Abstract: After mid- trimester loss（MTL） between 12 and 24 weeks gestation, cervical incompetence is found to be common cause. In a subsequent pregnancy when transvaginal cerclage has failed, the recent recommendation is to consider transabdominal cerclage（TAC） insertion with 90% success rate. This chapter highlights the experience of over 20 years use of TAC in a single centre. Preconceptual TAC insertion is compared to first trimester use while the presence of other pathology increases the preterm delivery rate. In summary, preconceptual TAC（PC TAC） is more successful in preventing repeat spontaneous mid-trimester loss and preterm labour and is associated with less surgical and pregnancy-related morbidity compared to first trimester TAC insertion（T1 TAC）. Women with MTL represent a heterogeneous group, with widely varying presentations and aetiology. The true incidence of this pregnancy complication is difficult to ascertain as no accurate data collection has been published. In Liverpool UK, a standardised protocol with baseline prepregnancy investigations has been universally employed since the late 1980′s. Causative factors include anti-phospholipid syndrome, cervical incompetence, infection and congenital uterine anomaly. Following screening of 504 consecutive cases of MTL, we have found one potential cause in 50%, dual causes in 10% and triple causes in 1%.