Potter’s Syndrome, often called the Potter sequence, is a severe and rare congenital condition impacting fetal development during gestation. This syndrome is a chain of events where the failure of one organ system leads directly to developmental problems in others. The condition is characterized by a distinctive physical appearance and is associated with life-threatening complications.
Renal Agenesis and Oligohydramnios
The sequence of events begins with a failure of the fetal urinary system, most commonly due to bilateral renal agenesis (BRA), meaning both kidneys fail to develop. While severe kidney disease or urinary tract obstruction can also initiate the process, the absence of both kidneys represents the classic and most severe cause. Kidneys normally begin to function and produce urine around the 16th to 20th week of pregnancy.
After the first trimester, fetal urine production is the main source of the amniotic fluid surrounding the developing fetus. When the kidneys are absent or non-functional, the volume of amniotic fluid drops significantly, a condition known as oligohydramnios. This low volume of fluid is the intermediate step that directly causes the physical features associated with the syndrome. The lack of fetal urine also means the fetus cannot cycle the amniotic fluid, which is important for lung growth.
The Distinct Features of the Potter Sequence
The absence of sufficient amniotic fluid removes the protective cushion necessary for normal fetal growth and movement within the uterus. This exposes the fetus to mechanical compression from the uterine wall, resulting in a characteristic set of physical abnormalities. These features are collectively known as the Potter sequence, regardless of the initial cause of the fluid deficiency. The most severe consequence of oligohydramnios is pulmonary hypoplasia, or the underdevelopment of the lungs.
Normal lung development requires the fetus to circulate amniotic fluid to physically stretch the airways and stimulate lung tissue growth. Without this fluid, the lungs remain small and immature, unable to take in enough oxygen after birth. This respiratory failure is the primary cause of mortality in infants with the syndrome. The mechanical compression also affects the face and limbs, leading to features often termed Potter facies.
These facial characteristics include widely separated eyes, a flattened nasal bridge, low-set ears, and a receding chin, all caused by the sustained pressure of the uterine wall. The restricted space can also lead to orthopedic issues, such as limb positioning defects like club feet or bowed legs. The severity of these features is directly related to how early and profoundly the oligohydramnios began during the pregnancy.
Diagnosis and Medical Outlook
Potter’s Syndrome is most often identified during prenatal care, typically through a routine ultrasound examination. The sonogram will show severe oligohydramnios, and a detailed scan will fail to visualize the fetal kidneys or urinary bladder. While the diagnosis can be suggested prenatally, it is confirmed after birth by physical examination and the absence of urine output.
The medical outlook for classic Potter’s Syndrome resulting from bilateral renal agenesis is uniformly poor. Due to the severity of pulmonary hypoplasia, most affected infants are stillborn or die shortly after birth from respiratory distress. For cases where oligohydramnios is caused by a treatable factor, such as a urinary tract obstruction, the prognosis can be slightly better with timely intervention. Families with a history of the condition may be advised to seek genetic counseling, as some causes of renal agenesis have a hereditary pattern.