Editing Twin-to-twin transfusion syndrome (section)

===Quintero stages===
A staging system is commonly used to classify the severity of TTTS.<ref>{{cite web |title= Understanding the Stages of TTTS |publisher= UC San Diego |access-date= April 23, 2012 |url= http://health.ucsd.edu/women/child/prenatal/perinatal/fetalsurgery/ttts/Pages/stages.aspx |url-status= dead |archive-url= https://web.archive.org/web/20120410123546/http://health.ucsd.edu/women/child/prenatal/perinatal/fetalsurgery/ttts/Pages/stages.aspx |archive-date= April 10, 2012 |df= mdy-all }}</ref>

'''Stage I''': A small amount of amniotic fluid (oligohydramnios) is found around the donor twin and a large amount of amniotic fluid (polyhydramnios) is found around the recipient twin.

'''Stage II''': In addition to the description above, the ultrasound is not able to identify the bladder in the donor twin.

'''Stage III''': In addition to the characteristics of Stages I and II, there is abnormal blood flow in the umbilical cords of the twins.

'''Stage IV''': In addition to all of the above findings, the recipient twin has swelling under the skin and appears to be experiencing heart failure (fetal hydrops).

'''Stage V''': In addition to all of the above findings, one of the twins has died. This can happen to either twin. The risk to either the donor or the recipient is roughly equal & is quite high in Stage II or higher TTTS.

The Quintero staging does not provide information about prognosis, and other staging systems have been proposed.<ref>{{cite journal|last=Cristina|first=Rossi|title=The Efficacy of Quintero Staging System to Assess Severity of Twin-Twin Transfusion Syndrome Treated with Laser Therapy: A Systematic Review with Meta-Analysis|volume=26|issue=7|pages=537–544|journal=American Journal of Perinatology|publisher=Thieme Medical Publishers|doi=10.1055/s-0029-1215430|year=2009|pmid=19283655|s2cid=5913636 }}</ref>