Perinatal outcome, placental pathology, and severity of discordance in monochorionic and dichorionic twins

Abstract

Severe discordance is more frequent and has greater morbidity in monochorionic than dichorionic twins. The most frequent findings in the placentas of severely discordant twins were small placental weight and umbilical cord abnormalities.

Increased Prevalence of Fetal Thrombi in Monochorionic-Twin Placentas

“…Fetal thrombosis was associated with SGA, confirming the work of others. 6,7 Redline et al 8 reported that avascular villi with occlusion of fetal vessels in the placenta was associated with intrauterine growth retardation and discordant growth in monochorionic-twin placentas. Fetal vessel thrombosis is common in the placentas of SGA infants.…”

“…Victoria et al 6 and Hanley et al 7 reported that severe discordance occurred significantly more often in monochorionic than in dichorionic twins and was significantly associated with velamentous cord insertions. Redline et al 8 demonstrated that peripheral insertion of the umbilical cord and avascular villi were associated with abnormal growth in twins.…”

Mean Arterial Pressure in Extremely Low Birth Weight Concordant and Discordant Twins During the First Day of Life

“…Discordancy was calculated using the intertwin birth weight difference expressed as a percentage of the larger twin's birth weight. 2,3,16,17 Discordancy equal to or greater than 20% separates concordant from discordant twins. Zygosity was determined prenatally by ultrasound and postnatally by placental examination.…”

“…18 TTTX was diagnosed in identical twins by discordance in fetal weight and ultrasonographic documentation of polyhydramnios in one and olygohydramnios in the other. 2,17,19 Significant differences in umbilical cord hemoglobin, which are indicative of acute but not of chronic TTTX, were not used as diagnostic criteria. 2 All ELBW infants were treated empirically with ampicillin (100 mg/kg per day IV given in two doses every 12 hours) and gentamicin (5 mg/kg/day IV given every 48 hours) for 2 days if blood cultures were negative.…”

“…Severe discordant twins without TTTX syndrome occurred in about 7% of dichorionic and about 20% of monochorionic pregnancies. 17 The most common etiology for this type of discordancy included different genetic potential, unequal sharing of placental mass, and placental insufficiency. 19,32,33 Large discordant infants are usually appropriate for gestation whereas small discordant twins are intrauterine growth restricted.…”