Polyhydramnios is a medical condition describing an excess of amniotic fluid in the amniotic sac. It is seen in about 1% of pregnancies. It is typically diagnosed when the amniotic fluid index (AFI) is greater than 24 cm. There are two clinical varieties of polyhydramnios: chronic polyhydramnios where excess amniotic fluid accumulates gradually, and acute polyhydramnios where excess amniotic fluid collects rapidly. The opposite to polyhydramnios is oligohydramnios, not enough amniotic fluid. Presentation
Associated conditions
Fetuses with polyhydramnios are at risk for a number of other problems including cord prolapse, placental abruption, premature birth and perinatal death. At delivery the baby should be checked for congenital abnormalities. Causes
In most cases, the exact cause cannot be identified. A single case may have one or more causes, including intrauterine infection (TORCH), rh-isoimmunisation, or chorioangioma of the placenta. In a multiple gestation pregnancy, the cause of polyhydramnios usually is twin-to-twin transfusion syndrome. Maternal causes include cardiac problems, kidney problems, and maternal diabetes mellitus, which causes fetal hyperglycemia and resulting polyuria (fetal urine is a major source of amniotic fluid). A recent study distinguishes between mild and severe polyhydramnios and showed that Apgar score of less than 7, perinatal death and structural malformations only occurred in women with severe polyhydramnios. In another study, all patients with polyhydramnios, that had a sonographically normal fetus, showed no chromosomal anomalies. (M/C for polyhydramnio is fetal anomalies Williams Obstetrics, 24th Edition – Cunningham,  Leveno, Bloom et al.
Inheritance within families
In most of the families reported so far, tetra-amelia syndrome appears to have an autosomal recessive pattern of inheritance. This means the defective gene responsible for the disorder is located on an autosome , and two copies of the defective gene (one inherited from each parent) are required in order to be born with the disorder. The parents of an individual with an autosomal recessive disorder both carry one copy of the defective gene, but usually do not experience any signs or symptoms of the disorder. Epidemiology
Tetra-amelia syndrome has been reported in only a few families worldwide. According to a 2011 study by Bermejo-Sanchez, amelia – that is, the lacking of one or more limbs – occurs in roughly 1 out of every 71,000 pregnancies. People with tetra-amelia syndrome
Joanne ORiordan of Millstreet, Cork, Ireland. At the age of 16 she addressed the United Nations in New York. She appeared before the International Telecommunication Union’s conference ‘Girls in Technology’, receiving a standing ovation after delivering the keynote speech. Hirotada Ototake
Nick Vujicic, founder of Life Without Limbs. Prince Randian
Violetta (entertainer)
Kent Bell (1965-2015) of Jacksonville, FL, scoreboard operator and disabled rights advocate, appeared on Oprah Winfrey show and in numerous print articles over the course of his life. Rob Mendez, varsity football team offensive coordinator at Francis Parker School (San Diego). Christian Arndt of Germany, media presenter. References
External links

"Tetra-amelia syndrome - Genetics Home Reference". U.S. National Library of Medicine. Retrieved 2009-01-09.