Rectus sheath hematoma (RSH) is a rare, but important potential cause of acute upper abdominal pain in pregnancy. We report a patient with history of hemolysis, elevated liver enzymes, low platelets syndrome who presented with upper abdominal pain, hypotension, elevated hepatic transaminase levels, and a visibly enlarging right costal margin mass at 33 weeks' gestation. She underwent emergent cesarean delivery and upper abdominal exploration with findings of a large hematoma involving the entire right rectus sheath. The current case illustrates that the diagnosis of an RSH in pregnancy can be difficult as its presentation can mimic many common causes of abdominal pain seen outside of pregnancy, as well as many specific to pregnancy. Review of the published cases from the past 20 years shows that correct diagnosis remains difficult in pregnancy despite advances in diagnostic imaging. Although management of an RSH outside of pregnancy is frequently conservative, it is very often treated surgically in pregnant patients and often leads to preterm delivery.