Guideline for Evaluation and Management of Acute Abdominal Pain in Late Pregnancy

Immediate Clinical Assessment

Guarding, rebound tenderness, or rigidity (peritoneal signs) in a pregnant patient indicate a surgical emergency that requires immediate laparotomy. 1
Tachycardia in pregnancy is a strong predictor of serious maternal complications and should prompt urgent evaluation. 2

A platelet count < 150 × 10⁹/L supports a diagnosis of HELLP syndrome, which occurs in 0.2–0.6 % of pregnancies. 3
AST/ALT > 300–1,000 U/L, low antithrombin III, elevated PT, and low fibrinogen are characteristic of acute fatty liver of pregnancy (incidence 0.005–0.010 %). 3
Total bile acids > 10 µmol/L (or AST/ALT 2–30 × ULN) suggest intra‑hepatic cholestasis of pregnancy. 3

HELLP syndrome: abdominal pain, nausea/vomiting, often with pre‑eclampsia; immediate delivery is required once diagnosed. 3
Acute fatty liver of pregnancy: abdominal pain, nausea/vomiting, jaundice, hypoglycemia; immediate delivery is required once diagnosed. 3
Intra‑hepatic cholestasis of pregnancy: may present with pruritus and abnormal liver enzymes; evaluate total bile acids. 3

Appendicitis is the most common cause of abdominal pain requiring emergency surgery in pregnancy; the appendix may be displaced by the gravid uterus. 5
Bowel obstruction or volvulus should be suspected when pain is severe and disproportionate to physical findings. 1
Cholecystitis risk is increased in pregnancy; ultrasound findings include gallbladder wall thickening > 3 mm and pericholecystic fluid. 5

Viral gastroenteritis is usually self‑limited, presenting with a single episode of vomiting and loose stools without labor. 4

Ultrasound is the first‑line imaging modality for any pregnant patient with abdominal pain. 2
Obstetric ultrasound evaluates fetal well‑being, amniotic fluid volume, and placental position. 2
Abdominal ultrasound assesses the gallbladder, appendix (if visualized), and kidneys for hydronephrosis. 5
When ultrasound is inconclusive and surgical pathology is suspected, MRI without contrast provides ≈ 97 % sensitivity and ≈ 95 % specificity for appendicitis in pregnancy. 2
CT with IV contrast should be reserved for life‑threatening situations where ultrasound and MRI are nondiagnostic; a single‑acquisition CT delivers < 25 mGy fetal exposure, which carries minimal risk. 2

Obtain immediate surgical consultation. 2
Initiate broad‑spectrum antibiotics as part of acute abdomen management. 1
Proceed to prompt laparotomy for overt peritonitis. 1
Employ a multidisciplinary team (acute‑care surgeon, obstetrician, anesthesiologist). 1

Administer IV isotonic saline to correct volume depletion. 6
Use metoclopramide or ondansetron for nausea/vomiting; metoclopramide is associated with less drowsiness. 4
Correct electrolyte abnormalities as needed. 4
Give thiamine 100 mg daily if vomiting is prolonged to prevent Wernicke encephalopathy. 3
Perform serial abdominal examinations every 4–6 hours to monitor for evolving peritoneal signs. 6
Monitor vital signs closely, especially for tachycardia. 6

Admit for observation if any of the following are present: inability to tolerate oral intake, persistent vomiting, pain requiring IV analgesia, or laboratory abnormalities suggestive of HELLP/AFLP. 5
Discharge with 24–48 hour follow‑up when the patient tolerates oral intake, pain is controlled with oral analgesics, vital signs are stable, no peritoneal signs are present, and liver chemistry is normal. 5

Do not attribute all abdominal pain to normal pregnancy changes without first excluding serious pathology. 2
Do not delay surgical intervention for confirmed appendicitis; maternal and fetal outcomes worsen with postponement. 2
Do not withhold CT imaging in life‑threatening scenarios; the fetal radiation dose from a single‑acquisition CT is low (< 25 mGy). 2
Persistent abnormal liver enzymes after symptom resolution should trigger further investigation beyond simple gastroenteritis. 3