Suspected appendicitis is one of the most common indications for surgical abdominal exploration during pregnancy. A study involving more than 700,000 women reported that approximately 1 in 1000 women underwent appendectomy during pregnancy, with appendicitis confirmed in 65 percent (1 in 1500 pregnancies). Appendicitis may be less common during pregnancy than in nonpregnant women of similar age. This “protection” may be most apparent in third trimester.
Pregnancy often makes the diagnosis of appendicitis more difficult because (1) anorexia, nausea, and vomiting that accompany normal pregnancy are also common symptoms of appendicitis; (2) as the uterus enlarges, the appendix commonly moves upward and outward toward the flank, so that pain and tenderness may not be prominent in the right lower quadrant (see Figure 60-1); (3) some degree of leukocytosis is the rule during normal pregnancy; (4) appendicitis may be confused with preterm labor, pyelonephritis, renal colic, placental abruption, or degeneration of a uterine myoma; and (5) pregnant women, especially those late in gestation, frequently do not have symptoms considered “typical” for nonpregnant patients with appendicitis. As the appendix is pushed progressively higher by the growing uterus, containment of infection by the omentum becomes increasingly unlikely, and appendiceal rupture and generalized peritonitis are more common during later pregnancy.
FIGURE 60-1 Changes in position of the appendix as pregnancy advances. MO, month; PP, postpartum. (Modified from Baer JL, Reis RA, Arens RA: Appendicitis in pregnancy with changes in position and axis of normal appendix in pregnancy. JAMA 98:1359, 1932.)
Persistent abdominal pain and tenderness are the most reproducible findings. Most investigators have reported that pain migrates upward with appendiceal displacement with progressing pregnancy. Graded compression ultrasonography during pregnancy is difficult, because cecal displacement with uterine imposition makes precise examination difficult. Appendiceal computed tomography is more sensitive and accurate than ultrasound in nonpregnant patients. Observations in pregnant women are promising.
If appendicitis is suspected, treatment is immediate surgical exploration. Even though diagnostic errors sometimes lead to removal of a normal appendix, it is better to operate unnecessarily than to postpone intervention until generalized peritonitis has developed.
During the first half of pregnancy, laparoscopy for suspected appendicitis has become the norm. Although some clinicians have questioned the possibility of a CO2 pneumoperitoneum causing fetal acidosis and hypoperfusion, physiological responses as well as experience with its use is reassuring. In one large study it was found that perinatal outcomes in women undergoing laparoscopic procedures before 20 weeks’ gestation were no different than for those managed by laparotomy (see Chapter 88). If laparotomy is chosen, most practitioners prefer an incision over the McBurney point.
Prior to exploration, intravenous antimicrobials such as second-generation cephalosporins or penicillin/β-lactamase inhibitor combinations are given. Unless there is gangrene, perforation, or a periappendiceal phlegmon, antimicrobial therapy can be discontinued after surgery. If generalized peritonitis does not develop, then the prognosis is good. Seldom is cesarean delivery indicated at the time of appendectomy. Uterine contractions are common with peritonitis and, although some authors recommend tocolytic agents, we do not. It has been reported that increased intravenous fluid administration and tocolytic use increased the risk for pulmonary injury with antepartum appendicitis.
Undiagnosed appendicitis often stimulates labor. The large uterus frequently helps contain infection locally, but after delivery when the uterus rapidly empties, the walledoff infection is disrupted with spillage of free pus into the peritoneal cavity. In these cases, an acute surgical abdomen is encountered within a few hours postpartum. It is important to remember that puerperal pelvic infections typically do not cause peritonitis.
EFFECTS ON PREGNANCY
Appendicitis increases the likelihood of abortion or preterm labor, especially if there is peritonitis. Spontaneous labor ensues with greater frequency if surgery for appendicitis is performed after 23 weeks with fetal loss rates averaging approximately 20 percent. Increased fetal and maternal morbidity and mortality is almost invariably due to surgical delay. Authors have suggested a link between maternal-fetal sepsis and neonatal neurological injury in pregnancies complicated by appendicitis.
For further reading in Williams Obstetrics, 23rd ed.,
see Chapter 49, “Gastrointestinal Disorders.”