The differential diagnosis includes the following:

Diagnosis is based on a detailed history and the following symptoms:

The signs are the following:

Between 0.75% and 2% of pregnant women will require emergency nonobstetric surgery for acute appendicitis, cholecystitis, maternal trauma, and cancer. Appendicitis is the most common surgical emergency during pregnancy. The incidence varies from 1:350 to 1:10,000. Appendicitis is the reason for approximately 25% of operative indications for nonobstetric surgery during pregnancy. In epidemiologic studies, the reduced incidence of appendicitis in pregnant women compared to matched controls suggests a protective effect of pregnancy, especially in the third trimester.

It has been suggested that the incidence of gangrenous appendix has been reported to be higher during pregnancy because the enlarging uterus pushes the appendix away from the abdominal wall (Fig. 30.1), thereby causing the diseased appendix to produce little pain. This will delay the diagnosis and allow time for the appendix to become gangrenous. Recent studies using magnetic resonance imaging (MRI) have confirmed that the appendix is displaced upward to a mean distance of 45 mm above the iliac crest at term. This will frequently result in flank pain instead of the typical right lower quadrant pain as the presenting symptom in some women. Another factor contributing to the delay in diagnosis of a nonobstetric abdominal crisis is that useful diagnostic procedures such as radiography and laparoscopy are postponed because of concern for the fetus. Recent epidemiologic data, however, show no higher incidence of perforated appendix in pregnant women compared to matched controls.

Alder’s sign is a clinical sign used to differentiate between uterine and appendiceal pain.

The pain is localized with the patient supine. The patient then lies on her left side. If the area of pain shifts to the left, it is presumed to be uterine. According to one study, the Alder’s sign was positive in 36% of cases.

The incidence of perforation of the appendix is approximately 15%. Thirty percent of these occur in the first and second trimesters and 70% during the third trimester. The perforation rates for first, second, and third trimesters tend to be 8.7%, 12.1%, and 26.1%, respectively.

The incidence of surgery is estimated at between 0.75% and 2.2%. Most common causes are acute appendicitis, acute cholecystitis, maternal trauma, and cancer.

The main concerns are maternal and fetal safety. To ensure maternal safety, awareness of the physiologic changes of the parturient is of great importance. Special care should be taken to prevent aspiration pneumonitis especially after midgestation. Failed intubation is as much a risk during early pregnancy with nonobstetric surgery as it is during cesarean delivery. Faster uptake of anesthetics and a decrease in minimum alveolar concentration (MAC) for volatile anesthetics may render patients unconscious rapidly and at lower doses.

At as early as 8 weeks of gestation, most of the increase in cardiac output, increase in stroke volume, and decrease in vascular resistance are apparent and continue to midterm. At 32 weeks, this patient is also at risk of supine hypotensive syndrome. For fetal safety, it is essential to avoid teratogenic anesthetic agents and intrauterine fetal asphyxia. Maintenance of adequate maternal oxygenation, oxygen-carrying capacity, and uteroplacental perfusion are critical to fetal well-being.

The factors influencing teratogenicity are genetic factors, nature, and dose of the anesthetic agent used, access of the agent to the fetus, and fetal developmental stage.

In this case, teratogenicity is unlikely because the most susceptible time in the human is that of organogenesis between the 15th and the 30th day after conception; susceptibility declines thereafter to the 50th day. Almost all anesthetics are teratogenic in some animals. Before implantation of the ovum, teratogenicity leads to abortion. Later, malformation, functional deficiencies, and even death can occur. However, no documented reports are found of teratogenicity or increase in birth defects in humans ascribed to any anesthetic agent used during pregnancy. Evidence does not support any increase in congenital birth defects in pregnant patients receiving anesthesia irrespective of the type of anesthetics.

In 2007, the Anesthetic and Life Support Drugs Advisory Committee of the FDA concluded after reviewing the data that “there are not adequate data to extrapolate the animal findings to humans.” Swedish registries have validated the findings that anesthetics do not result in increased birth defects. In a consensus statement in the New England Journal of Medicine in 2000, no anesthetic agents were listed as definitively causative of fetal malformations. Nevertheless, most anesthesiologists adhere to the use of only time-tested anesthetics, rather than new agents in the pregnant patient, especially in the first trimester of pregnancy.