Hydronephrosis and Hydroureter Follow-up

Updated: Dec 16, 2020
  • Author: Dennis G Lusaya, MD; Chief Editor: Bradley Fields Schwartz, DO, FACS  more...
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Further Outpatient Care

Once the diagnosis is made and treatment is performed, follow-up imaging studies are necessary to assess for resolution of the hydronephrosis and hydroureter. Additionally, laboratory studies of renal function should be performed, to assess the recovery of renal function.

For ultrasonography follow-up, fetuses with mild hydronephrosis should have follow-up ultrasonography in the third trimester (32-34 wk gestation). The interval for follow-up examination and management is dictated by the initial findings and the amount of amniotic fluid. Those with resolution have a low risk of clinically significant pathology and do not need further antenatal or postnatal evaluation. Serial follow-up ultrasonography is indicated for fetuses with the following:

  • Moderate or severe hydronephrosis

  • Bilateral involvement

  • Progression and/or persistence of hydronephrosis

  • Normal amniotic fluid volume: Fetuses with unilateral involvement and normal amniotic fluid volume should have repeat prenatal ultrasonography examination at 32-34 weeks of gestation to evaluate and guide postnatal evaluation.

  • Bilateral hydronephrosis and normal amniotic fluid volume: These patients should have repeat ultrasonography examination 2-3 weeks after diagnosis to evaluate for progression and amniotic fluid volume. Follow-up examinations are determined according to the serial ultrasonography results.

For follow-up in older children with hydronephrosis, most protocols recommend serial monitoring with ultrasound and diuretic renography. Indications for surgery include worsening of hydronephrosis, lithiasis, recurrent infections, or deterioration of renal function. Although diuretic renography remains the gold standard for the diagnosis of obstructive hydronephrosis, the use of color Doppler ultrasound to determine hydronephrosis grading and the absence of ureteral jets offers an accurate and noninvasive option that can limit the need for renography. [43]


Further Inpatient Care

Monitor patients for postobstructive diuresis. This is a marked polyuria observed after relief of an obstructed system.

Patients who are most likely to experience postobstructive diuresis present with chronic obstruction, edema, congestive heart failure, hypertension, weight gain, and azotemia. Clinically significant postobstructive diuresis is usually seen only in the setting of prior bilateral obstruction or, similarly, a unilateral obstruction of a solitary functioning kidney.

This postobstructive diureses can lead to a marked diuresis with the wasting of sodium, potassium, phosphate, and the divalent cations. Management involves avoiding severe volume depletion, hypokalemia, hyponatremia, hypernatremia, and hypomagnesemia.

Volume or free-water replacement is appropriate only when the salt and water losses result in volume depletion or a disturbance of osmolality. In many cases, excessive volume or fluid replacement prolongs the diuresis and natriuresis. An appropriate starting fluid for replacement is 0.45% saline. During this period, vital signs, volume status, urine output, and serum and urine chemistry and osmolality should be monitored.

Postobstructive diuresis is usually self-limited. It usually lasts for several days to a week but may, in rare cases, persist for months.

In fetuses with severe oligohydramnios and documented lung maturation, early delivery has been suggested. Although no data document improved renal outcome with early delivery, early delivery may be indicated to reduce the risk of other adverse outcomes from oligohydramnios, such as umbilical cord compression.



Postobstructive diuresis refers to polyuria that occurs after relief of obstruction. Patients with edema, congestive heart failure, hypertension, weight gain, and azotemia are most likely to exhibit this condition. It is more common in patients with chronic obstruction. Postobstructive diuresis is usually clinically significant only in patients whose obstruction involves both kidneys or a unilateral obstruction of a solitary functioning kidney.


Patient Education

For patient education resources, see the Kidneys and Urinary System Center, as well as Intravenous Pyelogram.