The diagnostic accuracy of ultrasound in the diagnosis of acute appendicitis in pregnancy

Objective: Clinically suspected appendicitis is the most common nonobstetric surgical problem encountered in pregnancy. The diagnosis of appendicitis is hampered by equivocal symptoms during pregnancy. Ultrasonography (US) remains, as a rule, the imaging test of choice for the diagnosis of clinically suspected appendicitis during pregnancy and other imaging tools such as computed tomography (CT) or magnetic resonance imaging (MRI) are usually avoided. We evaluated the accuracy of US in the diagnosis of appendicitis during pregnancy. Methods: The clinical and sonographic findings of all pregnant women (n = 90), who underwent appendectomy between January 2005 and December 2017 at our institution, were retrospectively reviewed, analyzed, and compared to the clinical and sonographic findings similarly obtained for a control group of nonpregnant women matched for age and date of surgery (+/- 6 months). The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of ultrasonic findings were calculated and compared between groups as well as within the three pregnancy trimesters. Results: The mean age of the patients was 31.3 +/- 0.4. Right lower quadrant pain was present in almost all patients (99%). The sole imaging modality used in our study cohort was US. Among nonpregnant controls, CT scan was primarily used on more occasions (53.3%) compared to US (45.6%). Nonpregnant women underwent significantly more laparoscopies compared to pregnant women (83.3 versus 45.6%, p < .001). The rate of negative appendectomy was higher in pregnant women (31.1 versus 10%, p = .002). Among pregnant women operated there was a higher rate of inconclusive or negative imaging (43.3 versus 11.1%, p < .001). The rate of perforated appendix at surgery was similar in both groups (6.7 and 4.4%, respectively, p = .75). Conclusions: Ultrasonography (US) is of mediocre accuracy for the diagnosis of acute appendicitis in pregnant patients beyond the first trimester of pregnancy. Thirty percent of pregnant women with suspected appendicitis are futilely operated. Given the low yield of US, a second-line imaging should be considered in cases of inconclusive US before surgery.