Weill Cornell Medicine Urology
Weill Cornell Medicine Urology
Prenatal Hydronephrosis

Prenatal Hydronephrosis

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In the United States, 3 million maternal ultrasounds are performed annually with hydronephrosis being the most commonly detected anomaly.

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As hydronephrosis is detected in as many as 42,000 fetuses (1.4%), obstetricians and pediatric urologists alike commonly encounter the diagnosis of prenatal hydronephrosis.

With the use of sonography, dilation of the renal collecting system can be observed, but obstruction cannot be confirmed. However, up to one half of these neonates do not have hydronephrosis on the postnatal ultrasound. The remaining one half with hydronephrosis have a range of diagnoses. The majority (64%) are attributed to ureteropelvic junction (UPJ) obstruction. The remaining 36% are secondary to vesicoureteral reflux, megaureter, or posterior urethral valves. UPJ obstruction refers to a kink or stricture of the collecting system as it begins to leave the kidney to form the ureter. This causes blockage of urine flow and can possibly lead to infections, scarring, and long term damage of the kidney. Reflux is another important condition that is described elsewhere on our website. In short, this refers to a condition that allows for the backflow or reflux of urine up into the kidney from the bladder. If the urine is infected with bacteria, this can also lead to infection, scarring, and damage to the kidneys.

Developmental Physiology

At birth, a sudden increase in total cardiac output and renal vascular resistance occurs. Subsequently, the kidney enters a period of transitional physiology. During the transitional phase, resistance to flow decreases in the renal vasculature, total renal blood flow increases, and the glomerular filtration rate (GFR) doubles. Over the first six months of life the urinary concentrating ability improves exponentially.

Since maturation and development are the key features in the neonatal period, any insults suffered by the kidney during this phase can be profoundly reflected in the ultimate structure and function of the kidney. Ultimately the most morbid sequelae that can result from obstructive uropathy are defects in lung maturation and renal maldevelopment.

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Prenatal Imaging

Despite widespread use of ultrasound, a debate exists in the field of maternal fetal medicine over the required use of gestational (in utero) ultrasound. Clear indications for sonography include discrepancies in fundal height for gestational age, elevated levels of maternal serum alpha fetal protein, and a history of previous pregnancies resulting in congenital anomalies. Regardless of the controversy, when a gestational ultrasound is performed certain basic details must be covered in the examination. These include:

  • Estimation of fetal size and maturity
  • Amniotic fluid volume
  • Standard fetal survey of head, spine, heart, lungs, limbs, and abdomen
  • Assessment of kidneys including position, size, and texture
  • Appearance of ureters and collecting system
  • Bladder volume, wall thickness, and emptying
  • Examination of other pelvic organs
  • Appearance of external genitalia
  • Fetal kidneys can be visualized by the 14th to 15th week of gestation. By the 20th week of gestation, the internal architecture of the kidneys can be assessed. A normal fetal ureter is rarely visualized during ultrasonography. The actual incidence of genitourinary abnormalities on prenatal ultrasound is .2%.

Hydronephrosis is the most common abnormality detected on prenatal ultrasonography. It accounts for about 50% of all prenatally detected defects. When prenatal hydronephrosis is discovered on ultrasound, the finding does not confirm the presence of obstruction. This is due to the extremely elastic nature of the fetal kidney.

Prenatal Hydronephrosis - Risks & Causes

Summary: 

The most common cause of fetal hydronephrosis is ureteropelvic junction (UPJ) obstruction.

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Prenatal Hydronephrosis - Symptoms & Evaluation

Summary: 

In most cases, postnatal evaluation can be performed on an outpatient basis.

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Prenatal Hydronephrosis - Treatment Options

Summary: 

The actual surgical and medical management of post-natal urinary tract obstruction due to UPJ is a controversial entity.

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Physicians & Faculty

Dr. Dix Phillip Poppas, M.D., F.A.A.P., F.A.C.S. | Cornell Urology
AETNA-HMO, AETNA-PPO, Aetna-Weill Cornell POS, Affinity Essential, Affinity Health Plan, Blue Priority Network, CIGNA, EBCBS HMO, EBCBS Pathway X, EBCBS Pathway X Enhanced, EBCBS PPO/EPO, Empire BCBS HealthPlus, Empire BCBS HealthPlus (CHP), Fidelis Care, Health First, Health Insurance Plan of NY (HIP) [Medicaid], Medicaid, Medicare, Oxford Freedom, POMCO, Rockefeller University-CoreSource, VNSNY CHOICE SelectHealth
The Institute for Pediatric Urology

Ardavan Akhavan

M.D.

(212) 746-5361
(212) 746-5361
Aetna-Weill Cornell POS, Blue Priority Network, EBCBS HMO, EBCBS Mediblue, EBCBS Pathway X, EBCBS Pathway X Enhanced, EBCBS PPO/EPO, Fidelis Care, Health First, Medicaid, Medicare, Rockefeller University-CoreSource
The Institute for Pediatric Urology
Dr. Jeremy B. Wiygul, M.D. | Cornell Urology

Jeremy Wiygul

M.D.

(718) 224-2644
(718) 224-2644
AETNA, Affinity (Exchange Products: Essential- Platinum, Gold, Silver, Broze, American Indian, Catastrophic), Amida Care, CIGNA, Consumer Health Network (CHN), Coventry/FirstHealth, EBCBS Pathway X, EBCBS Pathway X Enhanced, Elderplan, Empire BCBS Healthplus (AmeriGroup NY), Fidelis (Excluding Fidelis Exchange and Essential), GHI PPO/CBP/Prem PPO (Emblem Exchange Products: Select Care Bronze, Silver, Gold, Platinum, Basic), Health First (Excluding Leaf Products), HIP (Incl. Comprehealth) (Emblem Exchange Products: Select Care Bronze, Silver, Gold, Platinum, Basic), Local 1199, MagnaCare (Exchange Products: Health Republic Essenital Care, Oscar Edge Plans), Medicare, MultiPlan, Oxford (NY State of Health), Railroad Medicare, United Health Care [Community Plan], VNSNY Choice/VNS FIDA (formerly Select Health), Wellcare (Medicare, Medicaid, CHP, and FHP-exclusing Essential Plan)
Weill Cornell Medicine Urology - Queens

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