Potter sequence

Overview

Potter sequence, also known as Potter syndrome, is a rare and often fatal condition that results from a significant lack of amniotic fluid (oligohydramnios) during pregnancy. The condition leads to a series of physical abnormalities collectively known as the Potter facies, as well as underdeveloped lungs (pulmonary hypoplasia) and limb deformities. It is classified as a sequence rather than a syndrome because the primary problem—insufficient amniotic fluid—triggers a cascade of secondary developmental issues. Potter sequence is often caused by kidney abnormalities that reduce fetal urine output, which is a key component of amniotic fluid in the second and third trimesters.

Causes

Potter sequence is most commonly caused by conditions that impair or eliminate fetal urine production, leading to severe oligohydramnios. Major underlying causes include:

• Bilateral renal agenesis: Complete absence of both kidneys, the most classic and fatal cause

• Polycystic kidney disease (autosomal recessive): Enlarged, non-functioning kidneys

• Obstructive uropathy: Blockages in the urinary tract such as posterior urethral valves, preventing urine from exiting the fetus

• Renal hypoplasia or dysplasia: Poorly developed or malformed kidneys

• Chronic amniotic fluid leak: Due to premature rupture of membranes (PROM)

Since fetal urine production is a major contributor to amniotic fluid volume, disruption of kidney function or urinary flow leads to severe oligohydramnios, which impairs normal fetal growth and lung development.

Symptoms

The symptoms of Potter sequence are evident in the physical anomalies observed at birth and are a result of the fetus being compressed in a low-fluid environment during gestation. Common features include:

Facial Features (Potter Facies)

• Flattened nose

• Low-set ears

• Receding chin (micrognathia)

• Epicanthal folds and wide-set eyes

Other Physical and Systemic Features

• Pulmonary hypoplasia (underdeveloped lungs), often leading to respiratory failure at birth

• Limb deformities such as clubfoot or joint contractures

• Growth restriction and a small body size

• Abnormal genitalia in some cases

The severity of these features may vary depending on the underlying cause and the duration of oligohydramnios during gestation. Pulmonary hypoplasia is the most life-threatening consequence.

Diagnosis

Potter sequence can often be diagnosed prenatally or immediately after birth. Diagnostic approaches include:

• Ultrasound during pregnancy: Can detect oligohydramnios, absent or malformed kidneys, and abnormal fetal positioning

• Fetal MRI: May be used to evaluate lung development and kidney structure in more detail

• Genetic testing: Especially in cases of suspected autosomal recessive polycystic kidney disease or other inherited renal anomalies

• Postnatal imaging: Such as ultrasound or X-rays to confirm renal agenesis and assess lung and limb abnormalities

• Autopsy (if fatal): Provides definitive diagnosis and insight into the underlying anatomical defects

Treatment

Treatment options for Potter sequence depend on the underlying cause and the severity of associated abnormalities. In cases of bilateral renal agenesis, the condition is typically fatal. For other causes, some interventions may be possible:

Prenatal Interventions

• Amnioinfusion: Injection of saline into the amniotic sac to increase fluid levels and promote lung development

• Fetal surgery: Experimental procedures to relieve urinary tract obstructions in utero

Postnatal Management

• Neonatal intensive care support, particularly for respiratory failure

• Dialysis for newborns with non-functioning kidneys

• Possible kidney transplantation in surviving infants with severe renal disease

• Orthopedic interventions for limb deformities

Despite these efforts, many infants with Potter sequence do not survive, particularly those with bilateral renal agenesis and severe pulmonary hypoplasia.

Prognosis

The prognosis of Potter sequence is generally poor and depends heavily on the underlying cause and the severity of pulmonary hypoplasia. Bilateral renal agenesis is incompatible with life, with affected infants often dying within hours of birth due to respiratory failure. Cases resulting from obstructive uropathy or other treatable conditions may have a better prognosis if identified early and managed with advanced neonatal care and surgical intervention. Long-term survival may require chronic dialysis and kidney transplantation, along with ongoing multidisciplinary care. Early diagnosis and supportive care are crucial for any possibility of a favorable outcome.