Chronic abruption-oligohydramnios sequence (CAOS) has been described to include the following criteria: (1) clinically significant vaginal bleeding in the absence of placenta praevia or other identifiable source of bleeding, (2) amniotic fluid volume initially documented as normal, and (3) oligohydramnios eventually developing without concurrent evidence of ruptured membranes. It is clinically significant as patients with CAOS are at a high risk for both poor perinatal and neonatal outcomes, more notably increased incidence of small-for-gestational age (SGA) neonates and neonatal chronic lung disease (CLD).
We report a case of CAOS in a 19 year old mother in conjunction with a history of substance abuse, including crystal methamphetamine, alcohol and tobacco. Ultrasound findings of oligohydramnios, a grossly enlarged placenta and a small for gestational age foetus (SGA) were first seen on an emergency ultrasound for lower abdominal pain at 17 weeks. She represented at 21 weeks with further abdominal pain and light vaginal bleeding, where a repeat ultrasound confirmed oligohydramnios and a large placenta with significant retro placental bleeding and a severely growth restricted foetus. A spontaneous vaginal delivery of a stillborn female followed approximately two days later. The karyotype was normal and the autopsy revealed organ weights less than expected, particularly the lungs with the left and right lung weighing 1.73 and 2.33 grams respectively (expected weights 5.09±1.26g and 5.95±1.57g respectively). Also noted was an extensive acute on chronic marginal, parenchymal and retroplacental haemorrhage.
After a comprehensive review of the literature, this is believed to be the first published case of CAOS in a patient with poly-substance abuse, including intravenous crystal methamphetamine. In addition to comparing the imaging findings with associated histopathology from this case, this article seeks to review the current literature surrounding CAOS, detailing the natural history, imaging findings, treatment and potential impact on future pregnancies.
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