Acute appendicitis during pregnancy is the most common surgical abdominal emergency encountered in pregnancy, with an incidence of approximately 1 in 1,500 to 1 in 800 pregnancies. It can occur at any stage of pregnancy but is more commonly observed during the first six months of gestation. The enlarged uterus during pregnancy can alter the position of the appendix, leading to atypical clinical presentations and increased diagnostic difficulty. The risk of appendiceal perforation and peritonitis rises significantly during pregnancy, posing serious risks to both the mother and fetus. Early diagnosis and timely management have a significant impact on prognosis.
Positional Characteristics of the Appendix During Pregnancy
In early pregnancy, the location of the appendix is similar to that in non-pregnant individuals, situated at the junction of the middle and outer thirds of the line between the right anterior superior iliac spine and the umbilicus (McBurney’s point). As the uterus enlarges, the appendix gradually shifts upward and outward, moving posteriorly. It returns to its pre-pregnancy position approximately 14 days postpartum.
Effects on the Mother and Fetus
Effects on the Mother
The likelihood of diffuse peritonitis secondary to perforated appendicitis during pregnancy is 1.5–3.5 times higher than in non-pregnant individuals. This increased risk is attributed to several factors:
- Rich blood and lymphatic circulation in the pelvis, along with increased capillary permeability, accelerates the progression of inflammation and raises the risk of appendiceal perforation.
- The enlarged uterus separates the inflamed appendix from the parietal peritoneum, leading to atypical symptoms.
- The enlarged uterus displaces the greater omentum and limits its capability to contain and localize the inflammatory process.
- The proximity of the appendix to the uterus allows the inflammation to involve the uterus, triggering uterine contractions that further promote the spread of inflammation, increasing the risk of diffuse peritonitis.
- The altered position of the appendix and the masking effect of an enlarged uterus obscure abdominal muscular guarding and peritoneal irritation signs, resulting in clinical findings that underestimate the extent of pathological changes, increasing the likelihood of misdiagnosis and delayed treatment.
Effects on the Fetus
Systemic inflammatory responses and diffuse peritonitis may lead to fetal hypoxia. Additionally, uterine contractions stimulated by the inflammatory process may result in miscarriage or preterm labor. Surgical and pharmacological interventions during pregnancy may also negatively impact the fetus, thereby increasing perinatal mortality rates.
Clinical Presentation and Diagnosis
Pregnancy does not increase the incidence of acute appendicitis. However, the symptoms and signs of acute appendicitis during pregnancy are influenced by the physiological changes associated with pregnancy, complicating diagnosis and treatment. Delayed diagnosis and management clearly elevate the risk of adverse maternal and fetal outcomes. Greater awareness of the positional changes of the appendix during mid and late pregnancy, along with thorough history-taking and physical examinations, facilitates earlier diagnosis.
The clinical presentation of acute appendicitis during pregnancy varies depending on the stage of pregnancy.
- Early Pregnancy: Symptoms and signs are generally similar to those in non-pregnant individuals. Abdominal pain remains the most common symptom, and approximately 80% of patients present with migratory pain to the right lower quadrant, along with tenderness, rebound tenderness, and abdominal muscle guarding in this region.
- Mid and Late Pregnancy: The enlarged uterus alters the anatomical position of the appendix, often resulting in atypical presentations. Migratory pain is less common, and the location of abdominal pain and tenderness is higher. If the appendix is located posterior to the uterus, the pain may manifest in the right flank. During this period, the distended uterus elevates the parietal peritoneum, making tenderness, rebound tenderness, and abdominal muscle guarding less apparent.
Severe cases may present with toxicity symptoms such as fever and tachycardia, as well as gastrointestinal symptoms such as nausea, vomiting, and anorexia. Since physiological leukocytosis occurs during pregnancy, leukocyte counts exceeding 15 × 10⁹/L and neutrophilia have diagnostic significance. Ultrasound and magnetic resonance imaging (MRI) can assist in confirming the diagnosis.
Differential Diagnosis
In early pregnancy, the diagnosis of acute appendicitis is typically straightforward when symptoms are classic. However, differentiation from torsion of a right-sided ovarian cyst and rupture of a right-sided tubal pregnancy is necessary.
In mid-pregnancy, conditions that require differentiation include torsion of the right ovarian cyst, red degeneration of a uterine fibroid, right-sided hydronephrosis, acute pyelonephritis, right ureteral stones, and acute cholecystitis.
In late pregnancy, differential diagnoses include preterm labor, placental abruption, acute fatty liver of pregnancy, intestinal adhesions, intestinal obstruction, and intestinal perforation.
During the puerperium, distinguishing acute appendicitis from puerperal infection may be particularly challenging.
Management
The probability of appendiceal perforation in pregnancy is 1.5 to 3.5 times higher compared to non-pregnant individuals. When inflammation involves the uterine serosa, it can stimulate uterine contractions, facilitating the spread of appendiceal inflammation and consequently leading to miscarriage, preterm birth, or even fetal demise. The fetal prognosis is directly related to whether appendiceal perforation occurs. In cases of simple appendicitis without perforation, fetal mortality ranges from 1.5% to 4%. However, fetal mortality significantly increases to 21%–35% in cases complicated by appendiceal perforation leading to diffuse peritonitis. Conservative treatment for acute appendicitis during pregnancy is generally not advocated. Once the diagnosis is established, immediate appendectomy should be performed alongside aggressive antibiotic therapy. In cases of strong suspicion of acute appendicitis during mid or late pregnancy where diagnosis remains challenging, exploratory laparotomy should be strongly considered.
Surgical Treatment
Both open surgery and laparoscopic surgery can be considered as surgical approaches. However, the safety of laparoscopic surgery during pregnancy remains controversial. Some reports have suggested an increased risk of preterm birth following laparoscopic appendectomy during pregnancy. For open surgery, spinal anesthesia is preferred. Precautions during surgery should include prevention of supine hypotensive syndrome in pregnant individuals. In early pregnancy, a McBurney incision can be used. When the diagnosis is uncertain, a lower midline vertical incision can offer better operative exposure and facilitate exploration. During mid or late pregnancy, the surgical incision should be made at the area of greatest tenderness. A left tilt of approximately 30° should be applied to the operating table to displace the uterus to the left, aiding exposure of the appendix. Atraumatic surgical techniques should be employed to minimize uterine stimulation. For late-stage pregnancy cases requiring concurrent cesarean delivery, a lower midline vertical incision suitable for cesarean section is recommended. If severe localized inflammation, appendiceal perforation, or cecal wall edema is observed, intra-abdominal drainage may be necessary.
Unless obstetric emergencies dictate otherwise, the general principle is to address appendicitis without performing a simultaneous cesarean delivery. However, cesarean delivery followed by appendectomy may be performed under the following circumstances:
- Difficulty in exposing the appendix during surgery.
- Appendiceal perforation with diffuse peritonitis, severe pelvic infection, and signs of uterine infection.
- Near-term pregnancy or fetal maturity, where the fetus is viable.
Postoperative Management
For individuals requiring continuation of pregnancy post-surgery, broad-spectrum antibiotics should be selected based on sensitivity to pathogens and minimal risk to the fetus. Anaerobic infection accounts for 75%–90% of cases, and antimicrobial therapy targeting anaerobic bacteria is recommended. A combination of metronidazole with penicillins or cephalosporins is suggested. Postoperative use of uterine contraction inhibitors, when appropriate, may reduce the risk of miscarriage or preterm birth.
In cases where the fetus has reached maturity and indications for cesarean delivery exist, cesarean delivery can be performed concurrently. Post-surgery, aggressive infection control measures should be implemented.