An acute abdomen is a potentially serious acute condition of the abdomen which is usually associated with sudden onset of abdominal pain. An acute abdomen whether during or outside pregnancy is potentially serious and often requires emergency surgery.

During pregnancy, there are additional pregnancy-related conditions that could lead to an acute abdomen, and some are potentially more serious than others.

An acute abdomen can be categorized into categories that can happen at any time or those that are related exclusively to pregnancy.

Conditions that cause acute abdomen and which are associated with pregnancy:

• Acute pyelonephritis
• Acute cystitis
• Acute cholecystitis
• Acute fatty liver of pregnancy
• Rupture of rectus abdominis muscle
• Torsion of the pregnant uterus

Conditions that cause acute abdomen and which are due to pregnancy:

• Ruptured ectopic pregnancy
• Septic abortion with or without peritonitis
• Acute urinary retention due to retroverted gravid uterus
• Conditions resulting from pregnancy that cause acute abdomen in later pregnancy include the following:
• Red degeneration of myoma
• Torsion of pedunculated myoma
• Placental abruption
• Placenta percreta
• HELLP (hemolysis, elevated liver function, and low platelets) syndrome – Spontaneous rupture of the liver
• Uterine rupture
• Chorioamnionitis

Gastrointestinal causes of acute abdomen:

• Acute appendicitis
• Acute pancreatitis
• Peptic ulcer
• Gastroenteritis
• Hepatitis
• Bowel obstruction or perforation
• Herniation
• Meckel diverticulitis
• Toxic megacolon
• Pancreatic pseudocyst

Genitourinary causes of acute abdomen:

• Ovarian cyst rupture
• Adnexal torsion
• Ureteral calculus
• Rupture of renal pelvis
• Ureteral obstruction

Vascular causes of acute abdomen:

• Superior mesenteric artery syndrome
• Thrombosis/infarction - Specifically, mesenteric venous thrombosis
• Ruptured visceral artery aneurysm
• Splenic artery aneurysm

Respiratory causes of acute abdomen:

• Pneumonia
• Pulmonary embolism

Additional causes of acute abdomen:

• Intraperitoneal hemorrhage
• Splenic rupture
• Abdominal trauma
• Acute intermittent porphyria
• Diabetic ketoacidosis
• Sickle cell disease