Spontaneous resolution of prenatally detected dural sinus thrombosis: Case series and review of the literature 1 Hoetschl, J., 1, 2 Bamfo, J. E. A. K., 1 Tingi, E., 1,2 Bullen, P. J., 3Thorne, J., 4 Whitby, E. H. 1 Department of Obstetrics and Gynaecology, 2Fetal Medicine Unit at St Mary’s Hospital, Manchester UK. 3 Department of Paediatric Neurology, Royal Manchester Children’s Hospital, Manchester UK,. 4Academic unit of Reproductive and developmental medicine, Jessop Wing, University of Sheffield, Sheffield, UK. Dural sinus thrombosis (DST) is a rare fetal cerebral abnormality. We present six cases of (DST), four of which spontaneously resolved with good long term neonatal outcome. Two patients chose to terminate their pregnancies. In all cases, MRI captured the spontaneous resolution. Case 1 Case 2 Case 3 Case 4 Case 5 Case 6 US; 20 weeks,30x 15mm posterior fossa cyst, 23x 7mm temporal cystic lesion US; 21 weeks, 29x17x23 mm posterior fossa cyst, displaced cerebellum, ventriculomegaly US; 27 weeks, 27 x21x13mm partially calcified cyst, supra-tentorial DST US; 20 weeks, Posterior fossa cyst US 21 weeks; Posterior fossa cyst, no Doppler flow and no obvious brain abnormality US; 20 weeks, bilateral mild ventriculomegaly cystic lesion in the occipital region of the brain MRI; DST displacing the cerebellum, rest of brain normal TORCH negative No clotting abnormality MRI; 22 and 34 weeks: Dural sinus fistula reducing to 2x2x2mm ventricles normal MRI: Reduction in size and no deleterious effect on venous drainage MRI; 40x30x30 mm cyst, central clot, displaced cerebellum/occipital lobes. MRI;27 and 37 weeks; cyst increased (50x40x 30 mm), clot decreased MRI; 23 weeks,30x 30x30mm lesion, continuous with sagittal and transverse sinuses, displacing occipital horns MRI; 21+2 weeks; mild bilateral ventriculomegaly Posterior fossa lesion with clot, displaced cerebellum and occipital lobes, comm- unicating with sagittal/ transverse/ sigmoid sinuses Postnatal MRI; First week, clot in inferior part of sagittal sinus and Torcula, resolving Postnatal MRI; Spontaneous resolution Postnatal MRII; At 6 months; Partial thrombus in the dural sinus fistula Torcula Postnatal MRI; At 3 , 6 and 36 months, small DST, resolving Intact Neurology at 5 months old Intact Neurology at 3 years old Intact neurology at 12 months old Intact neurology at 36 months old TOP; Post-mortem: no clot TOP, declined post-mortem Differential diagnosis such as maternal thrombophilia, clotting disorders, infection, tumors, haemorrhage and vein of Galen aneurysm should also be excluded.Counselling remains challenging due to the small numbers of cases with long term follow up and parents terminating the pregnancy because of uncertainty. Previous series have reported good neurodevelopmental outcomes of 63 and 70%, consistent with our finding. In conclusion, from our case series and review of the literature, spontaneous resolution or regression of DST in the antenatal period may suggest a good long term neonatal prognosis. Where the thrombus remains extensive, prognosis should be guarded. Prenatal MRI is an important adjunct to ultrasound in the diagnosis and management of venous sinus thrombosis. References: Prenat Diagn 2009; 29: 808–813. Eur Radiol (2008) 18: 692–699, Ultrasound Obstet Gynecol 2008; 32: 188–198, Pediatr Radiol (2012) 42:536–543 Thrombosis of the fetal dural sinuses is rare. DST typically occurs in the context of Dural sinus malformation (DSM), a congenital abnormality characterised by dilated or cystic dural venous sinus’ with associated arteriovenous shunt. Prenatal ultrasound demonstrates a round sonolucent area or echogenic mass in the posterior fossa, with possible mass effect. MRI often describes a mass at the torcular herophili with or without extension into the superior sagittal sinus, with or without mass effect or dilation of the cerebral ventricles. The brain architecture is typically normal. There have been 53 cases published in the literature as far as we are aware. In 14 (26%), the women opted for termination of pregnancy and in 39 (74%), continued the pregnancy. One child with aneuploidy suffered from seizures. In 29/38 (76%) cases, there was normal neurodevelopment up to 6 yrs follow up. In the presence of partial or complete resolution, 25/28 (89%) of children had intact long term neurodevelopment, 2/28 (7%) neurodevelopmental delay and one cases (4%) suffered neonatal death. Where the DST remained the same size, intact neurodevelopment occurred in 2/5 (40%) cases, with 3/5(60%) suffering developmental delay or neonatal death. The majority of cases that demonstrated an increase in the DST resulted in termination of pregnancy (3/4) and neonatal death (1/4).