The diagnosis of acute appendicitis in the pregnant patient can be particularly challenging, as nausea, anorexia, and abdominal pain may be symptoms of both appendicitis and normal pregnancy. In addition, the gravid uterus can displace the abdominal viscera, shifting the location of the appendix from the right lower quadrant. Appendicitis affects 1 in every 1,400 pregnancies, an incidence similar to that of the nonpregnant female population.It can occur in any trimester, with perhaps a slight increase in frequency during the second trimester. Perforation is more common in the third trimester, however, and results from a longer duration from the onset of symptoms to operation. The differential diagnosis of appendicitis includes not only the conditions possible in nonpregnant women, but also certain conditions specific to pregnancy: ectopic pregnancy, chorioamnionitis, preterm labor, placental abruption, and round ligament pain.
In the first and early second trimesters, the presentation of appendicitis is similar to that seen in nonpregnant women. In the third trimester, women may not present with right lower quadrant pain due to displacement of the appendix by the gravid uterus. Baer and associates performed barium enemas on normal pregnant women and found the appendix to migrate superiorly towards the right upper quadrant in later stages of pregnancy. His findings suggest that appendicitis should present with right upper quadrant or flank pain in late pregnancy. Two retrospective studies contradict this, however, showing that even in the third trimester, pain and tenderness are more common in the right lower than the right upper quadrant. Nonetheless, right upper quadrant pain did predominate in some third-trimester patients with appendicitis in each study, reminding the clinician that right upper quadrant and right flank symptoms could be due to appendicitis in an appendix displaced by the gravid uterus.
Ultrasound is accurate in pregnancy and is a useful first radiological study because it has no known adverse fetal effects. Rectal contrast CT has also been shown to be highly accurate in the pregnant population. Although ionizing radiation has risks to the fetus, the radiation from a typical abdominopelvic CT is below the threshold of 5 rads at which teratogenic effects are seen.When the diagnosis is in doubt, the risk of radiation should be weighed against the risk of spontaneous abortion from an unnecessary laparotomy or from undiagnosed appendicitis progressing to perforation. Hospital admission with close observation for progression of symptoms is a viable alternative if the risks of radiation from CT scan are deemed excessive.
The pregnant patient should proceed directly to appendectomy if appendicitis is suspected. A normal appendix is not an uncommon finding, as negative laparotomy has been reported in approximately one-third of cases due to the difficulty of diagnosis in this population.Negative laparotomy should not be considered an error in diagnosis, because the risk to the fetus varies directly with the severity of appendicitis. In one series, fetal loss occurred in only 1 (3%) of 30 negative laparotomies. Fetal mortality rises to 5% in cases of nonperforated appendicitis, and increases to 20% when the appendix perforates. These data warrant an aggressive approach to appendectomy. Early negative exploration is justified to minimize the likelihood of progression to perforation.
Although laparoscopic appendectomy has become increasingly popular, its appropriateness during pregnancy remains in question. The gravid uterus can make laparoscopic visualization difficult, particularly if the appendix is located in the pelvis. In addition, carbon dioxide insufflation of the abdomen results in fetal hypercarbia and decreased placental blood flow, the effects of which have not been completely studied. Although case series of successful laparoscopy during pregnancy have been presented, the overall safety of laparoscopic appendectomy in pregnancy is uncertain. Until further research is available, the open approach is advised.