SECTION 3: HYPEREMESIS GRAVIDARUM

1. Definition

Nausea and vomiting in pregnancy, or morning sickness, are common. Seen in 88% of pregnancies, this usually resolves by week 16. Various etiologies have been proposed, including elevated levels of human chorionic gonadotropin, thyroid hormone, or the intrinsic hormones of the gut. There seems to be a disordered motility of the upper gastrointestinal tract that contributes to the problem. Despite the nausea and vomiting, patients are usually able to maintain adequate nutrition. However, patients will occasionally become dehydrated and potentially develop electrolyte abnormalities. When this occurs, the diagnosis of hyperemesis gravidarum is given. In particular, hyperemesis is common in the setting of molar pregnancies and a viable Intra uterine Pregnancy IUP should always be documented in patients with hyperemesis.

2. Treatment and Prognosis

For patients with true hyperemesis gravidarum, symptoms may persist into the third trimester and, rarely, until term. The goal of therapy is to maintain adequate nutrition. Upon presentation with dehydration, patients should be rehydrated and electrolyte abnormalities corrected. Since a hypochloremic alkalosis often results from extensive vomiting may respond to antiemetics. Compazine, Phenergan, Tigan, and Reglan are commonly used. If these fail, droperidol and Zofran can also be used safely in pregnancy. In the acute setting, antiemetics should be given intravenously, intramuscularly, or as suppositories because oral medications may be regurgitated prior to systemic absorption. In addition to antiemetics, ginger and supplementation with vitamin B12 have been utilized.

Long-term management of hyperemesis includes maintaining hydration, adequate nutrition, and symtomatic relief from the nausea and vomiting. Many patients respond to antiemetics and IV hydration. Once they are rehydrated, they will be able to use the antiemetic to control their nausea so that they are able to maintain oral intake. In addition, since hypoglycemia may contribute to the symptom of nausea, frequent small meals can help maintain more stable blood sugar and decrease nausea.

Rarely, patients will not respond to antiemetics and recurrent rehydration, but treatment with corticosteroids has been shown to decrease symptoms. Further, alternative treatment with acupuncture, acupressure, and nerve stimulation replicating such treatments has been demonstrated to decrease nausea as well. Even with these therapies, a small percentage of patients will require feeding tubes or even parenteral nutrition for the course of the pregnancy. As long as hydration and adequate nutrition are maintained, pregnancy outcomes are usually good.

（王皓）