WBR0333: Difference between revisions
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<br> > 13 days: Monochorionic monoamniotic conjoined twin pregnancy | <br> > 13 days: Monochorionic monoamniotic conjoined twin pregnancy | ||
|EducationalObjectives= | |||
Monochorionic diamniotic twin pregnancy occurs when the fertilized egg cleaves at 4-8 days post-fertilization. | Monochorionic diamniotic twin pregnancy occurs when the fertilized egg cleaves at 4-8 days post-fertilization. | ||
|AnswerA=Dichorionic diamniotic twin pregnancy | |AnswerA=Dichorionic diamniotic twin pregnancy | ||
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|AnswerEExp=Monochorionic monoamniotic conjoined twin pregnancy occurs when cleavage takes place > 13 days post-fertilization. If no cleavage occurs whatsoever, no twinning will take place. | |AnswerEExp=Monochorionic monoamniotic conjoined twin pregnancy occurs when cleavage takes place > 13 days post-fertilization. If no cleavage occurs whatsoever, no twinning will take place. | ||
|RightAnswer=B | |RightAnswer=B | ||
|WBRKeyword=monochorionic, dichorionic, monoamniotic, diamniotic | |WBRKeyword=monochorionic, dichorionic, monoamniotic, diamniotic, pregnancy, conjoined twins, fertilization, cleavage, fertilized, post-fertilization, post, zygote, monozygote, monozygotic | ||
|Approved=No | |Approved=No | ||
}} | }} |
Revision as of 16:15, 14 July 2014
Author | [[PageAuthor::Rim Halaby, M.D. [1]]] |
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Exam Type | ExamType::USMLE Step 1 |
Main Category | MainCategory::Physiology |
Sub Category | SubCategory::Reproductive |
Prompt | [[Prompt::A 28 year old pregnant woman presents to her gynecologist's office for a routine pregnancy visit. In the office, the gynecologist performs a pregnancy ultrasound. He informs the patient that she has twins. Then he explains to the patient that most probably the cleavage of the fertilized egg occurred between day 4 and day 8 post-fertilization. Which of the following findings on ultrasound is most likely present in this patient?]] |
Answer A | AnswerA::Dichorionic diamniotic twin pregnancy |
Answer A Explanation | AnswerAExp::Dichorionic diamniotic twin pregnancy occurs when cleavage takes place between 0-4 days post-fertilization. |
Answer B | AnswerB::Monochorionic diamniotic twin pregnancy |
Answer B Explanation | AnswerBExp::Monochorionic diamniotic twin pregnancy occurs when cleavage takes place between 4-8 days post-fertilization. |
Answer C | AnswerC::Dichorionic monoamniotic twin pregnancy |
Answer C Explanation | AnswerCExp::Dichorionic monoamniotic twin pregnancy is not possible. |
Answer D | AnswerD::Monochorionic monoamniotic twin pregnancy |
Answer D Explanation | AnswerDExp::Monochorionic monoamniotic twin pregnancy occurs when cleavage takes place between 8-12 days post-fertilization |
Answer E | AnswerE::Monochorionic monoamniotic conjoined twin pregnancy |
Answer E Explanation | [[AnswerEExp::Monochorionic monoamniotic conjoined twin pregnancy occurs when cleavage takes place > 13 days post-fertilization. If no cleavage occurs whatsoever, no twinning will take place.]] |
Right Answer | RightAnswer::B |
Explanation | [[Explanation::While dizygotic twins always form from 2 separately fertilized eggs, monozygotic twins form from 1 fertilized egg that later splits into 2 zygotes very early during pregnancy. The time post-fertilization by which the fertilized egg cleaves is very important for determining the number of chorions and amnions.
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Approved | Approved::No |
Keyword | WBRKeyword::monochorionic, WBRKeyword::dichorionic, WBRKeyword::monoamniotic, WBRKeyword::diamniotic, WBRKeyword::pregnancy, WBRKeyword::conjoined twins, WBRKeyword::fertilization, WBRKeyword::cleavage, WBRKeyword::fertilized, WBRKeyword::post-fertilization, WBRKeyword::post, WBRKeyword::zygote, WBRKeyword::monozygote, WBRKeyword::monozygotic |
Linked Question | Linked:: |
Order in Linked Questions | LinkedOrder:: |