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

Ultrasound image of lambda sign in first trimester

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


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


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


USG First TrimesterIndicates
1T signMonochorionicity
2Lambda (λ) signDichorionicity
Lambda (λ) sign


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