Prenatal diagnosis of renal agenesis in a twin gestation.

Bilateral renal agenesis is a lethal congenital anomaly. It appears to be transmitted in a polygenic pattern. The prenatal ultrasound findings consist of severe oligohydramnios, absence of the fetal bladder, and failure to identify fetal kidneys. Twin gestations with renal agenesis have been described in the paediatric literature. We detail a case of a patient with two prior affected pregnancies with bilateral renal agenesis. Her latest pregnancy was diagnosed prenatally, with one fetus with bilateral and the other fetus with unilateral renal agenesis. The ultrasound findings should be differentiated from the stuck twin phenomenon.

A fetus with sirenomelia, omphalocele, and meningomyelocele, but normal kidneys.

Sirenomelia, which has been reported for more than 450 years, is the most severe form of caudal dysplasia. This disorder is classically associated with agenesis or severe dysplasia of the urinary tract. A 27-year-old gravida 3 para 0020 presented at 19 weeks' gestation with monoamniotic twins, one normal and one with sirenomelia. The pregnancy miscarried following invasive diagnostic testing. Autopsy confirmed the findings of sirenomelia, meningomyelocele, omphalocele, persistent cloaca, and two normal kidneys. The abnormalities accompanying sirenomelia appear as a spectrum. The pathogenic theories of sirenomelia are reviewed in light of this case with normal kidneys.