This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Normal Labour, Subject name: Gynaecology & Obstetrics
Which of the following investigations are essential before cervical cerclage is performed? 
Select and explain. 
A. Estimate C-reactive protein levels, B. Perform a white cell count, C. Perform a transvaginal ultrasound scan to assess the cervical length and exclude funnelling, D. Perform an ultrasound scan for fetal abnormalities and screen for aneuploidy
D: Perform an ultrasound scan for fetal abnormalities and screen for aneuploidy
Answer: D: Perform an ultrasound scan for fetal abnormalities and screen for aneuploidy 
Explanation: Ans. is d, i.e. Perform an ultrasound scan for fetal abnormalities and screen for aneuploidy Before answering the question lets discuss a few details on cervical cerclage surgery.Nomenclature for cerclage applicationOld (1999)New (2007)Prophylactic, electiveHistory indicatedTherapeutic, salvageUltrasound indicatedRescue, emergency urgentPhysical examination indicatedRecommendations for history indicated cerclageShould be offered to women with 3 or more previous preterm births and/or second trimester lossesShould not be routinely offered to women with two or fewer previous preterm birth and/or second trimester losses (Level B evidence)Recommendations for USG indicated cerclageWomen with history of 1 or more spontaneous preterm births or/mid trimester losses with Y, V or U detected on USG or cervical length <25mm before 24 weeks-Not recommended for women without a history of spontaneous preterm delivery or second trimester losses with incidentally detected cervical length <=25mm-Not recommended for funneling of cervix in the absence of cervical shortening to <=25mm A cervical cerclage should be carried out in her as she has H/O 3 previous preterm deliveries.An ultrasound scan for fetal abnormalities and screening for aneuploidy should be carried out, before insertion of a history- indicated suture, to ensure both viability and the absence of lethal/major fetal abnormalities. Assessment of cervical length is not indicated before applying a history indicated cerclage. It is not essential to perform a white cell count or C-reactive protein levels before performing a cervical cerclage.