This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Gynaecology & Obstetrics
[{'content': 'True about vaccum extraction of fetus :\n(A)Can be used in non dilated cervix\n(B)Can be used in incompletely dilated cervix\n(C)Used in Face presentation\n(D)Applied 3cm post, to Anterior fontanel\n(E)Applied 3cm ant. to posterior fontanel \nSelect and explain. \nA. AB, B. BE, C. CA, D. DB', 'role': 'user'}, {'content': "Answer: B \nExplanation: The centre of the cup should be over the sagittal suture and about 3 cm in front of the posterior fontanel toward the face.\n\nAnterior placement on the fetal cranium-near the anterior fontanel rather than over the occiput-will result in cervical spine extension unless the fetus is small'-\nWilliam's Obstetrics 23rd/523 Ventouse Extraction: Indications As an alternative to forceps operation\nAs an alternative to rotational forceps as in occipital transverse or posterior position \xa0Delay in the descent of the head in case of the second baby of twins.\nDelay in the late first stage of labour (uterine inertia). Conditions To Be Fulfilled\nThere should not be slightest bony resistance below the head.\nThe head of a singleton baby should be engaged.\nCervix should be at least 6 cm dilated (preferably only cervical rim may be left behind).\n\nContraindications:\n\nAny presentation other than vertex (face, brow, breech)\nPreterm fetus (<34 weeks). Chance of scalp avulsion or sub-aponeurotic haemorrhage.\nSuspected fetal coagulation disorder.\nSuspected fetal macrosomia", 'role': 'assistant'}]