Right iliac fossa pain in a pregnant woman
A 26-year-old woman at 24 weeks' gestation presents with 18 hours of periumbilical pain that has migrated to the right lower abdomen, anorexia and one episode of vomiting. Temperature is 37.9°C, pulse 104/min, blood pressure 112/70 mmHg. The uterus is consistent with 24 weeks and the fetal heart rate is 150/min. On examination there is tenderness in the right lower quadrant, maximal slightly above and lateral to the usual McBurney point, with guarding and rebound. White cell count is 15.8 × 10⁹/L with neutrophilia; urinalysis shows trace leukocytes only. Obstetric review confirms a viable pregnancy with no contractions and a closed cervix. Ultrasound of the appendix is inconclusive because the gravid uterus obscures the view.
1. How does pregnancy alter the presentation and interpretation of appendicitis, and what is the most appropriate next step in management?
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As the uterus enlarges, the appendix is displaced superiorly and laterally, so pain and tenderness shift away from McBurney point toward the right flank or upper quadrant. This displacement, together with stretching of the abdominal wall, reduces the reliability of classic signs and can mask guarding, which contributes to diagnostic delay. Physiological changes also confound interpretation: pregnancy causes a mild leukocytosis, so a white cell count of 15.8 × 10⁹/L is supportive but not decisive, and the neutrophil predominance plus anorexia and migration of pain remain meaningful. Nausea and vomiting are common in pregnancy and should not be dismissed as normal when accompanied by focal tenderness. The trace leukocytes on urinalysis make urinary tract infection less likely but do not exclude it. Given the inconclusive ultrasound, the next step is further imaging, preferably MRI without contrast, or CT if MRI is unavailable, because both have high sensitivity and CT radiation can be justified when needed. If imaging remains equivocal and clinical suspicion is high, diagnostic laparoscopy is appropriate; delay increases the risk of perforation, which carries substantial fetal loss and maternal morbidity. Involve obstetrics, give prophylactic antibiotics, and avoid unnecessary delay for repeat imaging.
2. If appendicectomy is confirmed as necessary, what perioperative considerations apply at 24 weeks?
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Proceed with laparoscopic appendicectomy where expertise exists; laparoscopy in the second trimester is generally safe and offers better visualisation, though open surgery is acceptable if adhesions or technical limits arise. Place the patient in a left lateral tilt to reduce aortocaval compression, maintain maternal oxygenation and blood pressure, and involve obstetric and neonatal teams. Give appropriate antibiotics that are safe in pregnancy, ensure thromboprophylaxis, and use fetal monitoring where gestation permits. Avoid unnecessary delay: perforated appendicitis markedly increases fetal loss and preterm labour. Postoperatively, monitor for contractions and provide tocolysis only if clinically indicated rather than routinely.