Appendicitis in Pregnancy: Causes, Diagnosis, Imaging, and Management

on

 Introduction

Appendicitis remains the most common non-obstetric surgical emergency during pregnancy. Diagnosing and managing this condition requires a delicate balance between maternal health and fetal safety. In this expert column, we will explore the cause, etiology, pathophysiology, epidemiology, clinical presentation, imaging features, treatment, and prognosis of appendicitis in pregnancy. Figures referenced from MRI imaging (see Figures 1–2) will help illustrate the discussion. Finally, we will test your knowledge with quiz questions.

Etiology and Cause of Appendicitis in Pregnancy

Appendicitis is caused by obstruction of the appendiceal lumen, most often due to:

  • Fecaliths (appendicoliths) – calcified deposits that block the lumen.

  • Lymphoid hyperplasia – commonly associated with viral or bacterial infections.

  • Foreign bodies or parasites – rare, but possible triggers.

  • Neoplasms – uncommon, but can also cause obstruction.

In pregnancy, the etiology does not differ significantly. However, hormonal changes, increased intra-abdominal pressure, and displacement of abdominal organs by the gravid uterus can modify the clinical presentation and complicate diagnosis.

Pathophysiology

The sequence of pathophysiological events in appendicitis remains consistent:

  1. Obstruction → Increased intraluminal pressure.

  2. Vascular compromise → Mucosal ischemia, bacterial overgrowth.

  3. Inflammation → Appendiceal wall necrosis.

  4. Perforation → Localized or generalized peritonitis.

  5. Abscess formation → Particularly dangerous during pregnancy.

In pregnant patients, delayed diagnosis leads to higher perforation rates and worsens both maternal and fetal outcomes.

Epidemiology

  • Incidence: Occurs in 1 in 500 to 1 in 1,500 pregnancies.

  • Trimester distribution: Over 50% of cases occur during the second trimester.

  • Surgical relevance: Appendectomy is the most common non-obstetric surgery during pregnancy.

  • Complications: Perforation increases the risk of fetal loss threefold.

Clinical Presentation

The clinical picture in pregnant women is often atypical because of anatomical and physiological changes.

  • Classic symptoms:

    • Periumbilical pain shifting to the right lower quadrant.

    • Nausea and vomiting.

    • Fever and leukocytosis.

  • Pregnancy-related challenges:

    • Organ displacement by the enlarging uterus.

    • Leukocytosis is common in normal pregnancy, making laboratory interpretation difficult.

    • Nausea and vomiting may mimic hyperemesis gravidarum.

    • Physical exam limitations due to a gravid uterus.

This can lead to delayed diagnosis, often until perforation occurs.

Imaging Features

Ultrasound (US)

  • First-line imaging modality.

  • Strengths: Non-ionizing, safe for the fetus.

  • Limitations: Decreased accuracy in late pregnancy due to uterine size, bowel gas, and displaced anatomy.

Magnetic Resonance Imaging (MRI)

MRI is now the gold standard for pregnant patients with suspected appendicitis when ultrasound is inconclusive.

  • Non-ionizing: Safe for both mother and fetus.

  • Sequences used:

    • T2-weighted single-shot fast spin echo (SSFSE).

    • T1-weighted fat-saturated gradient echo.

    • Diffusion-weighted imaging (DWI).

  • Imaging findings:

    • Enlarged appendix (>6 mm diameter).

    • Appendicolith (Figure 1).

    • Periappendiceal inflammation, fluid, or abscess (Figure 2).

Figure 1. MRI T1-weighted image showing a 7 mm appendicolith at the base of the appendix.

Figure 2. Diffusion-weighted imaging (DWI) and apparent diffusion coefficient (ADC) map showing periappendiceal inflammatory changes with abscess formation.

Computed Tomography (CT)

  • Highly accurate, but generally avoided in pregnancy due to ionizing radiation.

Treatment

Surgical Management

  • Appendectomy is the treatment of choice.

  • Both laparoscopic and open approaches are used, though laparoscopic appendectomy is increasingly favored when performed by experienced surgeons.

Antibiotics

  • Broad-spectrum prophylactic antibiotics are recommended.

  • Used both preoperatively and postoperatively in complicated appendicitis.

Perforated Appendicitis

  • Requires urgent surgery.

  • Associated with higher risks of fetal loss, maternal sepsis, and preterm labor.

Prognosis

  • Uncomplicated appendicitis: Excellent prognosis with timely surgery.

  • Complicated appendicitis (perforation/abscess):

    • Maternal morbidity increases.

    • Fetal mortality risk rises threefold.

  • Recurrence: Rare after appendectomy.

The prognosis is therefore highly dependent on early recognition and prompt treatment.

Discussion and Clinical Implications

Diagnosing appendicitis in pregnancy is challenging due to overlapping symptoms with normal gestation and limitations in physical examination. MRI has revolutionized imaging in this population, providing safe, accurate diagnosis without ionizing radiation.

From a clinical perspective, a high index of suspicion is essential when pregnant women present with persistent or localized abdominal pain. Delayed treatment dramatically worsens outcomes, emphasizing the importance of early imaging and surgical referral.

Quiz Section


1. On T1-weighted MRI, why does a 7 mm appendicolith appear dark?

A) Lack of contrast enhancement

B) Even-numbered nuclei without intrinsic MR signal

C) Larmor frequency resonance

D) Signal modulation from J-coupling

2. Which imaging modality is considered first-line for suspected appendicitis in pregnancy?

A) CT

B) MRI

C) Ultrasound

D) PET-CT

3. What is the most common complication of delayed appendicitis diagnosis in pregnancy?

A) Bowel obstruction

B) Ovarian torsion

C) Perforation with periappendiceal abscess

D) Pulmonary embolism


Answer & Explanation

1. Answer: B) Even-numbered nuclei without intrinsic MR signal. Explanation: Calcium lacks nuclear spin and intrinsic MR signal, appearing dark on T1 imaging.

2. Answer: C) Ultrasound. Explanation: Ultrasound is first-line due to safety and accessibility, but MRI is recommended when US is inconclusive.

3. Answer: C) Perforation with periappendiceal abscess. Explanation: Delayed diagnosis frequently leads to perforation, with abscess formation that increases fetal mortality risk threefold.

References

[1] L. B. Spalluto, C. A. Woodfield, C. M. DeBenedectis, and E. Lazarus, "MR imaging evaluation of abdominal pain during pregnancy: appendicitis and other nonobstetric causes," Radiographics, vol. 32, no. 2, pp. 317-334, 2012, doi:10.1148/rg.322115057.

[2] J. Huang, "Nonobstetric surgery during pregnancy," Anesthesiology, pp. 395-403, 2017, doi:10.1007/978-3-319-50141-3_51.

[3] A. Oto, "MR imaging evaluation of acute abdominal pain during pregnancy," Magn Reson Imaging Clin N Am, vol. 14, no. 4, pp. 489-501, 2006, doi:10.1016/j.mric.2007.01.003.

[4] M. P. Federle, R. B. Jeffrey, P. J. Woodward, and A. Borhani, Diagnostic Imaging: Abdomen, 2nd ed., Philadelphia, PA: Lippincott Williams & Wilkins, 2009, pp. 135-139.

[5] S. Augustin, M. Jamison, and R. Singla, "Appendicitis in pregnancy: diagnosis, management and complications," Obstet Gynecol Surv, vol. 74, no. 12, pp. 793-801, 2019.

[6] M. Mazze and S. Källén, "Appendectomy during pregnancy: a Swedish registry study of 778 cases," Obstet Gynecol, vol. 89, no. 1, pp. 134-139, 1997.

Comments

Post a Comment