Potter syndrome also known as Potter sequence, is a rare condition characterized by the physical characteristics of a fetus that develop when there is too little amniotic fluid in the uterus (oligohydramnios) during pregnancy. Insufficient amounts of amniotic fluid during pregnancy is called oligohydramnios; the absence of amniotic fluid is called anhydramnios. Amniotic fluid supports, cushions, and protects a developing fetus. When there is too little amniotic fluid normal pressure that is exerted on the fetus during pregnancy can cause certain physical features such as distinctive facial features (Potter facies), which may include a flattened nose, recessed chin, skin folds covering the corners of the eyes (epicanthal folds), and low-set abnormal ears or skeletal abnormalities. Other associated features may include eye malformations and heart defects. When oligo-anhydramnios is present from early in pregnancy, the lungs are also underdeveloped (pulmonary hypoplasia), which can lead to severe breathing difficulties. Most often, Potter’s syndrome is caused by absence of both kidneys (bilateral renal agenesis). This is sometimes referred to as classic Potter syndrome. Potter syndrome can also result from other conditions including polycystic kidney disease, malformed (dysplastic), failure of the kidneys to develop (bilateral renal agenesis), obstructive uropathy in which urine cannot be voided from the bladder and builds up within the kidneys, prune belly syndrome and rupture of membranes surrounding the baby. Sometimes, later during gestation, there may be amniotic fluid leakage; this will not lead to Potter syndrome. Potter syndrome is an extremely serious condition and is often fatal at or shortly after birth, mainly due to the pulmonary hypoplasia.
Potter syndrome is a rare disorder, and the exact incidence or prevalence is unknown. The main cause of Potter syndrome, bilateral renal agenesis, occurs in approximately 1 in 5,000 fetuses and accounts for about 20% of Potter syndrome cases. The incidence or prevalence of other causes are unknown. Overall, estimates for the incidence or prevalence of Potter syndrome range from 1 in 4,000 to 10,000 births. A couple studies have shown that male newborns are affected more often than female newborns, probably due to the obstructive uropathy that is seen more often in males.
The underlying cause of Potter syndrome is often undetermined, but it may be genetic in some cases. The inheritance pattern depends on the specific genetic cause. Diagnosis is based on ultrasound findings or the presence of characteristic symptoms such as kidney malfunction and difficulty breathing. Treatment depends on the underlying cause of Potter syndrome.
Potter syndrome causes
The most common underlying cause of Potter syndrome is absence, underdevelopment or malformation of the kidneys. Absence of both kidneys (bilateral renal agenesis) is the most common condition associated with Potter syndrome. The kidneys produce urine, which makes up the major part of the amniotic fluid, which supports, cushions and protects a developing fetus. Because there is not enough amniotic fluid to protect the fetus, the pressure a fetus undergoes while developing within the uterus that normally does not cause any problems can cause a variety of physical features including distinctive facial features (Potter facies), skeletal abnormalities, and other complications. Amniotic fluid is also essential for the proper development of the lungs. Absence of amniotic fluid, especially in the first half of gestation, will result in underdevelopment of the lungs (pulmonary hypoplasia) as well.
After approximately 16 weeks of pregnancy, the amount of amniotic fluid (fluid that surrounds the baby) depends on how much urine the developing baby is producing. In normal development, the baby continuously swallows amniotic fluid, which is then processed by the kidneys and excreted as urine. Babies with Potter sequence have a problem with the kidneys or urinary tract that is preventing them from producing the correct amount of urine. This causes there to be a low amount of amniotic fluid (oligohydramnios).
Potter syndrome can also result from autosomal recessive polycystic kidney disease, malformation of the kidneys, a rare disorder characterized by absence of the abdominal muscles (prune belly syndrome), certain chromosomal disorders, and obstructive uropathy, in which urine cannot be voided from the body and builds up into the kidneys. Sometimes, Potter syndrome results from prolonged rupture of the amniotic membranes, which allows amniotic fluid to leak out. This usually seen when the rupture occurs early in a pregnancy and goes undetected for a long period of time.
In most instances, Potter syndrome occurs sporadically for no known reason. However, sometimes the underlying cause, such as certain kidney abnormalities, may be genetic. If related to a genetic condition, this can occur spontaneously without a family history of the condition, or the genetic condition could have been inherited and genetic counseling is recommended.
Potter syndrome symptoms
The signs and symptoms of Potter syndrome can vary from one newborn to another. However, the condition is associated with severe complications affecting the developing fetus and is often fatal at or shortly after birth. When caused by bilateral agenesis of the kidneys, Potter syndrome is not compatible with life. Potter syndrome due to other causes is also often fatal at or shortly after birth, but there is an increased chance for survival. Infants who do survive the newborn period generally experience chronic lung disease and chronic kidney failure.
