Context We present a challenging case of profound thrombocytopenia in pregnancy following initial presentation with severe hyperemesis gravidarum (HG). Investigations led to a working diagnosis of exclusion, idiopathic thrombocytopenia (ITP). Objective In this report, we describe the clinical presentation prior to the multi-disciplinary challenge of investigating severe thrombocytopenia. We evaluate current guidance on the diagnosis and management of ITP. We also hypothesize, nutritional deficiencies may play a crucial role in the development of profound thrombocytopenia at such an early phase in pregnancy. The risk of spontaneous haemorrhage in pregnancy with platelet counts less than 20 x109/L can be significant and is associated with inherent morbidity/ mortality to mother and child; the correct diagnosis and management is imperative. Method Retrospective case report Patient A 46-year old multiparous Eritrean lady presented at 7-weeks’ gestation with a 2-week history of severe HG. She also reported over 10% loss of body weight and epigastric pain. Intervention & results On admission, all electrolytes and blood counts were within normal ranges, with a platelet count of 150 x109/L. An ultrasound scan showed an intrauterine pregnancy and 8cm subchorionic haematoma which showed resolution on subsequent imaging. After an unsuccessful trial of several anti-emetic therapies, the addition of intravenous steroid therapy was successful. She then entered a prolonged period of refeeding syndrome, with a potassium nadir of 2.7 mEq/L. As her presenting symptoms resolved, her platelet count suddenly deteriorated from 140 to 15 x109/L. She was trialled on immunoglobulin therapy with no response and showed a very muted response to high dose steroids. Extensive investigations inclusive of bone-marrow biopsy, viral and auto-immune screen and assessment for Haemolytic Uraemic Syndrome/ Thrombotic Thrombocytopenic Purpura failed to identify establish an alternative diagnosis; a presumptive diagnosis of ITP was made. Discussion We describe a case of profound thrombocytopenia complicating first trimester pregnancy. We demonstrate the challenges in reaching a diagnosis which is made by exclusion but so far fails to adequately respond to standard ITP treatment. Although the result remains unsatisfactory, this case highlights the diverse aetiology of thrombocytopenia and the importance of a multidisciplinary approach with close monitoring of both mother and child.