Lambda (λ) sign in USG

Lambda (λ) sign

What is lambda sign?

• Lambda sign refers to the triangular projection of chorion between the layers of inter-twin membranes which resembles the Greek alphabet “lambda”.

What is suggested by Lambda (λ) sign in USG?

• Lambda (λ) sign in USG – Strongly suggests a dichorionic twin pregnancy.

Lambda (λ) sign in USG is best seen in which Trimester?

• Best seen in the first trimester – between 10-14 weeks

What is the othername for Lambda (λ) sign in USG?

• Twin peak sign is other name for lambda (λ) sign
• Lambda (λ) sign is a useful indicator of dichorionicity

ResearchGate. Available from: https://www.researchgate.net/figure/Ultrasound-image-of-lambda-sign-in-first-trimester_fig1_271632101 [accessed 12 Jan, 2023]

Lambda (λ) sign in USG

http://www.fetalultrasound.com/online/text/11-073_files/image018.jpg

Lambda (λ) sign in USG

Transabdominal pelvic ultrasound image obtained at 16 weeks of gestation shows both foeti labeled A and B. The limbs of the lambda sign are highlighted with arrows. The ‘peak’ is labeled with an asterisk

Source : https://media.springernature.com/full/springer-static/image/art%3A10.1007%2Fs00261-017-1356-4/MediaObjects/261_2017_1356_Fig2_HTML.jpg?as=webp

Transabdominal pelvic ultrasound image obtained at 16 weeks of gestation shows both foeti labeled A and B. The limbs of the lambda sign are highlighted with arrows. The ‘peak’ is labeled with an asterisk

@IJGOLive on Twitter

“‘Chorionicity is determined by membrane thickness at the site of insertion into the placenta; a T sign indicates monochorionicity & a lambda (λ) sign is diagnostic of dichorionicity’ – FIGO’s Good Clinical Practice Advice on Management of Twin Pregnancy https://t.co/gZHaeU1T67”