The amniotic wrinkle: a pitfall in evaluating amniotic fluid for twins

Area of Science:

• Perinatology
• Fetal Medicine
• Diagnostic Ultrasound

Background:

• Assessing amniotic fluid volume in twin pregnancies is crucial for fetal well-being.
• Oligohydramnios in one twin presents diagnostic challenges during ultrasound.
• The intertwin membrane can create complex sonographic appearances.

Purpose of the Study:

• To describe a sonographic pitfall, the "amniotic wrinkle," in twin pregnancies.
• To identify image patterns that may lead to misinterpretation of amniotic fluid levels.
• To improve the accuracy of ultrasound assessment in complicated twin gestations.

Main Methods:

• Analysis of sonograms from twin pregnancies with initial assessments of adequate fluid.
• Identification of specific image patterns related to the intertwin membrane.
• Retrospective review of cases where one twin had oligohydramnios.

Main Results:

• The "amniotic wrinkle" is a fold in the intertwin membrane, appearing as a linear structure.
• This wrinkle can erroneously suggest adequate fluid when one twin has oligohydramnios or anhydramnios.
• Variations include fetal parts apposing within the fold or an "intrauterine sling" appearance.

Conclusions:

• Careful visualization of the intertwin membrane is essential in all fluid assessments.
• Utilizing images perpendicular to the initial view can help detect amniotic wrinkles.
• Accurate assessment of amniotic fluid in twins prevents misdiagnosis and ensures appropriate management.