the Upper Tracts Flashcards
What are the features of Potter syndrome?
- Compressed facies
- Low-set ears
- Limb contractures
What is the etiology of Potter syndrome?
Potter syndrome is a series of changes that occur in a fetus secondary to extreme oligohydramnios. This can be from an inability to produce urine such as renal agenesis, bilateral multicystic renal dysplasia, or juvenile polycystic kidneys. Another reason for oligohydramnios is an impaired ability to void such as posterior urethral valves.
What is the embryological basis and the characteristic findings of the Mayer-Rokitansky-Küster-Hauser (MRKH) syndrome and how does it usually present?
Müllerian agenesis, which leads to a congenital absence of the middle and upper third of the vagina with variable uterine and fallopian tube defects. In approximately one-third of these cases, upper tract anomalies can also be found. These include renal agenesis or hypoplasia, renal ectopia, pelvic kidney, and horseshoe kidney. Skeletal abnormalities (usually vertebral) occur in 10% to 20%. There are 2 types of MRKH syndrome. Type A (typical) has symmetric remnant müllerian muscular buds and normal fallopian tubes and Type B (atypical) is associated with asymmetric buds and abnormal fallopian tubes. Although Type B has been deemed “atypical,” it is actually more common than Type A. Renal and skeletal abnormalities occur only in Type B MRKH syndrome. The most common presentation is primary amenorrhea.
Patients found to have a missing vas deferens during an infertility workup should be screened for what abnormality and how?
Ipsilateral renal agenesis that can be confirmed on renal ultrasound.
What is the incidence of unilateral renal agenesis?
Approximately 1:1400 births.
What is the incidence of bilateral renal agenesis?
Approximately 1:4000 with a ratio of male to female of 2.5:1. This is a lethal condition associated with a number of genetic syndromes.
What is the long-term prognosis for a baby born with a solitary kidney?
If there are no other associated anomalies, prognosis is good. However, contralateral reflux is found in one-third of children with renal agenesis and is not uncommon in patients with multicystic dysplastic kidney. Patients with solitary kidneys are at increased risk for developing proteinuria, hypertension, and renal insufficiency over the course of his or her lifetime; however, the patient’s life expectancy is normal.
What is the most common additional urologic abnormality associated with a horseshoe kidney?
The incidence of horseshoe kidney is 1:400 to 1:1800 with a male predominance of 2:1. Up to 35% of patients with a horseshoe kidney have evidence of significant ureteropelvic junction obstruction, more commonly on the left. Patients with a horseshoe kidney are also at a greater risk of vesicoureteral reflux (VUR) with reported rates of 80%.
Is there an increased cancer risk with fused kidneys?
There is a 1.5-fold to 8-fold increased risk of Wilms tumor in these kidneys. It is unclear at this time if there is an increased risk of adult urologic cancers in fused kidneys; however, some studies demonstrate an increased risk of transitional cell carcinoma in these patients.
The cephalad migration of a horseshoe kidney is limited by what structure?
The inferior mesenteric artery.
What is the normal direction of rotation of the human kidney as it ascends out of the pelvis?
The kidney normally rotates 90° ventromedially during ascent. Therefore, the renal pelvis, which was originally directed anteriorly, becomes directed medially.
True/False: most crossed ectopic kidneys are fused with their mate.
True. Approximately 90% of crossed ectopic kidneys are fused with a normally placed mate.
What is the incidence of antenatal hydronephrosis?
In the United States, more than 600,000 fetal ultrasounds are performed. Of these, 0.2% to 2% will detect antenatal hydronephrosis. Postnatal ultrasound demonstrates that 66% to 75% persist after birth.
What is the most common cause of hydronephrosis in the fetal kidney?
Ureteropelvic junction obstructions are the etiology of 60% to 80% of cases of persistent fetal hydronephrosis. VUR is responsible for 25% to 35% of postnatal hydronephrosis.
True/False: most cases of prenatally diagnosed ureteropelvic junction obstruction require urgent surgical intervention following delivery.
False. Debate continues surrounding the management of prenatally diagnosed ureteropelvic junction obstructions. Most often surgery is not necessary or can be performed on an elective basis after an appropriate evaluation and period of observation.
