Congenital Giant Hydronephrosis: A Rare Cause for Upper Abdominal Mass in the Newborn
A 20-year-old primigravida with no known co-morbidity was referred to the radiology department for a routine antenatal USG at 20 weeks 3 days of gestation by her last menstrual period. USG revealed appropriate fetal growth corresponding to gestational age. The left kidney of the fetus demonstrated dilated pelvis with antero-posterior (AP) dimension measuring 8.6 mm []. Follow-up USG was performed 1 month later, which revealed the progression of hydronephrosis with AP dimension of pelvis measuring 19 mm along with dilatation of calyces (SFU grade III, ]. Amniotic fluid was normal in quantity. No other congenital anomaly was detected at this point. She had a spontaneous preterm (at 35 weeks) vaginal delivery of a low-birth weight (1960 g) male baby. At birth, the neonate had mild respiratory distress, which settled over the next few hours with conservative treatment and did not require any active resuscitation. The baby was slightly irritable with visible distension of the upper abdomen []. There was a palpable lump across the entire upper abdomen (epigastric, supra-umbilical, both hypochondrium and both flanks). The neonate underwent an urgent USG, which revealed hydronephrotic left kidney (SFU grade IV) with grossly distended renal pelvis (40 mm × 65 mm × 72 mm, AP × TR × CC, ~187 cc) extending across the midline to reach the right hypochondrium and flank []. The right kidney and urinary bladder were normal on USG. Hematological parameters including blood urea, serum creatinine and electrolytes were within normal limits. Initially, the neonate was managed conservatively as the vital parameters, including urine output, were normal. Micturating cysto-urethrogram was performed at a later date, and was found to be normal. The child underwent a radionucleide dynamic renogram at 2 months of age, which revealed dilated obstructed pelvis with compromised function of the left kidney. The left kidney demonstrated reduced perfusion with glomerular filtration rate of 74% and a split function of 37%. No excretion was noted on the left side during the dynamic renogram. Prolonged excretion was noted on the right side. A dimercapto succinic acid renal scan revealed enlarged left kidney with markedly reduced tracer concentration and persistent excretion through the right kidney []. The child was operated (pyeloplasty done) at the end of the 4th month. Intraoperatively, the findings of antenatal as well as post-natal USG were confirmed. Left renal pelvis was ballooned out and was reaching to the right side across the midline with thinned-out renal parenchyma. The child has been followed-up for 18 months and has been doing well. Follow-up USG revealed postoperative status with residual dilated PC system of the left kidney.