The following are multiple choice questions (with answers) about medical knowledge.   To determine the ability of early sonogram to predict the presentation of twin A at birth. A retrospective cohort study was conducted on all twin pregnancies evaluated at our Fetal Evaluation Unit from 2007 to 2009. Sonogram records were reviewed for the presentation of twin A at seven gestational age intervals and inpatient medical records were reviewed for the presentation of twin A at delivery. The positive predictive value, sensitivity, and specificity of presentation as determined by ultrasound, at each gestational age interval, for the same presentation at delivery were calculated. Two hundred and thirty-eight twin pregnancies met inclusion criteria. A total of 896 ultrasounds were reviewed. The positive predictive value of cephalic presentation of twin A as determined by ultrasound for the persistence of cephalic presentation at delivery reached 95% after 28 weeks gestation. The positive predictive value for noncephalic presentation as established by sonogram for noncephalic at delivery was>90% after 32 weeks gestation.   **Question:** Can third trimester ultrasound predict the presentation of the first twin at delivery?   (A) Yes   (B) No   (C) Maybe
['(A) Yes <> answer', 'The following are multiple choice questions (with answers) about medical knowledge. <> instruction', '(A) Yes \n (B) No \n (C) Maybe <> possible answers', 'To determine the ability of early sonogram to predict the presentation of twin A at birth. A retrospective cohort study was conducted on all twin pregnancies evaluated at our Fetal Evaluation Unit from 2007 to 2009. Sonogram records were reviewed for the presentation of twin A at seven gestational age intervals and inpatient medical records were reviewed for the presentation of twin A at delivery. The positive predictive value, sensitivity, and specificity of presentation as determined by ultrasound, at each gestational age interval, for the same presentation at delivery were calculated. Two hundred and thirty-eight twin pregnancies met inclusion criteria. A total of 896 ultrasounds were reviewed. The positive predictive value of cephalic presentation of twin A as determined by ultrasound for the persistence of cephalic presentation at delivery reached 95% after 28 weeks gestation. The positive predictive value for noncephalic presentation as established by sonogram for noncephalic at delivery was>90% after 32 weeks gestation. \n   Can third trimester ultrasound predict the presentation of the first twin at delivery? <> context@']