Shape of nulliparous cervical canal is :

Transverse [Ref: BDC 4/e, Vol 2, p 359; Gray's Anatomy 38/e, p 1871; Jeffcoate's Gynaecology 6/e, p 31 Don't get confused with the answer . Question is about cervical canal & not the external os. The external os is circular in a nulliparous woman & transverse or slit like in parous women. In a nulliparous women, the cervical canal is spindle shaped or fusiform longitudinally, flattened transversely and broadest at mid level. The canal has an anterior & a posterior wall. These walls have mucosal folds resembling branches of a tree so are known as arbor vitae uteri. These folds are lost after child bih giving a conical shape to the cervical canal. So, Nulliparous External os Circular Cervical canal Fusiform longitudinally & transverse horizontally Multiparous Transverse/slit like Conical