Midtrimester isolated oligohydramnios in monochorionic diamniotic multiple gestations

J Matern Fetal Neonatal Med. 2019 Feb;32(4):590-596. doi: 10.1080/14767058.2017.1387530. Epub 2017 Oct 12.


Objective: To describe the natural history and perinatal outcomes of monochorionic diamniotic twins with midtrimester isolated oligohydramnios (iOligo).

Materials and methods: We performed a retrospective study of iOligo patients who were initially referred for the management of evolving twin-twin transfusion syndrome (TTTS) or selective intrauterine growth restriction (sIUGR). iOligo was defined as a maximum vertical pocket of amniotic fluid of ≤2 cm in the iOligo twin's sac and normal fluid level (>2 and <8 cm) in the co-twin's sac. "Group A" patients did not subsequently develop TTTS or sIUGR Type II (umbilical artery persistent absent or reversed end-diastolic flow), and "Group B" patients did develop TTTS or sIUGR Type II. Results are reported as median (range).

Results: Of the 828 patients with complicated monochorionic twin gestations referred for possible TTTS or sIUGR, 36 (4.3%) were initially diagnosed with iOligo. After initial consultation, two patients terminated and one was lost to follow-up, resulting in a final study population of 33. Group A had 10 patients (30.3%) and Group B had 23 patients (69.7%). In Group A, nine of the 10 were expectantly managed, resulting in a median gestational age (GA) at delivery of 34.7 (18.0-36.4) weeks, a 30-day perinatal survival of at-least-one twin of 88.9% (8/9), and dual 30-day survivors in 8/9 (88.9%). In Group B, 12 (52.2%) developed TTTS and 11 (47.8%) developed sIUGR Type II. Fifteen Group B patients had laser surgery, resulting in a median GA at delivery of 33.7 (26.4-37.1) weeks, a 30-day perinatal survival of at-least-one twin of 100% (15/15), and dual survivorship of 46.7% (7/15).

Conclusions: Our findings show that the majority of patients with midtrimester iOligo have fetal growth restriction of the affected twin and subsequently progress to TTTS or sIUGR Type II.

Keywords: Monochorionic twins; TTTS; discordant amniotic fluid; oligohydramnios; sIUGR.

MeSH terms

  • Female
  • Fetal Growth Retardation / etiology*
  • Fetal Growth Retardation / mortality
  • Fetofetal Transfusion / etiology*
  • Fetofetal Transfusion / mortality
  • Gestational Age
  • Humans
  • Infant, Newborn
  • Oligohydramnios / diagnosis
  • Oligohydramnios / mortality*
  • Pregnancy
  • Pregnancy Trimester, Second
  • Pregnancy, Twin*
  • Retrospective Studies
  • Twins, Monozygotic*