Difficult diagnosis in the emergency department: hyperemesis in early trimester pregnancy because of incarcerated maternal diaphragmatic hernia.

Hyperemesis gravidarum is a frequent presentation to the ED, which usually resolves with fluid rehydration and antiemetics. Early incarcerated maternal diaphragmatic hernia might be misdiagnosed as relatively benign hyperemesis gravidarum in the first two trimesters of pregnancy. Diagnosis is missed because of non-specific presentation with abdominal pain, nausea and vomiting. Hernias rarely become symptomatic even in latter stages of pregnancy, as the uterus increases in size with each trimester and with raised intra-abdominal pressure from uterine contraction during labour. Symptoms progress with incarceration and strangulation of abdominal contents within the thoracic cavity, compression of the lung and disruption of caval venous return. A woman at 19-week gestation presented with delayed diagnosis of strangulated diaphragmatic hernia, representing the earliest gestation in the published literature when this has occurred. She had repeatedly been misdiagnosed with hyperemesis gravidarum. It is worthwhile considering incarcerated maternal diaphragmatic hernia as an unusual cause of refractory vomiting in pregnancy, when associated with clinically significant upper abdominal pain and progressive respiratory embarrassment. This might occur as early as the mid-second trimester, and without uterine contraction.