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247 Appendices NMH Annual Rep t | 2020 Cord coiling The cord normally has one coil per 5cm. Both hypo- and hypercoiled cords are associated with IUGR, fetal death, cord stricture, thrombosis and an abnormal response to labour. Abruption and retroplacental haemorrhage (RPH) RPH may be identified on pathologic examination of the placenta, but have been clinically silent. Conversely, dramatic clinical abruption may leave no changes in the placenta. In many cases RPH causes compression infarction of the placenta. Diffuse chorioamniotic haemosiderosis (DCH) This is diagnosed by the presence of haemosiderin- laden macrophages in the membranes and/or chorionic plate. Such placentas are more likely to show circumvallation, old peripheral blood clots and green discoloration. Clinically, DCH is associated with chronic vaginal bleeding, multiparity and smoking. Blood and breakdown products are released into the amniotic fluid. Oligohydramnios, IUGR and a lower gestational age at delivery have been found more commonly in cases with DCH. Persistent pulmonary hypertension and dry lung syndrome are more common in these neonates. DCH may represent chronic peripheral separation of the placenta, possibly from marginal venous bleeding (rather than the arterial bleed of abruption). ABNORMAL PLACENTAL DEVELOPMENT Delayed/abnormal villous maturation This is where the placenta has failed to develop appropriately for gestational age, partially or completely. It is a poorly understood entity, and is associated with diabetes. It is associated with an increased risk of stillbirth. Some cases may receive a descriptive diagnosis eg abnormal maturation or variable villous maturation where there is a mixed picture, with some areas showing delayed maturation and other areas accelerated maturation. The term "distal villous immaturity" is also used. Increased perivillous fibrin Localised increases in fibrin are common, but a diffuse increase, sometimes in a pattern called "maternal floor infarction" is associated with an adverse outcome. Placental weight In general, the term placenta weighs between one sixth and one seventh of the infant's weight, but a wide range of placental weights is seen in normal infants. The weight is given in the cases discussed where it is felt to be markedly abnormal. Fetoplacental weight ratio (median of around 7 at term) are sometimes used. Updated September 2018 Khong T Yee, Mooney EE, Ariel I et al. Sampling and definition of placental lesions. Amsterdam Placental Workshop Group Consensus Statement. Arch Pathol Lab Med 2016;140:698-713. Appendix 2: Classification of indications for caesarean section in spontaneous labour or after having had labour induced Fetal reason Caesarean section for fetal indication before any oxytocin has been given. Dystocia Inefficient uterine action/inability to treat/fetal intolerance Problem is inadequate progress with no fetal problems until oxytocin is started. Inefficient uterine action/inability to treat/ overcontracting Problem is inadequate progress but oxytocin does not reach maximum dose as per protocol in unit because of overcontracting uterus. Inefficient uterine action/poor response Problem is inadequate progress which does not improve after being treated with the maximum dose of oxytocin according to the protocol in the unit. Inefficient uterine action/no oxytocin Problem is inadequate progress which for whatever reason has not been treated with oxytocin. Efficient uterine action/CPD/POP* Adequate progress (1cm/hr) and in nulliparous women would need to have been treated with oxytocin) but vaginal delivery not possible. *In multiparous women the term CPD/POP is replaced with obstructed labour.