Because of the lack of amniotic fluid to protect the developing fetus, normal pressure from the uterine walls can affect the growth and development of the fetus. Such pressure may cause distinctive facial features including a recessed chin; a flattened, depressed bridge of the nose; eyes that are spaced further apart than normal (hypertelorism); low-set ears that lack cartilage (Potter ears); abnormally prominent skins folds in the inner corners of the eyes (prominent epicanthal folds); and a crease beneath the lower lips. This collection of facial features is sometimes referred to as “Potter facies.”
There is usually a lack of urine creation and output because of kidney abnormalities. Absence (agenesis) of both kidneys is the most common defect associated with Potter syndrome. The kidneys can also be malformed (dysplastic), or damaged because of a larger syndrome affecting the kidneys such as polycystic kidney disease, a group of rare disorders characterized by the development of numerous cysts within the kidneys.
The lungs may be underdeveloped (hypoplastic) and most newborns experience severe breathing complications after birth (respiratory distress).
Sometimes there are abnormalities in the development of the arms and legs, lack of formation of half of the spine (hemivertebrae), absence of the lower portion of the spine (sacral agenesis), congenital heart defects, or abnormalities of the eyes such as cataracts, or displacement or dislocation (prolapse) of the lenses of the eyes.
Infants with Potter syndrome are often born prematurely and are small for their gestational age, which means they are smaller than would normally be expected for how far along the pregnancy is.
Potter syndrome diagnosis
A diagnosis of Potter syndrome is based upon identification of characteristic symptoms, a detailed patient history, a thorough clinical evaluation and certain specialized tests. If not detected before birth (prenatally), then lack of urine production, specific (facial) features or difficulty breathing may be signs of Potter syndrome.
Clinical testing and workup
A routine specialized imaging technique called a fetal ultrasound may detect Potter syndrome before birth. A fetal ultrasound uses reflected sound waves to create an image of the developing fetus and can reveal a lack of amniotic fluid. An ultrasound can also show abnormalities or absence of the kidneys. Swelling of the kidneys due to a buildup of urine (hydronephrosis), which can occur when there is an obstruction of the urinary tract, can also be seen on an ultrasound.
X-ray examination of the lungs after birth may show underdevelopment of the lungs.
Physicians may run blood and urine tests to determine the levels of electrolytes, enzymes and other substances that may be elevated or decreased in Potter syndrome. These tests can aid in obtaining a diagnosis of the condition.
An echocardiogram, which is a test that uses sound waves to create a picture of the heart, may be conducted to detect congenital heart defects potentially associated with this condition.
Potter syndrome treatment
There is no treatment for Potter syndrome due to bilateral absence of the kidneys, which is not compatible with life. Efforts should be made to ensure the entire family receives coping support and grief counseling. Genetic counseling is recommended. Psychosocial support for the entire family is essential as well.
Newborns with Potter syndrome due to other causes will usually need assistance to breath (mechanical ventilation). Resuscitation may also be necessary. Decisions whether to resuscitate are made in close consultation with the parents, physicians and entire medical team.
In some newborns who have partially functioning kidneys and sufficient lung function, dialysis may be needed, which is an intensive and troublesome therapy in newborns.
Children who survive Potter syndrome require management of the following:
- Pulmonary hypoplasia: Mechanical ventilation and chest tube placement may be indicated for ventilatory support and for the treatment of spontaneous pneumothorax.
- Renal function: This is assessed with imaging studies and calculation of the glomerular filtration rate (GFR) by using the serum creatinine concentration.
Management of renal failure may be required.
- Nutrition: Adequate nutrition is required. Nasogastric feeding may be indicated in infants.
- Electrolyte abnormalities such as hypocalcemia and hyperphosphatemia can be treated with medications, including calcium carbonate and vitamin D.
- Anemia is treated with oral or parenteral iron and erythropoietin stimulating agents.
- Children may have hypertension from either fluid-related causes or activation of the renin-angiotensin system. Antihypertensives that may be given include diuretics, beta-blockers, calcium channel blockers, and ACE inhibitors.
- Growth: The use of growth hormone is indicated in children with a low GFR who do not grow at a healthy rate.
Potter syndrome prognosis
Potter syndrome a very serious condition. Most of the time it is deadly. The short-term outcome depends on the severity of lung involvement. Long-term outcome depends on the severity of kidney involvement. Children with Potter syndrome due to conditions such as infantile polycystic kidney disease, multicystic dysplastic kidney, hypoplastic kidney, Prune-Belly syndrome, and rupture of membranes during gestation have a higher survival rate than children with Potter syndrome due to other conditions.