Pregnancies complicated by severe polyhydramnios are associated with a high rate of underlying fetal anomaly. Amnioreduction may be offered to alleviate maternal symptoms. This is a retrospective study of amnioreductions performed on singleton and twin gestations complicated by symptomatic polyhydramnios between 2010 and 2023 at our tertiary referral center. The indications, procedural techniques and pregnancy and neonatal outcomes were retrieved from an archive database and reviewed with the use of the maternal and child medical record chart, the hospital electronic clinical discharge report and telephone recalls. Our study comprised 86 pregnancies, 65 singletons and 21 twin pregnancies. Fetal anomalies were identified in 79% of cases, mainly gastrointestinal obstructive anomalies; 9.3% of cases were idiopathic. The median gestational age at first amnioreduction was 32.5 weeks, and peri-procedural complications were rare (1 case of placental abruption and 2 cases of preterm delivery). The median gestational age at delivery was 36.5 weeks, with a median prolongation of the pregnancy from the time of first drain until birth of 30 days. Preterm labor < 37 weeks occurred in 48.8% of procedures, with 26.7% of patients delivering before 34 weeks and pPROM < 36 weeks recorded in 23.2% of cases. In conclusion, amnioreduction offered to alleviate maternal symptoms is a reasonably safe procedure with a low complication rate. These pregnancies necessitate management in a tertiary referral center because of their need for a multidisciplinary approach both prenatally and postnatally.

Background and Clinical Significance: Ultrasonographic diagnosis of twin pregnancies has become routine, with chorionicity playing a crucial role in assessing associated risks. Traditionally, monochorionic (MC) twins were believed to derive from a single zygote, ensuring sex concordance. However, recent cases of dizygotic monochorionic (MCDZ) twins challenge this paradigm. In this paper, four cases of MCDZ twins with sex discordance are described. Case presentation: Case 1 and case 2 describe two spontaneous MC/diamniotic twin pregnancies in which sex discordance between twins was attributed to blood chimerism. Case 3 is about a MC/diamniotic twin pregnancy derived from a single blastocyst transfer after in vitro fertilization (IVF), and that was complicated by twin-to-twin transfusion syndrome, with zygosity testing confirming the dizygosity. Case 4 is a twin anemia polycythemia sequence diagnosed after birth in twins considered dichorionic during pregnancy (due to sex difference) and defined as monochorionic after placental examination. Conclusions: The prevalence of monochorionic dizygotic (MCDZ) twins remains uncertain, and many cases likely go unnoticed, particularly when twins are of the same sex. In twin pregnancies, determining chorionicity during the first-trimester ultrasound (US) is critical. Accurate identification of monochorionicity is essential for managing potential complications. Careful verification of sex concordance between twins is necessary. In cases of sex discordance, amniocentesis is required for karyotype evaluation and zygosity testing.