Primary appendicitis in pregnancy is very rare; recurrent appendicitis is not so rare. When appendicitis goes on to suppuration and perforative peritonitis the condition is worse in pregnant women than in the non-pregnant. In pregnancy protective adhesions, walling off, are less likely to occur; the inflammation is more intense owing to increased vascularity; thrombosis and phlebitis are more frequent; drainage may be obstructed and the burrowing of pus widespread; tympany, too, causes dyspnoea earlier. About 75 per cent. of the cases occur after the third month, and the earlier the appendicitis appears, the better the prognosis. During labor the contracting uterus sometimes tears open an adhesive appendix, or ruptures a pus sac and starts a general peritonitis. This condition may be mistaken for a general sepsis which is puerperal. Acute appendicitis is likely to be confused with an inflammation of a Fallopian tube. When the appendicitis is perforative abortion, infection of the uterine contents and death of the child happen in most cases. Labor is very painful when appendicitis is present, and the uterine contractions are often weak. After delivery many forms of infection of the uterus and its adnexa are possible.

Operation is much less difficult in the first half of gestation than in the latter months. At the beginning of gestation the operation does not, as a rule, cause abortion. Late in pregnancy appendicitis rapidly goes on to suppuration and perforation, with a high mortality. Hirst says that where there is reason to suspect suppuration a median incision should be made and the pelvic cavity examined for possible areas of infection. John Deaver says, "Always cut down on the sore spot and do not handle the uterus." An infected uterus after cesarean section complicated with appendicitis has to be amputated.

The diagnosis between appendicitis, ectopic gestation, twisted ovarian tumors, ureteritis, and ureteral stone is to be made. In a discussion of a paper by Finley on Appendicitis in Pregnancy,[117] Dr. John Murphy of Chicago, a great authority, advised operation as soon as the diagnosis is made, and he was of the opinion that this diagnosis is not difficult to make in pregnancy. Deaver said a diagnosis of catarrhal appendicitis is not seldom very difficult to make. This form is very rare in pregnancy. Deaver is not of the same opinion as Murphy as to operating as soon as the diagnosis is made in all cases. Where there is a general peritonitis, operation commonly only makes matters worse by spreading infection. The mortality of cases of appendicitis in pregnancy left without operation is as high as 77 per cent.; where the cases are operated upon within forty-eight hours after diagnosis the mortality is 6.7 per cent. and it would be better if the operation were done within twenty-four hours. Finley says that in the fifteen cases reviewed in his paper the operation did not cause abortion. Deaver tells us the muscular rigidity in the right groin characteristic of appendicitis is often missing in pregnancy, and that sometimes the pain is on the left side of the belly.