LAUSR

Bartter syndrome is a rare autosomal recessive renal tubular disorder, first described by Frederic Bartter in 1962. The primary pathogenic mechanism is defective transepithelial chloride reabsorption in the thick ascending limb of the loop of Henle. Several mutations are on the basis of the syndrome, with the classical one being CLCNKB/1p36. The disease is characterized by hypokalemia, metabolic alkalosis, and secondary hyperaldosteronism with normal to low blood pressure due to renal loss of sodium. Antenatal Bartter syndrome in its severe form has its onset in utero and awareness to the condition is imperative for early diagnosis. The typical features in utero may include early onset maternal polyhydramnios, intrauterine growth restriction, and preterm birth. Clinical postnatal features may include polyuria, episodes of dehydration, recurrent vomiting, and failure to thrive. A 22-year-old G3P2 patient was referred to our unit with polyhydramnios. Obstetrical history included 2 vaginal deliveries, the first at 32 weeks that followed prenatal diagnosis of severe polyhydramnios. The child was further diagnosed with Bartter Syndrome. Second delivery was vaginal and uneventful and occurred at 39 weeks of gestation with a healthy child. During the relevant pregnancy, optimal dating was attained at 10 weeks of gestation and prenatal course was normal until 26 weeks of gestation, when mild polyhydramnios was suspected, for which she was referred to our unit, and presented at 28 weeks of gestation. On prenatal ultrasound, a female fetus was seen with appropriate for gestational age weight estimation. Amniotic fluid index (AFI) was 33 cm. Abdominal circumference was normal; however, the bowel was prominent and mildly dilated with an edematous bowel wall (Figure 1). The patient refused any genetic and chromosomal workup or intervention and elected to continue regular prenatal care. She presented at 32 weeks of gestation with preterm premature rupture of the membranes (PPROM). On ultrasound, although PPROM, AFI was 53 cm, biophysical profile was normal, and she progressed to full cervical dilatation and uneventfully delivered a 1900 g baby girl with excellent Apgar score. By the age of 6 days, the newborn lost 20% of her birth weight, mainly due to polyuria (5 mL/kg per hour). At this time, laboratory blood analysis indicated prerenal azotemia and hyponatremia (118 mEq/dL) that was managed with Intravenous (IV) fluids and hypertonic saline supplements. Blood gas analysis showed the following: pH of 7.48, bicarbonate of 34 mg/dL, PCO2 of 44 mm Hg, and chloride of 90 mm Hg. Metabolic alkalosis was not resolved following treatment of dehydration. Following the above, a diagnosis of chloride-resistant metabolic alkalosis has been made, probably due to Bartter syndrome. At present, the patient declines genetic confirmation. Several reports offered different prenatal diagnostic criteria for Bartter syndrome. The only ultrasonic diagnostic parameter ever reported and appears in almost all the cases as well as our report includes polyhydramnios that led to prenatal diagnosis through amniotic fluid analyses. Prominent, dilated, and edematous bowel loops are referred to as signs of bowel or pseudo-bowel obstruction. In utero, bowel obstruction may occur due to a large number of conditions. The most common etiology is mechanical obstruction, most frequently due to ileo-jejunal atresia or cystic fibrosis-related meconium ileus. Functional, nonobstructive, dilated small bowel with polyhydramnios has been described in congenital chloride diarrhea, in fetal paralytic ileus secondary to maternal benzodiazepam ingestion and, without polyhydramnios, as a manifestation of transient fetal bowel ischemia. To the best of our knowledge, ours is the first report of prenatal diagnosis of Bartter syndrome based on prenatal ultrasound feature other than polyhydramnios. Accordingly, we offer another differential diagnosis to nonobstructive bowel dilatation in utero. We assume that this typical appearance of the bowel was secondary to hypocalcemia causing in utero paralytic ileus. FIGURE 1 Dilated edematous bowel in Bartter syndrome Received: 14 July 2018 Revised and accepted: 21 August 2018 DOI: 10.1002/jcu.22642